API design & gRPC
REST best practices, protobuf, API versioning, and backward-compatible service contracts.
Build a Bulk Array POST Mock Server in Python
Creates an HTTP mock server that accepts POST requests with a JSON array and returns incremental IDs for each item.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse
class MockHandler(BaseHTTPRequestHandler):
def do_POST(self):
if urlparse(self.path).path != "/bulk":
self.send_response(404)
self.end_headers()
return
cont…Build a Mock REST API with PUT and GET in Python
A minimal mock REST server implementing idempotent PUT for resource replacement and GET for retrieval, built with Python's http.server module.
from http.server import BaseHTTPRequestHandler, HTTPServer
import json
from urllib.parse import urlparse
mock_db = {}
class MockAPIHandler(BaseHTTPRequestHandler):
def do_PUT(self):
parsed = urlparse(self.path)
resource_id = parsed.path.strip("/").split("/")[-1]
content_length = int(self.…Create a Data Helper in Python for gRPC-style APIs
This code builds a simple DataHelper class that mimics gRPC request/response handling with in-memory storage, JSON serialization, and basic CRUD operations for beginners.
import json
from dataclasses import dataclass, asdict
from typing import Dict, Any
@dataclass
class User:
user_id: int
name: str
email: str
class DataHelper:
"""Simple helper to demonstrate gRPC-like data handling for beginners."""
def __init__(self) -> None:
self._users: Dict[int, Use…How to Add HATEOAS Links to a Python API Response
Build a Python API resource class that adds self and next HATEOAS links to JSON responses, with a mock example for pagination.
import json
class Resource:
def __init__(self, name, data, next_page=None):
self.links = {"self": f"/api/resources/{name}"}
if next_page is not None:
self.links["next"] = f"/api/resources?page={next_page}"
self.data = data
def to_dict(self):
return {"links": self.…How to Build Cursor Pagination with Next and Prev Tokens in Python
A minimal cursor pagination implementation that returns next and previous cursor tokens for navigating a dataset.
from pprint import pprint
def make_cursor(page):
return f"page:{page:04d}"
def parse_cursor(cursor):
_, page = cursor.split(":", 1)
return int(page)
def paginate(all_items, page_size, cursor=None):
start = parse_cursor(cursor) if cursor else 0
end = start + page_size
items = all_items[sta…How to Build a Batch Operations Multi-Status 207 Mock Server in Python
Build a mock HTTP server that accepts a batch of operations and returns HTTP 207 Multi-Status with per-operation status codes in JSON.
from http.server import BaseHTTPRequestHandler, HTTPServer
import json
class BatchHandler(BaseHTTPRequestHandler):
def do_POST(self):
if self.path != "/batch":
self.send_response(404)
self.end_headers()
return
content_length = int(self.headers.get("Content-Leng…How to Build a Data Helper Class in Python for Beginners
Create a beginner-friendly DataHelper class that stores, retrieves, filters, and summarizes records in a list of dictionaries.
from __future__ import annotations
import json
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional
@dataclass
class DataHelper:
"""A beginner-friendly helper for common data tasks."""
data: List[Dict[str, Any]] = field(default_factory=list)
def add_record(self, record…How to Build a Hypermedia Collection Resource in Python
Creates a paginated hypermedia collection resource with HATEOAS links and embedded items.
import json
import math
class HypermediaCollection:
"""A mock hypermedia collection resource."""
def __init__(self, items, base_url="/api/items"):
self.items = items
self.base_url = base_url
def to_dict(self, page=1, per_page=3):
total = len(self.items)
pages = math.ceil…How to Build a Mock REST GET Endpoint Handler in Python
Create a lightweight mock REST GET server in Python using the standard library, with a dict-based route registry that maps paths to handler functions and returns JSON responses with proper HTTP status codes.
from http.server import BaseHTTPRequestHandler, HTTPServer
import json
# Mock API handler registry
def handle_users():
return {"status": "ok", "data": [{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}]}
def handle_products():
return {"status": "ok", "data": [{"id": 101, "name": "Laptop", "price": 999.99}…How to Build a Simple Data Helper in Python for API Design
Create a beginner-friendly DataHelper class that demonstrates basic CRUD operations (add, get, list, remove) using an in-memory dictionary, ideal for learning API design concepts.
class DataHelper:
"""Simple data helper for beginners learning API design concepts."""
def __init__(self):
self._data = {}
def add_record(self, key, value):
"""Add a record to the store."""
self._data[key] = value
return f"Added: {key} -> {value}"
def get_…How to Build a Simple Filter Helper in Python for API Design
Create a reusable data filter service with dataclasses that mimics gRPC request/response patterns for filtering dataset records.
from dataclasses import dataclass, field
from typing import List, Optional, Dict, Any
@dataclass
class FilterRequest:
"""A simple filter request mirroring a gRPC message structure."""
field_name: str
operator: str # eq, ne, gt, lt, contains
value: Any
page_size: int = 10
page_token: Optional…How to Build a Simple gRPC-Style Data Service in Python
Create a beginner-friendly gRPC-style service with dataclasses to simulate GetUser and CreateUser RPCs.
from dataclasses import dataclass
from typing import Optional
@dataclass
class User:
id: int
name: str
email: str
class UserService:
"""Simple gRPC-style service contract for beginner learners."""
def get_user(self, user_id: int) -> Optional[User]:
"""Simulated gRPC GetUser RPC."""
