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.…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 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 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 Filter Query Parameters by Operator in Python
Parse a URL query string and keep only parameters with allowed comparison operators like eq, gt, and lt.
from urllib.parse import urlparse, parse_qs
def filter_operators(query_string, allowed=("eq", "gt", "lt")):
parsed = urlparse(query_string)
params = parse_qs(parsed.query)
filtered = {}
for key, values in params.items():
if "__" in key:
field, op = key.rsplit("__", 1)
i…How to Handle Retry-After Header in Python
Parse the Retry-After header from rate-limited API responses and implement retry logic with proper delays in Python.
```python
import time
from datetime import datetime, timedelta
class RetryAfterHandler:
def __init__(self, max_retries=3):
self.max_retries = max_retries
def get_retry_after_seconds(self, response_headers):
retry_after_value = response_headers.get("Retry-After")
if retry_after_value …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 Mock OAuth2 Bearer Token Auth Middleware in Python
Create a simple OAuth2 bearer token authentication middleware that verifies signed tokens and enforces scope-based access control.
import hmac
import time
import base64
import json
from functools import wraps
VALID_TOKENS = {"test_token_123": {"user": "alice", "scope": "read:posts"}}
def generate_token(username: str) -> str:
payload = {"user": username, "iat": int(time.time())}
encoded = base64.urlsafe_b64encode(json.dumps(payload).enc…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 Mock a Webhook Subscribe Callback URL in Python
Mock a webhook subscribe callback URL using Python's http.server to receive and parse POST requests sent by webhook providers.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
class WebhookHandler(BaseHTTPRequestHandler):
def do_POST(self):
content_length = int(self.headers.get('Content-Length', 0))
payload = json.loads(self.rfile.read(content_length)) if content_length else {}
print…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
…Implement If-Match Precondition Update in Python
A mock resource store that uses the If-Match header's ETag to guard updates, preventing overwrites from stale clients.
from dataclasses import dataclass
from typing import Optional
@dataclass
class Resource:
id: str
version: int = 1
data: str = ""
etag: str = "etag-1"
class MockResourceStore:
def __init__(self):
self.resources = {}
def update(self, resource_id: str, new_data: str, if_match: Optiona…Verify Webhook HMAC Signatures in Python
Create and verify HMAC-SHA256 signatures for webhook payloads using Python's hmac module, protecting against tampering.
import hashlib
import hmac
import json
SECRET = b"super-secret-webhook-key"
def create_signature(payload: bytes) -> str:
return hmac.new(SECRET, payload, hashlib.sha256).hexdigest()
def verify_signature(payload: bytes, signature: str) -> bool:
expected = create_signature(payload)
return hmac.compare_dig…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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