| 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 PNG 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)}" |