Add Materials for "A Close Look at a FastAPI Example Application"

Author: acsany

fastapi-python-web-apis/README.md

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+# A Close Look at a FastAPI Example Application
+
+This repository contains code snippets discussed in the associated tutorial on [A Close Look at a FastAPI Example Application](https://realpython.com/fastapi-python-web-apis/).
+
+## Installation
+
+The recommended way to install FastAPI is with the `[standard]` extra dependencies. This ensures you get all the tools you need for developing an API without having to hunt down additional packages later:
+
+```console
+$ python -m pip install "fastapi[standard]"
+```
+
+The quotes around `"fastapi[standard]"` ensure the command works correctly across different [terminals](https://realpython.com/terminal-commands/) and operating systems. With the command above you install several useful packages, including the [FastAPI CLI](https://fastapi.tiangolo.com/fastapi-cli/) and [uvicorn](https://www.uvicorn.org/), an ASGI server for running your application.
+
+You can also use the `requirements.txt` file in this folder and run `python -m pip install -r requirements.txt` to install the standard dependencies of FastAPI.

fastapi-python-web-apis/main.py

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+import random
+from string import ascii_letters, hexdigits
+from typing import Annotated
+
+from jinja2 import Template
+from pydantic import BaseModel, Field
+
+from fastapi import FastAPI, HTTPException, Query
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import HTMLResponse, PlainTextResponse
+
+tags_metadata = [
+    {
+        "name": "Random Playground",
+        "description": "Operations for generating random stuff",
+    },
+    {
+        "name": "Random Items Management",
+        "description": "Create, shuffle, read, update and delete items",
+    },
+]
+
+app = FastAPI(
+    title="Randomizer API",
+    description="Generate random numbers and manage a list of items",
+    version="1.0.0",
+    openapi_tags=tags_metadata,
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["http://localhost:3000", "https://example.com"],
+    allow_credentials=True,
+    allow_methods=["GET", "POST", "PUT", "DELETE"],
+    allow_headers=["*"],
+)
+
+items_db = []
+
+
+class Item(BaseModel):
+    name: str = Field(
+        min_length=1, max_length=100, description="The item name"
+    )
+
+
+class ItemList(BaseModel):
+    items: list[str] = Field(min_items=1, description="List of items")
+
+
+class ItemUpdate(BaseModel):
+    old_item: str = Field(min_length=1, description="Item to replace")
+    new_item: str = Field(min_length=1, description="New item name")
+
+
+class ItemResponse(BaseModel):
+    message: str
+    item: str
+    total_items: int
+
+
+class ItemListResponse(BaseModel):
+    original_order: list[str]
+    randomized_order: list[str]
+    count: int
+
+
+class ItemUpdateResponse(BaseModel):
+    message: str
+    old_item: str
+    new_item: str
+
+
+class ItemDeleteResponse(BaseModel):
+    message: str
+    deleted_item: str
+    remaining_items: int
+
+
+@app.get("/", tags=["Random Playground"])
+async def home():
+    return {"message": "Welcome to the Randomizer API"}
+
+
+@app.get("/random/{max_value}", tags=["Random Playground"])
+async def get_random_number(max_value: int):
+    return {"max": max_value, "random_number": random.randint(1, max_value)}
+
+
+@app.get("/random-between", tags=["Random Playground"])
+def get_random_number_between(
+    min_value: Annotated[
+        int | None,
+        Query(
+            title="Minimum Value",
+            description="The minimum random number",
+            ge=1,
+            le=99,
+        ),
+    ] = 1,
+    max_value: Annotated[
+        int | None,
+        Query(
+            title="Maximum Value",
+            description="The maximum random number",
+            ge=1,
+            le=1000,
+        ),
+    ] = 99,
+):
+    if min_value > max_value:
+        return {"error": "min_value cannot be greater than max_value"}
+
+    return {
+        "min": min_value,
+        "max": max_value,
+        "random_number": random.randint(min_value, max_value),
+    }
+
+
+@app.get("/random-string/{length}", tags=["Random Playground"])
+def generate_random_string(length: int):
+    return PlainTextResponse("".join(random.choices(ascii_letters, k=length)))
+
+
+@app.get(
+    "/random-color", response_class=HTMLResponse, tags=["Random Playground"]
+)
+def random_color():
+    hex_chars = "".join(random.choice(hexdigits.lower()) for _ in range(6))
+    hex_color = f"#{hex_chars}"
+    template_string = """
+    <!DOCTYPE html>
+    <html lang="en">
+    <head>
+        <meta charset="UTF-8">
+        <title>Random Color: {{ color }}</title>
+        <style>
+            body {
+                height: 100vh;
+                display: flex;
+                justify-content: center;
+                align-items: center;
+                background-color: {{ color }};
+                color: white;
+                font-size: 120px;
+                font-family: monospace;
+            }
+        </style>
+    </head>
+    <body>
+        <div>{{ color }}</div>
+    </body>
+    </html>
+    """
+
+    template = Template(template_string)
+    html_content = template.render(color=hex_color)
+
+    return html_content
+
+
+@app.post(
+    "/items", response_model=ItemResponse, tags=["Random Items Management"]
+)
+def add_item(item: Item):
+    if item.name in items_db:
+        raise HTTPException(status_code=400, detail="Item already exists")
+
+    items_db.append(item.name)
+    return ItemResponse(
+        message="Item added successfully",
+        item=item.name,
+        total_items=len(items_db),
+    )
+
+
+@app.get(
+    "/items/random",
+    response_model=ItemListResponse,
+    tags=["Random Items Management"],
+)
+def get_randomized_items():
+    if not items_db:
+        return ItemListResponse(
+            original_order=[], randomized_order=[], count=0
+        )
+
+    randomized = items_db.copy()
+    random.shuffle(randomized)
+
+    return ItemListResponse(
+        original_order=items_db,
+        randomized_order=randomized,
+        count=len(items_db),
+    )
+
+
+@app.put(
+    "/items",
+    response_model=ItemUpdateResponse,
+    tags=["Random Items Management"],
+)
+def update_item(item_update: ItemUpdate):
+    if item_update.old_item not in items_db:
+        raise HTTPException(status_code=404, detail="Item not found")
+
+    index = items_db.index(item_update.old_item)
+    items_db[index] = item_update.new_item
+
+    return ItemUpdateResponse(
+        message="Item updated successfully",
+        old_item=item_update.old_item,
+        new_item=item_update.new_item,
+    )
+
+
+@app.delete(
+    "/items/{item}",
+    response_model=ItemDeleteResponse,
+    tags=["Random Items Management"],
+)
+def delete_item(item: str):
+    if item not in items_db:
+        raise HTTPException(status_code=404, detail="Item not found")
+
+    items_db.remove(item)
+
+    return ItemDeleteResponse(
+        message="Item deleted successfully",
+        deleted_item=item,
+        remaining_items=len(items_db),
+    )

