add code first file

CodeFirst/code_first.py

@@ -0,0 +1,110 @@
+from fastapi import FastAPI, HTTPException, Path, Query, status
+from pydantic import BaseModel, Field
+from typing import List, Optional
+
+app = FastAPI(
+    title="User Service API",
+    description="Simple CRUD API to demonstrate Code First OpenAPI generation with FastAPI",
+    version="1.0.0"
+)
+
+# --------------------
+# Models
+# --------------------
+
+class UserBase(BaseModel):
+    name: str = Field(..., example="Alice")
+    age: int = Field(..., example="22")
+    email: str = Field(..., example="alice@example.com")
+
+class UserCreate(UserBase):
+    pass
+
+class User(UserBase):
+    id: int = Field(..., example=1)
+
+# --------------------
+# Fake database
+# --------------------
+
+users_db: dict[int, User] = {}
+
+# --------------------
+# CRUD Endpoints
+# --------------------
+
+@app.post(
+    "/users",
+    response_model=User,
+    status_code=status.HTTP_201_CREATED,
+    summary="Create a new user",
+    description="Creates a new user and returns the created resource",
+    tags=["Users"]
+)
+def create_user(user: UserCreate):
+    user_id = len(users_db) + 1
+    new_user = User(id=user_id, **user.dict())
+    users_db[user_id] = new_user
+    return new_user
+
+
+@app.get(
+    "/users",
+    response_model=List[User],
+    summary="List all users",
+    description="Returns a list of all users",
+    tags=["Users"]
+)
+def list_users(
+    limit: int = Query(10, ge=1, le=100, description="Maximum number of users to return")
+):
+    return list(users_db.values())[:limit]
+
+
+@app.get(
+    "/users/{user_id}",
+    response_model=User,
+    summary="Get user by ID",
+    description="Returns a single user by its ID",
+    tags=["Users"]
+)
+def get_user(
+    user_id: int = Path(..., ge=1, description="The ID of the user")
+):
+    user = users_db.get(user_id)
+    if not user:
+        raise HTTPException(status_code=404, detail="User not found")
+    return user
+
+
+@app.put(
+    "/users/{user_id}",
+    response_model=User,
+    summary="Update a user",
+    description="Updates an existing user",
+    tags=["Users"]
+)
+def update_user(
+    user_id: int = Path(..., ge=1, description="The ID of the user"),
+    user: UserCreate = ...
+):
+    if user_id not in users_db:
+        raise HTTPException(status_code=404, detail="User not found")
+    updated_user = User(id=user_id, **user.dict())
+    users_db[user_id] = updated_user
+    return updated_user
+
+
+@app.delete(
+    "/users/{user_id}",
+    status_code=status.HTTP_204_NO_CONTENT,
+    summary="Delete a user",
+    description="Deletes a user by its ID",
+    tags=["Users"]
+)
+def delete_user(
+    user_id: int = Path(..., ge=1, description="The ID of the user")
+):
+    if user_id not in users_db:
+        raise HTTPException(status_code=404, detail="User not found")
+    del users_db[user_id]