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<h1 class="title">JS App Walkthrough</h1>
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    How to build a website with custom JavaScript in FastHTML step-by-step
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<!-- WARNING: THIS FILE WAS AUTOGENERATED! DO NOT EDIT! -->
<section id="installation" class="level2">
<h2 class="anchored" data-anchor-id="installation">Installation</h2>
<p>You’ll need the following software to complete the tutorial, read on for specific installation instructions:</p>
<ol type="1">
<li>Python</li>
<li>A Python package manager such as pip (which normally comes with Python) or uv</li>
<li>FastHTML</li>
<li>Web browser</li>
<li>Railway.app account</li>
</ol>
<p>If you haven’t worked with Python before, we recommend getting started with <a href="https://docs.anaconda.com/miniconda/">Miniconda</a>.</p>
<p>Note that you will only need to follow the steps in the installation section once per environment. If you create a new repo, you won’t need to redo these.</p>
<section id="install-fasthtml" class="level3">
<h3 class="anchored" data-anchor-id="install-fasthtml">Install FastHTML</h3>
<p>For Mac, Windows and Linux, enter:</p>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh code-with-copy"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">pip</span> install python-fasthtml</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
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<section id="first-steps" class="level2">
<h2 class="anchored" data-anchor-id="first-steps">First steps</h2>
<p>By the end of this section you’ll have your own FastHTML website with tests deployed to railway.app.</p>
<section id="create-a-hello-world" class="level3">
<h3 class="anchored" data-anchor-id="create-a-hello-world">Create a hello world</h3>
<p>Create a new folder to organize all the files for your project. Inside this folder, create a file called <code>main.py</code> and add the following code to it:</p>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
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<div class="sourceCode" id="cb2" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> fasthtml.common <span class="im">import</span> <span class="op">*</span></span>
<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a>app <span class="op">=</span> FastHTML()</span>
<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>rt <span class="op">=</span> app.route</span>
<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">'/'</span>)</span>
<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get():</span>
<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="st">'Hello, world!'</span></span>
<span id="cb2-9"><a href="#cb2-9" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb2-10"><a href="#cb2-10" aria-hidden="true" tabindex="-1"></a>serve()</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<p>Finally, run <code>python main.py</code> in your terminal and open your browser to the ‘Link’ that appears.</p>
</section>
<section id="quickdraw-a-fasthtml-adventure" class="level3">
<h3 class="anchored" data-anchor-id="quickdraw-a-fasthtml-adventure">QuickDraw: A FastHTML Adventure 🎨✨</h3>
<p>The end result of this tutorial will be QuickDraw, a real-time collaborative drawing app using FastHTML. Here is what the final site will look like:</p>
<div class="quarto-figure quarto-figure-center">
<figure class="figure">
<p><img src="imgs/quickdraw.png" class="img-fluid figure-img"></p>
<figcaption>QuickDraw</figcaption>
</figure>
</div>
<section id="drawing-rooms" class="level4">
<h4 class="anchored" data-anchor-id="drawing-rooms">Drawing Rooms</h4>
<p>Drawing rooms are the core concept of our application. Each room represents a separate drawing space where a user can let their inner Picasso shine. Here’s a detailed breakdown:</p>
<ol type="1">
<li>Room Creation and Storage</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb3" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>db <span class="op">=</span> database(<span class="st">'data/drawapp.db'</span>)</span>
<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>rooms <span class="op">=</span> db.t.rooms</span>
<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> rooms <span class="kw">not</span> <span class="kw">in</span> db.t:</span>
<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>    rooms.create(<span class="bu">id</span><span class="op">=</span><span class="bu">int</span>, name<span class="op">=</span><span class="bu">str</span>, created_at<span class="op">=</span><span class="bu">str</span>, pk<span class="op">=</span><span class="st">'id'</span>)</span>
<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a>Room <span class="op">=</span> rooms.dataclass()</span>
<span id="cb3-6"><a href="#cb3-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb3-7"><a href="#cb3-7" aria-hidden="true" tabindex="-1"></a><span class="at">@patch</span></span>
<span id="cb3-8"><a href="#cb3-8" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> __ft__(<span class="va">self</span>:Room):</span>
<span id="cb3-9"><a href="#cb3-9" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Li(A(<span class="va">self</span>.name, href<span class="op">=</span><span class="ss">f"/rooms/</span><span class="sc">{</span><span class="va">self</span><span class="sc">.</span><span class="bu">id</span><span class="sc">}</span><span class="ss">"</span>))</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<p>Or you can use our <code>fast_app</code> function to create a FastHTML app with a SQLite database and dataclass in one line:</p>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb4" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> render(room):</span>