fastapi-python-web-apis/main_start.py

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+from fastapi import FastAPI
+
+app = FastAPI()
+
+items_db = []
+
+
+@app.get("/")
+def home():
+    return {"message": "Welcome to the Randomizer API"}
+
+
+@app.post("/items")
+def add_item(item: str):
+    if not item.strip():
+        raise HTTPException(status_code=400, detail="Item cannot be empty")
+
+    if item in items_db:
+        raise HTTPException(status_code=400, detail="Item already exists")
+
+    items_db.append(item)
+    return {
+        "message": "Item added successfully",
+        "item": item,
+        "total_items": len(items_db),
+    }

fastapi-python-web-apis/requirements.txt

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+annotated-types==0.7.0
+anyio==4.10.0
+certifi==2025.8.3
+click==8.2.1
+dnspython==2.7.0
+email_validator==2.2.0
+fastapi==0.116.1
+fastapi-cli==0.0.8
+fastapi-cloud-cli==0.1.5
+h11==0.16.0
+httpcore==1.0.9
+httptools==0.6.4
+httpx==0.28.1
+idna==3.10
+Jinja2==3.1.6
+markdown-it-py==4.0.0
+MarkupSafe==3.0.2
+mdurl==0.1.2
+pydantic==2.11.7
+pydantic_core==2.33.2
+Pygments==2.19.2
+python-dotenv==1.1.1
+python-multipart==0.0.20
+PyYAML==6.0.2
+rich==14.1.0
+rich-toolkit==0.15.0
+rignore==0.6.4
+sentry-sdk==2.34.1
+shellingham==1.5.4
+sniffio==1.3.1
+starlette==0.47.2
+typer==0.16.0
+typing-inspection==0.4.1
+typing_extensions==4.14.1
+urllib3==2.5.0
+uvicorn==0.35.0
+uvloop==0.21.0
+watchfiles==1.1.0
+websockets==15.0.1