Skills Development Defining Clean API Contracts With Pydantic Models

Defining Clean API Contracts With Pydantic Models

v20260423
pydantic-models-py
This skill demonstrates the multi-model pattern for creating robust and clean API contracts using Pydantic. It guides the creation of separate models for creation requests (Create), updates (Update), responses (Response), and database documents (InDB), ensuring type safety and clear data validation for Python backends. It also covers best practices like handling camelCase aliases and optional fields.
Get Skill
147 downloads
Overview

Pydantic Models

Create Pydantic models following the multi-model pattern for clean API contracts.

Quick Start

Copy the template from assets/template.py and replace placeholders:

  • {{ResourceName}} → PascalCase name (e.g., Project)
  • {{resource_name}} → snake_case name (e.g., project)

Multi-Model Pattern

Model Purpose
Base Common fields shared across models
Create Request body for creation (required fields)
Update Request body for updates (all optional)
Response API response with all fields
InDB Database document with doc_type

camelCase Aliases

class MyModel(BaseModel):
    workspace_id: str = Field(..., alias="workspaceId")
    created_at: datetime = Field(..., alias="createdAt")
    
    class Config:
        populate_by_name = True  # Accept both snake_case and camelCase

Optional Update Fields

class MyUpdate(BaseModel):
    """All fields optional for PATCH requests."""
    name: Optional[str] = Field(None, min_length=1)
    description: Optional[str] = None

Database Document

class MyInDB(MyResponse):
    """Adds doc_type for Cosmos DB queries."""
    doc_type: str = "my_resource"

Integration Steps

  1. Create models in src/backend/app/models/
  2. Export from src/backend/app/models/__init__.py
  3. Add corresponding TypeScript types

When to Use

This skill is applicable to execute the workflow or actions described in the overview.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
Info
Category Development
Name pydantic-models-py
Version v20260423
Size 1.97KB
Updated At 2026-04-24
Language