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import graphviz | |
import json | |
from tempfile import NamedTemporaryFile | |
import os | |
def generate_entity_relationship_diagram(json_input: str, output_format: str) -> str: | |
""" | |
Generates an Entity Relationship (ER) diagram from JSON input. | |
Args: | |
json_input (str): A JSON string describing the ER diagram structure. | |
It must follow the Expected JSON Format Example below. | |
output_format (str): The output format for the generated diagram. | |
Supported formats: "png" or "svg" | |
Expected JSON Format Example: | |
{ | |
"entities": [ | |
{ | |
"name": "Person", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "person_id", | |
"type": "primary_key" | |
}, | |
{ | |
"name": "first_name", | |
"type": "regular" | |
}, | |
{ | |
"name": "last_name", | |
"type": "regular" | |
}, | |
{ | |
"name": "birth_date", | |
"type": "regular" | |
}, | |
{ | |
"name": "age", | |
"type": "derived" | |
}, | |
{ | |
"name": "phone_numbers", | |
"type": "multivalued" | |
}, | |
{ | |
"name": "full_address", | |
"type": "composite" | |
} | |
] | |
}, | |
{ | |
"name": "Student", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "student_number", | |
"type": "regular" | |
}, | |
{ | |
"name": "enrollment_date", | |
"type": "regular" | |
}, | |
{ | |
"name": "gpa", | |
"type": "derived" | |
} | |
] | |
}, | |
{ | |
"name": "UndergraduateStudent", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "major", | |
"type": "regular" | |
}, | |
{ | |
"name": "expected_graduation", | |
"type": "regular" | |
}, | |
{ | |
"name": "credits_completed", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "GraduateStudent", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "thesis_topic", | |
"type": "regular" | |
}, | |
{ | |
"name": "advisor_id", | |
"type": "regular" | |
}, | |
{ | |
"name": "degree_type", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "Faculty", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "employee_number", | |
"type": "regular" | |
}, | |
{ | |
"name": "hire_date", | |
"type": "regular" | |
}, | |
{ | |
"name": "office_number", | |
"type": "regular" | |
}, | |
{ | |
"name": "years_of_service", | |
"type": "derived" | |
} | |
] | |
}, | |
{ | |
"name": "Professor", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "rank", | |
"type": "regular" | |
}, | |
{ | |
"name": "tenure_status", | |
"type": "regular" | |
}, | |
{ | |
"name": "research_areas", | |
"type": "multivalued" | |
} | |
] | |
}, | |
{ | |
"name": "Lecturer", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "contract_type", | |
"type": "regular" | |
}, | |
{ | |
"name": "courses_per_semester", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "Staff", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "position_title", | |
"type": "regular" | |
}, | |
{ | |
"name": "department_assigned", | |
"type": "regular" | |
}, | |
{ | |
"name": "salary_grade", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "AdministrativeStaff", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "access_level", | |
"type": "regular" | |
}, | |
{ | |
"name": "responsibilities", | |
"type": "multivalued" | |
} | |
] | |
}, | |
{ | |
"name": "TechnicalStaff", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "certifications", | |
"type": "multivalued" | |
}, | |
{ | |
"name": "equipment_assigned", | |
"type": "multivalued" | |
} | |
] | |
}, | |
{ | |
"name": "Vehicle", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "vehicle_id", | |
"type": "primary_key" | |
}, | |
{ | |
"name": "license_plate", | |
"type": "regular" | |
}, | |
{ | |
"name": "year", | |
"type": "regular" | |
}, | |
{ | |
"name": "current_value", | |
"type": "derived" | |
} | |
] | |
}, | |
{ | |
"name": "Car", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "doors", | |
"type": "regular" | |
}, | |
{ | |
"name": "fuel_type", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "Bus", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "capacity", | |
"type": "regular" | |
}, | |
{ | |
"name": "route_assigned", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "MaintenanceVehicle", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "equipment_type", | |