<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Li(A(room.name, href<span class="op">=</span><span class="ss">f"/rooms/</span><span class="sc">{</span>room<span class="sc">.</span><span class="bu">id</span><span class="sc">}</span><span class="ss">"</span>))</span>
<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a>app,rt,rooms,Room <span class="op">=</span> fast_app(<span class="st">'data/drawapp.db'</span>, render<span class="op">=</span>render, <span class="bu">id</span><span class="op">=</span><span class="bu">int</span>, name<span class="op">=</span><span class="bu">str</span>, created_at<span class="op">=</span><span class="bu">str</span>, pk<span class="op">=</span><span class="st">'id'</span>)</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<p>We are specifying a render function to convert our dataclass into HTML, which is the same as extending the <code>__ft__</code> method from the <code>patch</code> decorator we used before. We will use this method for the rest of the tutorial since it is a lot cleaner and easier to read.</p>
<ul>
<li>We’re using a SQLite database (via FastLite) to store our rooms.</li>
<li>Each room has an id (integer), a name (string), and a created_at timestamp (string).</li>
<li>The Room dataclass is automatically generated based on this structure.</li>
</ul>
<ol start="2" type="1">
<li>Creating a room</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb5" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/"</span>)</span>
<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get():</span>
<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># The 'Input' id defaults to the same as the name, so you can omit it if you wish</span></span>
<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>    create_room <span class="op">=</span> Form(Input(<span class="bu">id</span><span class="op">=</span><span class="st">"name"</span>, name<span class="op">=</span><span class="st">"name"</span>, placeholder<span class="op">=</span><span class="st">"New Room Name"</span>),</span>
<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>                       Button(<span class="st">"Create Room"</span>),</span>
<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>                       hx_post<span class="op">=</span><span class="st">"/rooms"</span>, hx_target<span class="op">=</span><span class="st">"#rooms-list"</span>, hx_swap<span class="op">=</span><span class="st">"afterbegin"</span>)</span>
<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>    rooms_list <span class="op">=</span> Ul(<span class="op">*</span>rooms(order_by<span class="op">=</span><span class="st">'id DESC'</span>), <span class="bu">id</span><span class="op">=</span><span class="st">'rooms-list'</span>)</span>
<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="st">"DrawCollab"</span>, </span>
<span id="cb5-9"><a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>                  H1(<span class="st">"DrawCollab"</span>),</span>
<span id="cb5-10"><a href="#cb5-10" aria-hidden="true" tabindex="-1"></a>                  create_room, rooms_list)</span>
<span id="cb5-11"><a href="#cb5-11" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb5-12"><a href="#cb5-12" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms"</span>)</span>
<span id="cb5-13"><a href="#cb5-13" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> post(room:Room):</span>
<span id="cb5-14"><a href="#cb5-14" aria-hidden="true" tabindex="-1"></a>    room.created_at <span class="op">=</span> datetime.now().isoformat()</span>
<span id="cb5-15"><a href="#cb5-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> rooms.insert(room)</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<ul>
<li>When a user submits the “Create Room” form, this route is called.</li>
<li>It creates a new Room object, sets the creation time, and inserts it into the database.</li>
<li>It returns an HTML list item with a link to the new room, which is dynamically added to the room list on the homepage thanks to HTMX.</li>
</ul>
<ol start="3" type="1">
<li>Let’s give our rooms shape</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb6" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">"</span>)</span>
<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="ss">f"Room: </span><span class="sc">{</span>room<span class="sc">.</span>name<span class="sc">}</span><span class="ss">"</span>, H1(<span class="ss">f"Welcome to </span><span class="sc">{</span>room<span class="sc">.</span>name<span class="sc">}</span><span class="ss">"</span>), A(Button(<span class="st">"Leave Room"</span>), href<span class="op">=</span><span class="st">"/"</span>))</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<ul>
<li>This route renders the interface for a specific room.</li>
<li>It fetches the room from the database and renders a title, heading, and paragraph.</li>
</ul>
<p>Here is the full code so far:</p>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb7" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> fasthtml.common <span class="im">import</span> <span class="op">*</span></span>
