Middleware

Overview

The middleware module provides utilities for:

• Global request access
• Request timing and profiling
• User agent parsing
• Host validation
• Error handling
• Timezone detection

Global Request Access

Access request anywhere in your code without passing it explicitly:

from htk.middleware.classes import GlobalRequestMiddleware
from htk.middleware.utils import get_current_request

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.GlobalRequestMiddleware',
    # ...
]

# Access request globally
def some_function():
    request = get_current_request()
    user = request.user
    host = request.get_host()

Use Cases: - Access request in utility functions - Log request context in debugging - Track request metadata

User Agent Parsing

Automatically parse and expose user agent info:

from htk.middleware.classes import UserAgentMiddleware

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.UserAgentMiddleware',
    # ...
]

# Access in views
def my_view(request):
    user_agent = request.user_agent
    # {
    #   'is_mobile': True/False,
    #   'is_bot': True/False,
    #   'browser': 'Chrome',
    #   'os': 'Windows',
    #   'device': 'Desktop',
    # }

Request Timing

Measure request processing time:

from htk.middleware.classes import RequestTimerMiddleware

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.RequestTimerMiddleware',
    # ...
]

# View processing time in response headers
# X-Request-Time: 0.234 seconds

Useful for: - Performance monitoring - Identifying slow views - A/B testing performance - APM integration

Host Validation

Validate requests against allowed hosts:

from htk.middleware.classes import AllowedHostsMiddleware

# settings.py
ALLOWED_HOST_REGEXPS = [
    r'^example\.com$',
    r'^subdomain\.example\.com$',
    r'^localhost$',
]

# Enable middleware
MIDDLEWARE = [
    'htk.middleware.classes.AllowedHostsMiddleware',
    # ...
]

Error Handling

Gracefully handle custom HTTP errors:

from htk.middleware.classes import HttpErrorResponseMiddleware
from htk.utils.http.errors import HttpErrorResponseError

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.HttpErrorResponseMiddleware',
    # ...
]

# Raise errors in views
def api_endpoint(request):
    if not request.user.is_authenticated:
        raise HttpErrorResponseError(401, 'Unauthorized')
    # ...

# Middleware catches and formats response
# Returns: {'error': 'Unauthorized'} with 401 status

JSON Content-Type Handling

Fix JSON response content type for IE compatibility:

from htk.middleware.classes import RewriteJsonResponseContentTypeMiddleware

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.RewriteJsonResponseContentTypeMiddleware',
    # ...
]

# Ensures application/json content type (not text/html)

Timezone Detection

Auto-detect and set user timezone:

from htk.middleware.classes import TimezoneMiddleware

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.TimezoneMiddleware',
    # ...
]

# Automatically detects timezone from IP or user profile
# Sets timezone for datetime operations

Request Data Limits

Prevent overly large requests:

from htk.middleware.classes import RequestDataTooBigMiddleware

# Enable in settings.py
MIDDLEWARE = [
    'htk.middleware.classes.RequestDataTooBigMiddleware',
    # ...
]

# Returns 413 Payload Too Large if request exceeds limit

Complete Example

# settings.py
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',

    # HTK middleware
    'htk.middleware.classes.GlobalRequestMiddleware',
    'htk.middleware.classes.UserAgentMiddleware',
    'htk.middleware.classes.RequestTimerMiddleware',
    'htk.middleware.classes.TimezoneMiddleware',
    'htk.middleware.classes.AllowedHostsMiddleware',
    'htk.middleware.classes.RewriteJsonResponseContentTypeMiddleware',
    'htk.middleware.classes.HttpErrorResponseMiddleware',
    'htk.middleware.classes.RequestDataTooBigMiddleware',

    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ALLOWED_HOST_REGEXPS = [
    r'^example\.com$',
    r'^www\.example\.com$',
]

Best Practices

1. Order matters - Place middleware in logical order
2. Global request - Use sparingly, not a replacement for passing request
3. Timezone handling - Configure with user locale data
4. Error responses - Use HttpErrorResponseError for API errors
5. Performance - Monitor with RequestTimerMiddleware

Classes

• GlobalRequestMiddleware - Store request in thread-local storage
• UserAgentMiddleware - Parse and expose user agent data
• RequestTimerMiddleware - Measure request processing time
• AllowedHostsMiddleware - Validate host against regex patterns
• HttpErrorResponseMiddleware - Handle custom HTTP errors
• RewriteJsonResponseContentTypeMiddleware - Fix JSON content type
• TimezoneMiddleware - Auto-detect user timezone
• RequestDataTooBigMiddleware - Enforce request size limits