"type": "regular" | |
}, | |
{ | |
"name": "specialized_tools", | |
"type": "multivalued" | |
} | |
] | |
}, | |
{ | |
"name": "Course", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "course_id", | |
"type": "primary_key" | |
}, | |
{ | |
"name": "course_name", | |
"type": "regular" | |
}, | |
{ | |
"name": "credits", | |
"type": "regular" | |
} | |
] | |
}, | |
{ | |
"name": "Department", | |
"type": "strong", | |
"attributes": [ | |
{ | |
"name": "dept_id", | |
"type": "primary_key" | |
}, | |
{ | |
"name": "dept_name", | |
"type": "regular" | |
}, | |
{ | |
"name": "budget", | |
"type": "regular" | |
} | |
] | |
} | |
], | |
"relationships": [ | |
{ | |
"name": "PersonISA", | |
"type": "isa", | |
"parent": "Person", | |
"children": ["Student", "Faculty", "Staff"] | |
}, | |
{ | |
"name": "StudentISA", | |
"type": "isa", | |
"parent": "Student", | |
"children": ["UndergraduateStudent", "GraduateStudent"] | |
}, | |
{ | |
"name": "FacultyISA", | |
"type": "isa", | |
"parent": "Faculty", | |
"children": ["Professor", "Lecturer"] | |
}, | |
{ | |
"name": "StaffISA", | |
"type": "isa", | |
"parent": "Staff", | |
"children": ["AdministrativeStaff", "TechnicalStaff"] | |
}, | |
{ | |
"name": "VehicleISA", | |
"type": "isa", | |
"parent": "Vehicle", | |
"children": ["Car", "Bus", "MaintenanceVehicle"] | |
}, | |
{ | |
"name": "Enrolls", | |
"type": "regular", | |
"entities": ["Student", "Course"], | |
"cardinalities": { | |
"Student": "M", | |
"Course": "M" | |
}, | |
"attributes": [ | |
{ | |
"name": "semester" | |
}, | |
{ | |
"name": "year" | |
}, | |
{ | |
"name": "grade" | |
} | |
] | |
}, | |
{ | |
"name": "Teaches", | |
"type": "regular", | |
"entities": ["Faculty", "Course"], | |
"cardinalities": { | |
"Faculty": "M", | |
"Course": "M" | |
}, | |
"attributes": [ | |
{ | |
"name": "semester" | |
}, | |
{ | |
"name": "classroom" | |
} | |
] | |
}, | |
{ | |
"name": "WorksIn", | |
"type": "regular", | |
"entities": ["Faculty", "Department"], | |
"cardinalities": { | |
"Faculty": "M", | |
"Department": "1" | |
}, | |
"attributes": [ | |
{ | |
"name": "start_date" | |
} | |
] | |
}, | |
{ | |
"name": "Manages", | |
"type": "regular", | |
"entities": ["Staff", "Department"], | |
"cardinalities": { | |
"Staff": "M", | |
"Department": "M" | |
}, | |
"attributes": [ | |
{ | |
"name": "role" | |
} | |
] | |
}, | |
{ | |
"name": "Uses", | |
"type": "regular", | |
"entities": ["Staff", "Vehicle"], | |
"cardinalities": { | |
"Staff": "M", | |
"Vehicle": "M" | |
}, | |
"attributes": [ | |
{ | |
"name": "usage_date" | |
}, | |
{ | |
"name": "purpose" | |
} | |
] | |
} | |
] | |
} | |
Returns: | |
str: The filepath to the generated image file. | |
""" | |
try: | |
if not json_input.strip(): | |
return "Error: Empty input" | |
data = json.loads(json_input) | |
if 'entities' not in data: | |
raise ValueError("Missing required field: entities") | |
dot = graphviz.Graph(comment='ER Diagram', engine='neato') | |
dot.attr( | |
bgcolor='white', | |
pad='1.5', | |
overlap='false', | |
splines='true', | |
sep='+25', | |
esep='+15' | |
) | |
dot.attr('node', fontname='Arial', fontsize='10', color='#404040') | |
dot.attr('edge', fontname='Arial', fontsize='9', color='#4a4a4a') | |
entity_color = '#BEBEBE' | |
attribute_color = '#B8D4F1' | |
relationship_color = '#FFF9C4' | |
isa_color = '#A8E6CF' | |
font_color = 'black' | |
entities = data.get('entities', []) | |
relationships = data.get('relationships', []) | |
for entity in entities: | |
entity_name = entity.get('name') | |
entity_type = entity.get('type', 'strong') | |
attributes = entity.get('attributes', []) | |
if not entity_name: | |
continue | |
entity_color = '#BEBEBE' | |
if entity_type == 'weak': | |
dot.node( | |
entity_name, | |
entity_name, | |
shape='box', | |
style='filled,rounded', | |
fillcolor=entity_color, | |
fontcolor=font_color, | |
color='#404040', | |
penwidth='3', | |
width='1.8', | |
height='0.8', | |
fontsize='12' | |
) | |
else: | |
dot.node( | |
entity_name, | |
entity_name, | |
shape='box', | |
style='filled,rounded', | |
fillcolor=entity_color, | |
fontcolor=font_color, | |
color='#404040', | |
penwidth='1', | |
width='1.8', | |
height='0.8', | |
