api-patterns

API Patterns Skill

REST API Design

Resource Naming

# Collection
GET    /api/v1/documents        # List documents
POST   /api/v1/documents        # Create document

# Single resource
GET    /api/v1/documents/{id}   # Get document
PUT    /api/v1/documents/{id}   # Replace document
PATCH  /api/v1/documents/{id}   # Update document
DELETE /api/v1/documents/{id}   # Delete document

# Nested resources
GET    /api/v1/users/{id}/documents  # User's documents

HTTP Status Codes

Code	Meaning	When to Use
200	OK	Successful GET/PUT/PATCH
201	Created	Successful POST
204	No Content	Successful DELETE
400	Bad Request	Invalid input
401	Unauthorized	Missing/invalid auth
403	Forbidden	No permission
404	Not Found	Resource doesn't exist
409	Conflict	Duplicate resource
422	Unprocessable	Validation error
429	Too Many Requests	Rate limited
500	Internal Error	Server error

Response Format

{
  "data": {
    "id": "123",
    "type": "document",
    "attributes": {
      "title": "Example",
      "content": "..."
    }
  },
  "meta": {
    "total": 100,
    "page": 1,
    "per_page": 10
  }
}

Error Response

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid input",
    "details": [
      {"field": "title", "message": "Title is required"},
      {"field": "limit", "message": "Must be between 1 and 100"}
    ]
  }
}

---

FastAPI Implementation

from fastapi import FastAPI, HTTPException, Query, Path
from pydantic import BaseModel, Field

app = FastAPI(title="RAG-MCP API", version="1.0.0")

class SearchRequest(BaseModel):
    query: str = Field(..., min_length=1, description="Search query")
    limit: int = Field(10, ge=1, le=100, description="Max results")

class SearchResult(BaseModel):
    id: str
    title: str
    score: float
    content: str

class SearchResponse(BaseModel):
    results: list[SearchResult]
    total: int

@app.post("/api/v1/search", response_model=SearchResponse)
async def search(request: SearchRequest):
    """Search the knowledge base.

    Args:
        request: Search parameters

    Returns:
        Search results with scores
    """
    try:
        results = await perform_search(request.query, request.limit)
        return SearchResponse(results=results, total=len(results))
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))