<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> datetime <span class="im">import</span> datetime</span>
<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> render(room):</span>
<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Li(A(room.name, href<span class="op">=</span><span class="ss">f"/rooms/</span><span class="sc">{</span>room<span class="sc">.</span><span class="bu">id</span><span class="sc">}</span><span class="ss">"</span>))</span>
<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a>app,rt,rooms,Room <span class="op">=</span> fast_app(<span class="st">'data/drawapp.db'</span>, render<span class="op">=</span>render, <span class="bu">id</span><span class="op">=</span><span class="bu">int</span>, name<span class="op">=</span><span class="bu">str</span>, created_at<span class="op">=</span><span class="bu">str</span>, pk<span class="op">=</span><span class="st">'id'</span>)</span>
<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-9"><a href="#cb7-9" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/"</span>)</span>
<span id="cb7-10"><a href="#cb7-10" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get():</span>
<span id="cb7-11"><a href="#cb7-11" aria-hidden="true" tabindex="-1"></a>    create_room <span class="op">=</span> Form(Input(<span class="bu">id</span><span class="op">=</span><span class="st">"name"</span>, name<span class="op">=</span><span class="st">"name"</span>, placeholder<span class="op">=</span><span class="st">"New Room Name"</span>),</span>
<span id="cb7-12"><a href="#cb7-12" aria-hidden="true" tabindex="-1"></a>                       Button(<span class="st">"Create Room"</span>),</span>
<span id="cb7-13"><a href="#cb7-13" aria-hidden="true" tabindex="-1"></a>                       hx_post<span class="op">=</span><span class="st">"/rooms"</span>, hx_target<span class="op">=</span><span class="st">"#rooms-list"</span>, hx_swap<span class="op">=</span><span class="st">"afterbegin"</span>)</span>
<span id="cb7-14"><a href="#cb7-14" aria-hidden="true" tabindex="-1"></a>    rooms_list <span class="op">=</span> Ul(<span class="op">*</span>rooms(order_by<span class="op">=</span><span class="st">'id DESC'</span>), <span class="bu">id</span><span class="op">=</span><span class="st">'rooms-list'</span>)</span>
<span id="cb7-15"><a href="#cb7-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="st">"DrawCollab"</span>, create_room, rooms_list)</span>
<span id="cb7-16"><a href="#cb7-16" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-17"><a href="#cb7-17" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms"</span>)</span>
<span id="cb7-18"><a href="#cb7-18" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> post(room:Room):</span>
<span id="cb7-19"><a href="#cb7-19" aria-hidden="true" tabindex="-1"></a>    room.created_at <span class="op">=</span> datetime.now().isoformat()</span>
<span id="cb7-20"><a href="#cb7-20" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> rooms.insert(room)</span>
<span id="cb7-21"><a href="#cb7-21" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-22"><a href="#cb7-22" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">"</span>)</span>
<span id="cb7-23"><a href="#cb7-23" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb7-24"><a href="#cb7-24" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb7-25"><a href="#cb7-25" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="ss">f"Room: </span><span class="sc">{</span>room<span class="sc">.</span>name<span class="sc">}</span><span class="ss">"</span>, H1(<span class="ss">f"Welcome to </span><span class="sc">{</span>room<span class="sc">.</span>name<span class="sc">}</span><span class="ss">"</span>), A(Button(<span class="st">"Leave Room"</span>), href<span class="op">=</span><span class="st">"/"</span>))</span>
<span id="cb7-26"><a href="#cb7-26" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-27"><a href="#cb7-27" aria-hidden="true" tabindex="-1"></a>serve()</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<p>Now run <code>python main.py</code> in your terminal and open your browser to the ‘Link’ that appears. You should see a page with a form to create a new room and a list of existing rooms.</p>
</section>
<section id="the-canvas---lets-get-drawing" class="level4">
<h4 class="anchored" data-anchor-id="the-canvas---lets-get-drawing">The Canvas - Let’s Get Drawing! 🖌️</h4>
<p>Time to add the actual drawing functionality. We’ll use Fabric.js for this:</p>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb8" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="co"># ... (keep the previous imports and database setup)</span></span>
<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">"</span>)</span>
<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>    canvas <span class="op">=</span> Canvas(<span class="bu">id</span><span class="op">=</span><span class="st">"canvas"</span>, width<span class="op">=</span><span class="st">"800"</span>, height<span class="op">=</span><span class="st">"600"</span>)</span>
<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>    color_picker <span class="op">=</span> Input(<span class="bu">type</span><span class="op">=</span><span class="st">"color"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"color-picker"</span>, value<span class="op">=</span><span class="st">"#3CDD8C"</span>)</span>
