Fix JSON parsing in tree retrieval endpoints

- Fixed get_trees endpoint to properly parse JSON fields when retrieving from database
- Fixed get_tree endpoint to properly parse JSON fields for individual tree retrieval
- Both endpoints now convert stored JSON strings back to Python objects before response validation
- This resolves the ResponseValidationError when retrieving trees with utility/phenology data
- Trees can now be created, stored, and retrieved without validation errors

app.py

@@ -466,7 +466,33 @@ async def get_trees(
             params.extend([limit, offset])
 
             cursor.execute(query, params)
-            trees = [dict(row) for row in cursor.fetchall()]
+            rows = cursor.fetchall()
+            
+            # Parse JSON fields for each tree
+            trees = []
+            for row in rows:
+                tree_data = dict(row)
+                
+                # Parse JSON fields back to Python objects
+                if tree_data.get('utility'):
+                    try:
+                        tree_data['utility'] = json.loads(tree_data['utility'])
+                    except (json.JSONDecodeError, TypeError):
+                        tree_data['utility'] = None
+                        
+                if tree_data.get('phenology_stages'):
+                    try:
+                        tree_data['phenology_stages'] = json.loads(tree_data['phenology_stages'])
+                    except (json.JSONDecodeError, TypeError):
+                        tree_data['phenology_stages'] = None
+                        
+                if tree_data.get('photographs'):
+                    try:
+                        tree_data['photographs'] = json.loads(tree_data['photographs'])
+                    except (json.JSONDecodeError, TypeError):
+                        tree_data['photographs'] = None
+                        
+                trees.append(tree_data)
 
             logger.info(f"Retrieved {len(trees)} trees")
             return trees
@@ -566,7 +592,27 @@ async def get_tree(tree_id: int):
                     detail=f"Tree with ID {tree_id} not found",
                 )
 
-            return dict(tree)
+            # Parse JSON fields back to Python objects
+            tree_data = dict(tree)
+            if tree_data.get('utility'):
+                try:
+                    tree_data['utility'] = json.loads(tree_data['utility'])
+                except (json.JSONDecodeError, TypeError):
+                    tree_data['utility'] = None
+                    
+            if tree_data.get('phenology_stages'):
+                try:
+                    tree_data['phenology_stages'] = json.loads(tree_data['phenology_stages'])
+                except (json.JSONDecodeError, TypeError):
+                    tree_data['phenology_stages'] = None
+                    
+            if tree_data.get('photographs'):
+                try:
+                    tree_data['photographs'] = json.loads(tree_data['photographs'])
+                except (json.JSONDecodeError, TypeError):
+                    tree_data['photographs'] = None
+
+            return tree_data
 
     except HTTPException:
         raise