fontsize='12' | |
) | |
for i, attr in enumerate(attributes): | |
attr_name = attr.get('name', '') | |
attr_type = attr.get('type', 'regular') | |
attr_id = f"{entity_name}_attr_{i}" | |
attr_color = attribute_color | |
if attr_type == 'primary_key': | |
dot.node( | |
attr_id, | |
f'{attr_name} (PK)', | |
shape='ellipse', | |
style='filled,rounded', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
width='1.2', | |
height='0.6', | |
fontsize='10' | |
) | |
elif attr_type == 'partial_key': | |
dot.node( | |
attr_id, | |
f'{attr_name} (Partial)', | |
shape='ellipse', | |
style='filled,rounded,dashed', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
width='1.2', | |
height='0.6', | |
fontsize='10' | |
) | |
elif attr_type == 'multivalued': | |
dot.node( | |
attr_id, | |
attr_name, | |
shape='ellipse', | |
style='filled,rounded', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
penwidth='3', | |
width='1.2', | |
height='0.6', | |
fontsize='10' | |
) | |
elif attr_type == 'derived': | |
dot.node( | |
attr_id, | |
f'/{attr_name}/', | |
shape='ellipse', | |
style='filled,rounded,dashed', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
width='1.2', | |
height='0.6', | |
fontsize='10' | |
) | |
elif attr_type == 'composite': | |
dot.node( | |
attr_id, | |
attr_name, | |
shape='ellipse', | |
style='filled,rounded', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
width='1.2', | |
height='0.6', | |
fontsize='10' | |
) | |
else: | |
dot.node( | |
attr_id, | |
attr_name, | |
shape='ellipse', | |
style='filled,rounded', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
width='1.2', | |
height='0.6', | |
fontsize='10' | |
) | |
dot.edge(entity_name, attr_id, color='#4a4a4a', len='1.5') | |
for relationship in relationships: | |
rel_name = relationship.get('name') | |
rel_type = relationship.get('type', 'regular') | |
entities_involved = relationship.get('entities', []) | |
cardinalities = relationship.get('cardinalities', {}) | |
rel_attributes = relationship.get('attributes', []) | |
if not rel_name: | |
continue | |
if rel_type == 'isa': | |
parent = relationship.get('parent') | |
children = relationship.get('children', []) | |
if parent and children: | |
isa_id = f"isa_{rel_name}" | |
isa_color = isa_color | |
dot.node( | |
isa_id, | |
'ISA', | |
shape='triangle', | |
style='filled,rounded', | |
fillcolor=isa_color, | |
fontcolor=font_color, | |
color='#404040', | |
penwidth='2', | |
width='1.0', | |
height='0.8', | |
fontsize='10' | |
) | |
dot.edge(parent, isa_id, color='#4a4a4a', len='2.0') | |
for child in children: | |
dot.edge(isa_id, child, color='#4a4a4a', len='2.0') | |
elif len(entities_involved) >= 2: | |
rel_color = relationship_color | |
if rel_type == 'identifying': | |
dot.node( | |
rel_name, | |
rel_name, | |
shape='diamond', | |
style='filled,rounded', | |
fillcolor=rel_color, | |
fontcolor=font_color, | |
color='#404040', | |
penwidth='3', | |
width='1.8', | |
height='1.0', | |
fontsize='11' | |
) | |
else: | |
dot.node( | |
rel_name, | |
rel_name, | |
shape='diamond', | |
style='filled,rounded', | |
fillcolor=rel_color, | |
fontcolor=font_color, | |
color='#404040', | |
penwidth='1', | |
width='1.8', | |
height='1.0', | |
fontsize='11' | |
) | |
for j, attr in enumerate(rel_attributes): | |
attr_name = attr.get('name', '') | |
attr_id = f"{rel_name}_attr_{j}" | |
attr_color = attribute_color | |
dot.node( | |
attr_id, | |
attr_name, | |
shape='ellipse', | |
style='filled,rounded', | |
fillcolor=attr_color, | |
fontcolor=font_color, | |
color='#404040', | |
width='1.0', | |
height='0.5', | |
fontsize='9' | |
) | |
dot.edge(rel_name, attr_id, color='#4a4a4a', len='1.0') | |
for entity in entities_involved: | |
cardinality = cardinalities.get(entity, '1') | |
dot.edge( | |
entity, | |
rel_name, | |
label=f' {cardinality} ', | |
color='#4a4a4a', | |
len='2.5', | |
fontcolor='#4a4a4a', | |
fontsize='10' | |
) | |
with NamedTemporaryFile(delete=False, suffix=f'.{output_format}') as tmp: | |
dot.render(tmp.name, format=output_format, cleanup=True) | |
return f"{tmp.name}.{output_format}" | |
except json.JSONDecodeError: | |
return "Error: Invalid JSON format" | |
except Exception as e: | |
return f"Error: {str(e)}" |