JSON To Pydantic

JSON to Pydantic Skill

This skill helps convert raw JSON data or API responses into structured, strongly-typed Python classes using Pydantic.

Instructions

1. Analyze the Input: Look at the JSON object provided by the user.

2. Infer Types:

   • string -> str
   • number -> int or float
   • boolean -> bool
   • array -> List[Type]
   • null -> Optional[Type]
   • Nested Objects -> Create a separate sub-class.

3. Follow the Example: Review examples/ to see how to structure the output code. notice how nested dictionaries like preferences are extracted into their own class.

   • Input: examples/input_data.json
   • Output: examples/output_model.py

Style Guidelines

• Use PascalCase for class names.
• Use type hints (List, Optional) from typing module.
• If a field can be missing or null, default it to None.

Outputs & Deliverables

• Primary Output: Python Pydantic models with complete type annotations
• Secondary Output: Validation rules and field defaults
• Success Criteria: Models match JSON structure and include proper type hints
• Quality Gate: Ready for integration into implementer's codebase

Constraints

• NO business logic. Data models only.
• NO implementation code beyond model definitions.
• Must handle nested objects and optional fields correctly.

Common Pitfalls

• Ignoring Nested Structures: Not extracting nested objects into separate classes creates monolithic models. Always decompose; create sub-classes for nested dicts.
• Wrong Type Inference: Confusing null with missing fields. null = Optional, missing entirely = Field with default_factory. Be precise.
• Generic Field Names: Using data, value, result instead of domain-specific names. Use the field name from JSON.
• Skipping Validation: Not adding constraints like Field(min_length=1) or regex patterns. Add validation rules to the model.
• Mixing Array Element Types: Not using Union types when arrays can contain multiple types. Use generics correctly.
• Missing Aliases: Not mapping JSON camelCase to Python snake_case with Field aliases. Handle naming convention mismatches explicitly.

Integration Points