…How to Build a WebSocket Echo Server in Python with asyncio
Create a simple WebSocket echo server using the websockets library and asyncio to handle concurrent connections.
import asyncio
import websockets
async def echo(websocket):
async for message in websocket:
await websocket.send(f"Echo: {message}")
async def main():
async with websockets.serve(echo, "localhost", 8765):
print("WebSocket server started on ws://localhost:8765")
await asyncio.Future() …How to Build an Idempotency-Key POST Handler in Python
Python HTTP server mock that accepts POST requests and deduplicates them using an Idempotency-Key header, returning the same response for repeated calls.
import hashlib
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse
class MockAPI(BaseHTTPRequestHandler):
responses = {}
def do_POST(self):
length = int(self.headers.get("Content-Length", 0))
body = self.rfile.read(length).decode("utf-8")
…How to Implement Content Negotiation with JSON and XML in Python
Build an HTTP server that returns JSON or XML responses based on the client's Accept header, with a 406 response for unsupported formats.
import json
import xml.etree.ElementTree as ET
from http.server import BaseHTTPRequestHandler, HTTPServer
class RequestHandler(BaseHTTPRequestHandler):
def do_GET(self):
data = {"message": "Hello, world!"}
accept_header = self.headers.get("Accept", "")
if "application/json" in accept_hea…How to Implement ETag Optimistic Concurrency in Python
Build a lightweight in-memory resource store that uses MD5 hash ETags to prevent lost updates via optimistic concurrency control.
import hashlib
import json
class ResourceStore:
def __init__(self):
self.data = {}
self.etags = {}
def get(self, resource_id):
if resource_id not in self.data:
return None, None
return self.data[resource_id], self.etags[resource_id]
def put(self, resource_id, …How to Implement RBAC Permission Checks with a Route Decorator in Python
Build a reusable Python decorator that checks a user's role against allowed roles and raises a custom PermissionError when access is denied.
from functools import wraps
from enum import Enum
class Role(Enum):
ADMIN = "admin"
MODERATOR = "moderator"
USER = "user"
class PermissionError(Exception):
pass
def require_role(*allowed_roles):
def decorator(func):
@wraps(func)
def wrapper(user_role, *args, **kwargs):
…How to Mock a 202 Accepted Long-Running Operation in Python
Build a mock HTTP server that returns a 202 Accepted response immediately and simulates a long-running operation in the background with threading.
import time
import threading
from http.server import HTTPServer, BaseHTTPRequestHandler
class MockHandler(BaseHTTPRequestHandler):
def do_POST(self):
if self.path == "/long-running":
self.send_response(202)
self.send_header("Content-Type", "application/json")
self.end_h…How to Mock a Chunked Encoding Streaming Response in Python
Build a local mock HTTP server with Python's http.server that streams a chunked-encoded response with a 0.5s delay per chunk.
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
import time
class ChunkedHandler(BaseHTTPRequestHandler):
protocol_version = "HTTP/1.1"
def do_GET(self):
self.send_response(200)
self.send_header("Content-Type", "text/plain")
self.send_header("Transfer-Encoding", "c…How to Parse gRPC Request Data in Python
Build a beginner-friendly gRPC service handler that parses incoming protobuf messages into Python dictionaries and starts a simple gRPC server.
from google.protobuf import json_format
import grpc
from concurrent import futures
import time
class DataParsingService:
def parse(self, request):
return {
"received_json": json_format.MessageToJson(request),
"parsed_fields": {
"name": request.name,
…How to Prefix Python API URIs with a Version Slug
Build a versioned API endpoint by optionally adding a version prefix like v1 to the URL path using the stdlib urllib module.
from urllib.parse import urlparse
BASE_URL = "https://api.example.com"
def build_uri(resource, version="v1"):
"""Mock a versioned API URI with an optional v1 prefix."""
parsed = urlparse(BASE_URL)
prefix = f"/{version}" if version else ""
return f"{parsed.scheme}://{parsed.netloc}{prefix}/{resource.l…How to Validate Request Body JSON Against a Schema in Python
Build a lightweight schema validator to check required fields, types, string lengths, allowed values, and nested objects in a JSON request body.
import json
def validate_against_schema(data, schema, path=""):
errors = []
if not isinstance(data, dict):
errors.append(f"{path}: expected object, got {type(data).__name__}")
return errors
for field, rules in schema.items():
field_path = f"{path}.{field}" if path else field
…Version API by Accept Header with Vendor Media Types in Python
Build a mock HTTP server that routes to API versions by parsing vendor-specific Accept headers in Python.
from http.client import HTTPMessage
from http.server import BaseHTTPRequestHandler, HTTPServer
class VendorVersionHandler(BaseHTTPRequestHandler):
def do_GET(self):
accept = self.headers.get("Accept", "")
version = "v1"
if "application/vnd.myapi.v2+json" in accept:
version = "…Browse by section
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API design & gRPC — Python code examples
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