Timezone fixes to avoid future depreciation

Author: GitTimeraider

DATETIME_MODERNIZATION.md

@@ -0,0 +1,98 @@
+# DateTime Modernization Update
+
+## Summary
+Updated the Subscription Tracker codebase to use modern Python datetime practices by replacing deprecated `datetime.utcnow()` with `datetime.now(timezone.utc)`.
+
+## Changes Made
+
+### ✅ Files Updated
+
+1. **`app/webhooks.py`**
+   - Added `timezone` import
+   - Updated webhook timestamp generation
+   - Updated last_used timestamp tracking
+   - Fixed Discord, Slack, and Generic webhook timestamp formats
+
+2. **`app/currency.py`**
+   - Added `timezone` import
+   - Updated cache age calculations for currency rates
+   - Fixed timezone-aware datetime comparisons
+
+3. **`app/models.py`**
+   - Added `timezone` import
+   - Updated database column defaults for:
+     - `Webhook.created_at`
+     - `ExchangeRate.created_at`
+     - `PaymentMethod.created_at`
+   - Fixed `ExchangeRate.save_rates()` method
+
+### 🔧 Technical Details
+
+#### Before (Deprecated):
+```python
+datetime.utcnow()  # Returns naive datetime in UTC
+created_at = db.Column(db.DateTime, default=datetime.utcnow)
+```
+
+#### After (Modern):
+```python
+datetime.now(timezone.utc)  # Returns timezone-aware datetime in UTC
+created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
+```
+
+### 📝 Key Improvements
+
+1. **Timezone Awareness**: All UTC timestamps are now timezone-aware
+2. **Future Compatibility**: Avoids deprecation warnings in Python 3.12+
+3. **Database Compatibility**: Lambda functions ensure fresh timestamps per record
+4. **Consistency**: Uniform approach across all modules
+
+### 🔍 Remaining `datetime.now()` Usage
+
+The following `datetime.now()` calls remain unchanged as they are used for local time operations:
+
+- **Display formatting**: User-facing timestamp displays
+- **Local date comparisons**: Subscription expiry checks relative to user's local date
+- **Health check timestamps**: Application status timestamps
+- **Circuit breaker timestamps**: Internal timeout tracking
+
+These are intentionally kept as local time since they represent user-facing functionality or internal timers.
+
+### 🧪 Testing
+
+After this update, ensure:
+
+1. **Webhook timestamps** appear correctly in your webhook destinations
+2. **Database records** have proper created_at timestamps
+3. **Currency rate caching** works correctly with age calculations
+4. **No deprecation warnings** appear in Python 3.12+ environments
+
+### 🚀 Migration Notes
+
+This is a **forward-compatible** change:
+- Existing database records are unaffected
+- All new records will use timezone-aware timestamps
+- No data migration required
+- Backward compatible with existing functionality
+
+### 📚 References
+
+- [Python datetime documentation](https://docs.python.org/3/library/datetime.html)
+- [PEP 615 – Support for the IANA Time Zone Database](https://peps.python.org/pep-0615/)
+- [Python 3.12 datetime deprecations](https://docs.python.org/3.12/whatsnew/3.12.html#deprecated)
+
+## Verification
+
+Run the application and verify:
+```bash
+# No deprecation warnings should appear
+docker-compose up --build
+
+# Test webhook functionality
+./test-webhook.sh discord "your-webhook-url"
+
+# Check database timestamps are timezone-aware
+# (New records should have proper UTC timestamps)
+```
+
+This update ensures the Subscription Tracker remains compatible with current and future Python versions while maintaining all existing functionality.