<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a>    brush_size <span class="op">=</span> Input(<span class="bu">type</span><span class="op">=</span><span class="st">"range"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"brush-size"</span>, <span class="bu">min</span><span class="op">=</span><span class="st">"1"</span>, <span class="bu">max</span><span class="op">=</span><span class="st">"50"</span>, value<span class="op">=</span><span class="st">"10"</span>)</span>
<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a>    </span>
<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>    js <span class="op">=</span> <span class="st">"""</span></span>
<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a><span class="st">    var canvas = new fabric.Canvas('canvas');</span></span>
<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a><span class="st">    canvas.isDrawingMode = true;</span></span>
<span id="cb8-13"><a href="#cb8-13" aria-hidden="true" tabindex="-1"></a><span class="st">    canvas.freeDrawingBrush.color = '#3CDD8C';</span></span>
<span id="cb8-14"><a href="#cb8-14" aria-hidden="true" tabindex="-1"></a><span class="st">    canvas.freeDrawingBrush.width = 10;</span></span>
<span id="cb8-15"><a href="#cb8-15" aria-hidden="true" tabindex="-1"></a><span class="st">    </span></span>
<span id="cb8-16"><a href="#cb8-16" aria-hidden="true" tabindex="-1"></a><span class="st">    document.getElementById('color-picker').onchange = function() {</span></span>
<span id="cb8-17"><a href="#cb8-17" aria-hidden="true" tabindex="-1"></a><span class="st">        canvas.freeDrawingBrush.color = this.value;</span></span>
<span id="cb8-18"><a href="#cb8-18" aria-hidden="true" tabindex="-1"></a><span class="st">    };</span></span>
<span id="cb8-19"><a href="#cb8-19" aria-hidden="true" tabindex="-1"></a><span class="st">    </span></span>
<span id="cb8-20"><a href="#cb8-20" aria-hidden="true" tabindex="-1"></a><span class="st">    document.getElementById('brush-size').oninput = function() {</span></span>
<span id="cb8-21"><a href="#cb8-21" aria-hidden="true" tabindex="-1"></a><span class="st">        canvas.freeDrawingBrush.width = parseInt(this.value, 10);</span></span>
<span id="cb8-22"><a href="#cb8-22" aria-hidden="true" tabindex="-1"></a><span class="st">    };</span></span>
<span id="cb8-23"><a href="#cb8-23" aria-hidden="true" tabindex="-1"></a><span class="st">    """</span></span>
<span id="cb8-24"><a href="#cb8-24" aria-hidden="true" tabindex="-1"></a>    </span>
<span id="cb8-25"><a href="#cb8-25" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="ss">f"Room: </span><span class="sc">{</span>room<span class="sc">.</span>name<span class="sc">}</span><span class="ss">"</span>,</span>
<span id="cb8-26"><a href="#cb8-26" aria-hidden="true" tabindex="-1"></a>                  A(Button(<span class="st">"Leave Room"</span>), href<span class="op">=</span><span class="st">"/"</span>),</span>
<span id="cb8-27"><a href="#cb8-27" aria-hidden="true" tabindex="-1"></a>                  canvas,</span>
<span id="cb8-28"><a href="#cb8-28" aria-hidden="true" tabindex="-1"></a>                  Div(color_picker, brush_size),</span>
<span id="cb8-29"><a href="#cb8-29" aria-hidden="true" tabindex="-1"></a>                  Script(src<span class="op">=</span><span class="st">"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/5.3.1/fabric.min.js"</span>),</span>
<span id="cb8-30"><a href="#cb8-30" aria-hidden="true" tabindex="-1"></a>                  Script(js))</span>
<span id="cb8-31"><a href="#cb8-31" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb8-32"><a href="#cb8-32" aria-hidden="true" tabindex="-1"></a><span class="co"># ... (keep the serve() part)</span></span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<p>Now we’ve got a drawing canvas! FastHTML makes it easy to include external libraries and add custom JavaScript.</p>
</section>
<section id="saving-and-loading-canvases" class="level4">
<h4 class="anchored" data-anchor-id="saving-and-loading-canvases">Saving and Loading Canvases 💾</h4>
<p>Now that we have a working drawing canvas, let’s add the ability to save and load drawings. We’ll modify our database schema to include a <code>canvas_data</code> field, and add new routes for saving and loading canvas data. Here’s how we’ll update our code:</p>
<ol type="1">
<li>Modify the database schema:</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb9" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>app,rt,rooms,Room <span class="op">=</span> fast_app(<span class="st">'data/drawapp.db'</span>, render<span class="op">=</span>render, <span class="bu">id</span><span class="op">=</span><span class="bu">int</span>, name<span class="op">=</span><span class="bu">str</span>, created_at<span class="op">=</span><span class="bu">str</span>, canvas_data<span class="op">=</span><span class="bu">str</span>, pk<span class="op">=</span><span class="st">'id'</span>)</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<ol start="2" type="1">
<li>Add a save button that grabs the canvas’ state and sends it to the server:</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb10" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">"</span>)</span>
<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a>    canvas <span class="op">=</span> Canvas(<span class="bu">id</span><span class="op">=</span><span class="st">"canvas"</span>, width<span class="op">=</span><span class="st">"800"</span>, height<span class="op">=</span><span class="st">"600"</span>)</span>
<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    color_picker <span class="op">=</span> Input(<span class="bu">type</span><span class="op">=</span><span class="st">"color"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"color-picker"</span>, value<span class="op">=</span><span class="st">"#3CDD8C"</span>)</span>
<span id="cb10-6"><a href="#cb10-6" aria-hidden="true" tabindex="-1"></a>    brush_size <span class="op">=</span> Input(<span class="bu">type</span><span class="op">=</span><span class="st">"range"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"brush-size"</span>, <span class="bu">min</span><span class="op">=</span><span class="st">"1"</span>, <span class="bu">max</span><span class="op">=</span><span class="st">"50"</span>, value<span class="op">=</span><span class="st">"10"</span>)</span>
<span id="cb10-7"><a href="#cb10-7" aria-hidden="true" tabindex="-1"></a>    save_button <span class="op">=</span> Button(<span class="st">"Save Canvas"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"save-canvas"</span>, hx_post<span class="op">=</span><span class="ss">f"/rooms/</span><span class="sc">{</span><span class="bu">id</span><span class="sc">}</span><span class="ss">/save"</span>, hx_vals<span class="op">=</span><span class="st">"js:{canvas_data: JSON.stringify(canvas.toJSON())}"</span>)</span>
<span id="cb10-8"><a href="#cb10-8" aria-hidden="true" tabindex="-1"></a>    <span class="co"># ... (rest of the function remains the same)</span></span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<ol start="3" type="1">
<li>Add routes for saving and loading canvas data:</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb11" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">/save"</span>)</span>
<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> post(<span class="bu">id</span>:<span class="bu">int</span>, canvas_data:<span class="bu">str</span>):</span>
<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a>    rooms.update({<span class="st">'canvas_data'</span>: canvas_data}, <span class="bu">id</span>)</span>
<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="st">"Canvas saved successfully"</span></span>
<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">/load"</span>)</span>
<span id="cb11-7"><a href="#cb11-7" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb11-8"><a href="#cb11-8" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb11-9"><a href="#cb11-9" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> room.canvas_data <span class="cf">if</span> room.canvas_data <span class="cf">else</span> <span class="st">"</span><span class="sc">{}</span><span class="st">"</span></span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<ol start="4" type="1">
<li>Update the JavaScript to load existing canvas data:</li>
</ol>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb12" data-filename="main.py"><pre class="sourceCode javascript code-with-copy"><code class="sourceCode javascript"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>js <span class="op">=</span> f<span class="st">"""</span></span>
<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a>    <span class="kw">var</span> canvas <span class="op">=</span> <span class="kw">new</span> fabric<span class="op">.</span><span class="fu">Canvas</span>(<span class="st">'canvas'</span>)<span class="op">;</span></span>
<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>    canvas<span class="op">.</span><span class="at">isDrawingMode</span> <span class="op">=</span> <span class="kw">true</span><span class="op">;</span></span>
<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a>    canvas<span class="op">.</span><span class="at">freeDrawingBrush</span><span class="op">.</span><span class="at">color</span> <span class="op">=</span> <span class="st">'#3CDD8C'</span><span class="op">;</span></span>
<span id="cb12-5"><a href="#cb12-5" aria-hidden="true" tabindex="-1"></a>    canvas<span class="op">.</span><span class="at">freeDrawingBrush</span><span class="op">.</span><span class="at">width</span> <span class="op">=</span> <span class="dv">10</span><span class="op">;</span></span>
<span id="cb12-6"><a href="#cb12-6" aria-hidden="true" tabindex="-1"></a>    <span class="co">// Load existing canvas data</span></span>
<span id="cb12-7"><a href="#cb12-7" aria-hidden="true" tabindex="-1"></a>    <span class="fu">fetch</span>(<span class="vs">`/rooms/{id}/load`</span>)</span>
<span id="cb12-8"><a href="#cb12-8" aria-hidden="true" tabindex="-1"></a>    <span class="op">.</span><span class="fu">then</span>(response <span class="kw">=&gt;</span> response<span class="op">.</span><span class="fu">json</span>())</span>
<span id="cb12-9"><a href="#cb12-9" aria-hidden="true" tabindex="-1"></a>    <span class="op">.</span><span class="fu">then</span>(data <span class="kw">=&gt;</span> {{</span>
<span id="cb12-10"><a href="#cb12-10" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> (data <span class="op">&amp;&amp;</span> <span class="bu">Object</span><span class="op">.</span><span class="fu">keys</span>(data)<span class="op">.</span><span class="at">length</span> <span class="op">&gt;</span> <span class="dv">0</span>) {{</span>
<span id="cb12-11"><a href="#cb12-11" aria-hidden="true" tabindex="-1"></a>            canvas<span class="op">.</span><span class="fu">loadFromJSON</span>(data<span class="op">,</span> canvas<span class="op">.</span><span class="at">renderAll</span><span class="op">.</span><span class="fu">bind</span>(canvas))<span class="op">;</span></span>
<span id="cb12-12"><a href="#cb12-12" aria-hidden="true" tabindex="-1"></a>        }}</span>
<span id="cb12-13"><a href="#cb12-13" aria-hidden="true" tabindex="-1"></a>    }})<span class="op">;</span></span>
<span id="cb12-14"><a href="#cb12-14" aria-hidden="true" tabindex="-1"></a>    </span>
<span id="cb12-15"><a href="#cb12-15" aria-hidden="true" tabindex="-1"></a>    <span class="co">// ... (rest of the JavaScript remains the same)</span></span>
<span id="cb12-16"><a href="#cb12-16" aria-hidden="true" tabindex="-1"></a><span class="st">"""</span></span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
<p>With these changes, users can now save their drawings and load them when they return to the room. The canvas data is stored as a JSON string in the database, allowing for easy serialization and deserialization. Try it out! Create a new room, make a drawing, save it, and then reload the page. You should see your drawing reappear, ready for further editing.</p>
<p>Here is the completed code:</p>
<div class="code-with-filename">
<div class="code-with-filename-file">
<pre><strong>main.py</strong></pre>
</div>
<div class="sourceCode" id="cb13" data-filename="main.py"><pre class="sourceCode python code-with-copy"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> fasthtml.common <span class="im">import</span> <span class="op">*</span></span>
<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> datetime <span class="im">import</span> datetime</span>
<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> render(room):</span>
<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Li(A(room.name, href<span class="op">=</span><span class="ss">f"/rooms/</span><span class="sc">{</span>room<span class="sc">.</span><span class="bu">id</span><span class="sc">}</span><span class="ss">"</span>))</span>
<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a>app,rt,rooms,Room <span class="op">=</span> fast_app(<span class="st">'data/drawapp.db'</span>, render<span class="op">=</span>render, <span class="bu">id</span><span class="op">=</span><span class="bu">int</span>, name<span class="op">=</span><span class="bu">str</span>, created_at<span class="op">=</span><span class="bu">str</span>, canvas_data<span class="op">=</span><span class="bu">str</span>, pk<span class="op">=</span><span class="st">'id'</span>)</span>
<span id="cb13-8"><a href="#cb13-8" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-9"><a href="#cb13-9" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/"</span>)</span>
<span id="cb13-10"><a href="#cb13-10" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get():</span>
<span id="cb13-11"><a href="#cb13-11" aria-hidden="true" tabindex="-1"></a>    create_room <span class="op">=</span> Form(Input(<span class="bu">id</span><span class="op">=</span><span class="st">"name"</span>, name<span class="op">=</span><span class="st">"name"</span>, placeholder<span class="op">=</span><span class="st">"New Room Name"</span>),</span>
<span id="cb13-12"><a href="#cb13-12" aria-hidden="true" tabindex="-1"></a>                       Button(<span class="st">"Create Room"</span>),</span>
<span id="cb13-13"><a href="#cb13-13" aria-hidden="true" tabindex="-1"></a>                       hx_post<span class="op">=</span><span class="st">"/rooms"</span>, hx_target<span class="op">=</span><span class="st">"#rooms-list"</span>, hx_swap<span class="op">=</span><span class="st">"afterbegin"</span>)</span>
<span id="cb13-14"><a href="#cb13-14" aria-hidden="true" tabindex="-1"></a>    rooms_list <span class="op">=</span> Ul(<span class="op">*</span>rooms(order_by<span class="op">=</span><span class="st">'id DESC'</span>), <span class="bu">id</span><span class="op">=</span><span class="st">'rooms-list'</span>)</span>
<span id="cb13-15"><a href="#cb13-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="st">"QuickDraw"</span>, </span>
<span id="cb13-16"><a href="#cb13-16" aria-hidden="true" tabindex="-1"></a>                  create_room, rooms_list)</span>
<span id="cb13-17"><a href="#cb13-17" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-18"><a href="#cb13-18" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms"</span>)</span>
<span id="cb13-19"><a href="#cb13-19" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> post(room:Room):</span>
<span id="cb13-20"><a href="#cb13-20" aria-hidden="true" tabindex="-1"></a>    room.created_at <span class="op">=</span> datetime.now().isoformat()</span>
<span id="cb13-21"><a href="#cb13-21" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> rooms.insert(room)</span>
<span id="cb13-22"><a href="#cb13-22" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-23"><a href="#cb13-23" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">"</span>)</span>
<span id="cb13-24"><a href="#cb13-24" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb13-25"><a href="#cb13-25" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb13-26"><a href="#cb13-26" aria-hidden="true" tabindex="-1"></a>    canvas <span class="op">=</span> Canvas(<span class="bu">id</span><span class="op">=</span><span class="st">"canvas"</span>, width<span class="op">=</span><span class="st">"800"</span>, height<span class="op">=</span><span class="st">"600"</span>)</span>
<span id="cb13-27"><a href="#cb13-27" aria-hidden="true" tabindex="-1"></a>    color_picker <span class="op">=</span> Input(<span class="bu">type</span><span class="op">=</span><span class="st">"color"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"color-picker"</span>, value<span class="op">=</span><span class="st">"#000000"</span>)</span>
<span id="cb13-28"><a href="#cb13-28" aria-hidden="true" tabindex="-1"></a>    brush_size <span class="op">=</span> Input(<span class="bu">type</span><span class="op">=</span><span class="st">"range"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"brush-size"</span>, <span class="bu">min</span><span class="op">=</span><span class="st">"1"</span>, <span class="bu">max</span><span class="op">=</span><span class="st">"50"</span>, value<span class="op">=</span><span class="st">"10"</span>)</span>
<span id="cb13-29"><a href="#cb13-29" aria-hidden="true" tabindex="-1"></a>    save_button <span class="op">=</span> Button(<span class="st">"Save Canvas"</span>, <span class="bu">id</span><span class="op">=</span><span class="st">"save-canvas"</span>, hx_post<span class="op">=</span><span class="ss">f"/rooms/</span><span class="sc">{</span><span class="bu">id</span><span class="sc">}</span><span class="ss">/save"</span>, hx_vals<span class="op">=</span><span class="st">"js:{canvas_data: JSON.stringify(canvas.toJSON())}"</span>)</span>
<span id="cb13-30"><a href="#cb13-30" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-31"><a href="#cb13-31" aria-hidden="true" tabindex="-1"></a>    js <span class="op">=</span> <span class="ss">f"""</span></span>
<span id="cb13-32"><a href="#cb13-32" aria-hidden="true" tabindex="-1"></a><span class="ss">    var canvas = new fabric.Canvas('canvas');</span></span>
<span id="cb13-33"><a href="#cb13-33" aria-hidden="true" tabindex="-1"></a><span class="ss">    canvas.isDrawingMode = true;</span></span>
<span id="cb13-34"><a href="#cb13-34" aria-hidden="true" tabindex="-1"></a><span class="ss">    canvas.freeDrawingBrush.color = '#000000';</span></span>
<span id="cb13-35"><a href="#cb13-35" aria-hidden="true" tabindex="-1"></a><span class="ss">    canvas.freeDrawingBrush.width = 10;</span></span>
<span id="cb13-36"><a href="#cb13-36" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-37"><a href="#cb13-37" aria-hidden="true" tabindex="-1"></a><span class="ss">    // Load existing canvas data</span></span>
<span id="cb13-38"><a href="#cb13-38" aria-hidden="true" tabindex="-1"></a><span class="ss">    fetch(`/rooms/</span><span class="sc">{</span><span class="bu">id</span><span class="sc">}</span><span class="ss">/load`)</span></span>
<span id="cb13-39"><a href="#cb13-39" aria-hidden="true" tabindex="-1"></a><span class="ss">    .then(response =&gt; response.json())</span></span>
<span id="cb13-40"><a href="#cb13-40" aria-hidden="true" tabindex="-1"></a><span class="ss">    .then(data =&gt; </span><span class="ch">{{</span></span>
<span id="cb13-41"><a href="#cb13-41" aria-hidden="true" tabindex="-1"></a><span class="ss">        if (data &amp;&amp; Object.keys(data).length &gt; 0) </span><span class="ch">{{</span></span>
<span id="cb13-42"><a href="#cb13-42" aria-hidden="true" tabindex="-1"></a><span class="ss">            canvas.loadFromJSON(data, canvas.renderAll.bind(canvas));</span></span>
<span id="cb13-43"><a href="#cb13-43" aria-hidden="true" tabindex="-1"></a><span class="ss">        </span><span class="ch">}}</span></span>
<span id="cb13-44"><a href="#cb13-44" aria-hidden="true" tabindex="-1"></a><span class="ss">    </span><span class="ch">}}</span><span class="ss">);</span></span>
<span id="cb13-45"><a href="#cb13-45" aria-hidden="true" tabindex="-1"></a><span class="ss">    </span></span>
<span id="cb13-46"><a href="#cb13-46" aria-hidden="true" tabindex="-1"></a><span class="ss">    document.getElementById('color-picker').onchange = function() </span><span class="ch">{{</span></span>
<span id="cb13-47"><a href="#cb13-47" aria-hidden="true" tabindex="-1"></a><span class="ss">        canvas.freeDrawingBrush.color = this.value;</span></span>
<span id="cb13-48"><a href="#cb13-48" aria-hidden="true" tabindex="-1"></a><span class="ss">    </span><span class="ch">}}</span><span class="ss">;</span></span>
<span id="cb13-49"><a href="#cb13-49" aria-hidden="true" tabindex="-1"></a><span class="ss">    </span></span>
<span id="cb13-50"><a href="#cb13-50" aria-hidden="true" tabindex="-1"></a><span class="ss">    document.getElementById('brush-size').oninput = function() </span><span class="ch">{{</span></span>
<span id="cb13-51"><a href="#cb13-51" aria-hidden="true" tabindex="-1"></a><span class="ss">        canvas.freeDrawingBrush.width = parseInt(this.value, 10);</span></span>
<span id="cb13-52"><a href="#cb13-52" aria-hidden="true" tabindex="-1"></a><span class="ss">    </span><span class="ch">}}</span><span class="ss">;</span></span>
<span id="cb13-53"><a href="#cb13-53" aria-hidden="true" tabindex="-1"></a><span class="ss">    """</span></span>
<span id="cb13-54"><a href="#cb13-54" aria-hidden="true" tabindex="-1"></a>    </span>
<span id="cb13-55"><a href="#cb13-55" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> Titled(<span class="ss">f"Room: </span><span class="sc">{</span>room<span class="sc">.</span>name<span class="sc">}</span><span class="ss">"</span>,</span>
<span id="cb13-56"><a href="#cb13-56" aria-hidden="true" tabindex="-1"></a>                  A(Button(<span class="st">"Leave Room"</span>), href<span class="op">=</span><span class="st">"/"</span>),</span>
<span id="cb13-57"><a href="#cb13-57" aria-hidden="true" tabindex="-1"></a>                  canvas,</span>
<span id="cb13-58"><a href="#cb13-58" aria-hidden="true" tabindex="-1"></a>                  Div(color_picker, brush_size, save_button),</span>
<span id="cb13-59"><a href="#cb13-59" aria-hidden="true" tabindex="-1"></a>                  Script(src<span class="op">=</span><span class="st">"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/5.3.1/fabric.min.js"</span>),</span>
<span id="cb13-60"><a href="#cb13-60" aria-hidden="true" tabindex="-1"></a>                  Script(js))</span>
<span id="cb13-61"><a href="#cb13-61" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-62"><a href="#cb13-62" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">/save"</span>)</span>
<span id="cb13-63"><a href="#cb13-63" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> post(<span class="bu">id</span>:<span class="bu">int</span>, canvas_data:<span class="bu">str</span>):</span>
<span id="cb13-64"><a href="#cb13-64" aria-hidden="true" tabindex="-1"></a>    rooms.update({<span class="st">'canvas_data'</span>: canvas_data}, <span class="bu">id</span>)</span>
<span id="cb13-65"><a href="#cb13-65" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="st">"Canvas saved successfully"</span></span>
<span id="cb13-66"><a href="#cb13-66" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-67"><a href="#cb13-67" aria-hidden="true" tabindex="-1"></a><span class="at">@rt</span>(<span class="st">"/rooms/</span><span class="sc">{id}</span><span class="st">/load"</span>)</span>
<span id="cb13-68"><a href="#cb13-68" aria-hidden="true" tabindex="-1"></a><span class="cf">async</span> <span class="kw">def</span> get(<span class="bu">id</span>:<span class="bu">int</span>):</span>
<span id="cb13-69"><a href="#cb13-69" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> rooms[<span class="bu">id</span>]</span>
<span id="cb13-70"><a href="#cb13-70" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> room.canvas_data <span class="cf">if</span> room.canvas_data <span class="cf">else</span> <span class="st">"</span><span class="sc">{}</span><span class="st">"</span></span>
<span id="cb13-71"><a href="#cb13-71" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-72"><a href="#cb13-72" aria-hidden="true" tabindex="-1"></a>serve()</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
</div>
</section>
</section>
<section id="deploying-to-railway" class="level3">
<h3 class="anchored" data-anchor-id="deploying-to-railway">Deploying to Railway</h3>
<p>You can deploy your website to a number of hosting providers, for this tutorial we’ll be using Railway. To get started, make sure you create an <a href="https://railway.app/">account</a> and install the <a href="https://docs.railway.app/guides/cli">Railway CLI</a>. Once installed, make sure to run <code>railway login</code> to log in to your account.</p>
<p>To make deploying your website as easy as possible, FastHTMl comes with a built in CLI tool that will handle most of the deployment process for you. To deploy your website, run the following command in your terminal in the root directory of your project:</p>
<div class="sourceCode" id="cb14"><pre class="sourceCode sh code-with-copy"><code class="sourceCode bash"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="ex">fh_railway_deploy</span> quickdraw</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
<div class="callout callout-style-default callout-note callout-titled">
<div class="callout-header d-flex align-content-center">
<div class="callout-icon-container">
<i class="callout-icon"></i>
</div>
<div class="callout-title-container flex-fill">
Note
</div>
</div>
<div class="callout-body-container callout-body">
<p>Your app must be located in a <code>main.py</code> file for this to work.</p>
</div>
</div>
</section>
<section id="conclusion-youre-a-fasthtml-artist-now" class="level3">
<h3 class="anchored" data-anchor-id="conclusion-youre-a-fasthtml-artist-now">Conclusion: You’re a FastHTML Artist Now! 🎨🚀</h3>
<p>Congratulations! You’ve just built a sleek, interactive web application using FastHTML. Let’s recap what we’ve learned:</p>
<ol type="1">
<li>FastHTML allows you to create dynamic web apps with minimal code.</li>
<li>We used FastHTML’s routing system to handle different pages and actions.</li>
<li>We integrated with a SQLite database to store room information and canvas data.</li>
<li>We utilized Fabric.js to create an interactive drawing canvas.</li>
<li>We implemented features like color picking, brush size adjustment, and canvas saving.</li>
<li>We used HTMX for seamless, partial page updates without full reloads.</li>
<li>We learned how to deploy our FastHTML application to Railway for easy hosting.</li>
</ol>
<p>You’ve taken your first steps into the world of FastHTML development. From here, the possibilities are endless! You could enhance the drawing app further by adding features like:</p>
<ul>
<li>Implementing different drawing tools (e.g., shapes, text)</li>
<li>Adding user authentication</li>
<li>Creating a gallery of saved drawings</li>
<li>Implementing real-time collaborative drawing using WebSockets</li>
</ul>
<p>Whatever you choose to build next, FastHTML has got your back. Now go forth and create something awesome! Happy coding! 🖼️🚀</p>


</section>
</section>

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