app/currency.py

@@ -1,7 +1,7 @@
 import requests
 import json
 import os
-from datetime import datetime, date
+from datetime import datetime, date, timezone
 from flask import current_app
 import xml.etree.ElementTree as ET
 from decimal import Decimal, getcontext, InvalidOperation
@@ -60,7 +60,7 @@ def get_exchange_rates(self, base_currency: str = 'EUR', force_refresh: bool = F
         if not force_refresh and primary_provider:
             record = ExchangeRate.query.filter_by(date=date.today(), base_currency=base_currency, provider=primary_provider).first()
             if record:
-                age_min = (datetime.utcnow() - record.created_at).total_seconds() / 60.0
+                age_min = (datetime.now(timezone.utc) - record.created_at).total_seconds() / 60.0
                 if age_min <= refresh_minutes:
                     try:
                         self.last_provider = primary_provider
@@ -79,7 +79,7 @@ def get_exchange_rates(self, base_currency: str = 'EUR', force_refresh: bool = F
                 if not force_refresh:
                     cached = ExchangeRate.query.filter_by(date=date.today(), base_currency=base_currency, provider=provider).first()
                     if cached:
-                        age_min = (datetime.utcnow() - cached.created_at).total_seconds() / 60.0
+                        age_min = (datetime.now(timezone.utc) - cached.created_at).total_seconds() / 60.0
                         if age_min <= refresh_minutes:
                             try:
                                 self.last_provider = provider

app/models.py

@@ -1,4 +1,4 @@
-from datetime import datetime, date
+from datetime import datetime, date, timezone
 from flask_login import UserMixin
 from werkzeug.security import generate_password_hash, check_password_hash
 from app import db, login_manager
@@ -62,7 +62,7 @@ class Webhook(db.Model):
     custom_headers = db.Column(db.Text)  # JSON string for custom headers
     is_active = db.Column(db.Boolean, default=True)
     user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
-    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
     last_used = db.Column(db.DateTime)
 
     # Relationship
@@ -106,7 +106,7 @@ class ExchangeRate(db.Model):
     base_currency = db.Column(db.String(3), nullable=False, default='EUR')
     provider = db.Column(db.String(40), nullable=False, default='legacy')  # data source identifier
     rates_json = db.Column(db.Text, nullable=False)  # JSON string of exchange rates
-    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
 
     __table_args__ = (
         db.UniqueConstraint('date', 'base_currency', 'provider', name='uq_rate_date_base_provider'),
@@ -136,7 +136,7 @@ def save_rates(cls, rates, base_currency='EUR', provider='unknown'):
         existing_rate = cls.query.filter_by(date=today, base_currency=base_currency, provider=provider).first()
         if existing_rate:
             existing_rate.rates_json = json.dumps(rates)
-            existing_rate.created_at = datetime.utcnow()
+            existing_rate.created_at = datetime.now(timezone.utc)
         else:
             new_rate = cls(
                 date=today,
@@ -154,7 +154,7 @@ class PaymentMethod(db.Model):
     last_four = db.Column(db.String(4), nullable=True)
     notes = db.Column(db.Text, nullable=True)
     user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
-    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
 
     # Relationship back to user
     user = db.relationship('User', backref=db.backref('payment_methods', lazy=True))

app/webhooks.py

@@ -15,7 +15,7 @@
 import requests
 import json
 import logging
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Dict, List, Optional, Any
 from flask import current_app
 
@@ -58,7 +58,7 @@ def send(self, message: str, title: str = None, color: str = None) -> Dict[str,
             response.raise_for_status()
 
             # Update last_used timestamp
-            self.webhook.last_used = datetime.utcnow()
+            self.webhook.last_used = datetime.now(timezone.utc)
             from app import db
             db.session.commit()
 
@@ -111,7 +111,7 @@ def prepare_payload(self, message: str, title: str = None, color: str = None) ->
 
         embed = {
             "description": message,
-            "timestamp": datetime.utcnow().isoformat(),
+            "timestamp": datetime.now(timezone.utc).isoformat(),
             "footer": {
                 "text": "Subscription Tracker"
             }
@@ -151,7 +151,7 @@ def prepare_payload(self, message: str, title: str = None, color: str = None) ->
 
         attachment = {
             "text": message,
-            "ts": int(datetime.utcnow().timestamp()),
+            "ts": int(datetime.now(timezone.utc).timestamp()),
             "footer": "Subscription Tracker"
         }
 
@@ -239,7 +239,7 @@ class GenericWebhookSender(WebhookSender):
     def prepare_payload(self, message: str, title: str = None, color: str = None) -> Dict[str, Any]:
         payload = {
             "text": message,
-            "timestamp": datetime.utcnow().isoformat()
+            "timestamp": datetime.now(timezone.utc).isoformat()
         }
 
         if title: