Lesson 2: Weather Tracker Blueprint with API Integration

Weather Tracker Feature Overview

The weather blueprint allows users to:

• Add cities to track (e.g., Macon, Georgia)
• Store city and temperature data in a local database
• Update temperatures by fetching live data from a weather API
• View current weather for all tracked locations

Example: Add "Macon, Georgia" with an initial temperature of 15°. Click "Update Weather" and it will fetch the actual current temperature (e.g., 82°).

Database Schema

Create a weather table with the following columns:

• weather_id: Integer, Primary Key, Auto-increment
• city: Text (e.g., 'Macon')
• state: Text (e.g., 'Georgia') - optional but helpful
• temperature: Integer or Real (current temperature in degrees)

Blueprint Routes

Your weather blueprint should have these routes:

@weather_bp.route('/weather')
def index():
    # Display all weather records

@weather_bp.route('/weather/add', methods=['POST'])
def add_weather():
    # Add new city to database

@weather_bp.route('/weather/update/<int:weather_id>')
def update_weather(weather_id):
    # Fetch live weather from API and update database

Weather API Integration

Use weather.gov (National Weather Service API) - completely free, no API key required!

The NWS API requires a two-step process:

1. Get the grid coordinates for a location
2. Fetch the forecast for those coordinates

Example API call to fetch temperature:

import requests

def get_temperature(city, state):
    # Step 1: Get coordinates (you can also hardcode these)
    geocode_url = f'https://nominatim.openstreetmap.org/search'
    params = {'q': f'{city}, {state}', 'format': 'json'}
    geo_response = requests.get(geocode_url, params=params)
    location = geo_response.json()[0]
    lat, lon = location['lat'], location['lon']
    
    # Step 2: Get weather from NWS
    points_url = f'https://api.weather.gov/points/{lat},{lon}'
    points_response = requests.get(points_url)
    forecast_url = points_response.json()['properties']['forecast']
    
    # Step 3: Get the forecast
    forecast_response = requests.get(forecast_url)
    current_temp = forecast_response.json()['properties']['periods'][0]['temperature']
    return current_temp

Why weather.gov?

• 100% free, no API key needed
• Official US government data
• No rate limits for reasonable use
• US locations only

Form Implementation

Create an HTML form to add new weather locations:

<form action="/weather/add" method="POST">
    <input type="text" name="city" 
           placeholder="City (e.g., Macon)" required>
    <input type="text" name="state" 
           placeholder="State (e.g., Georgia)">
    <input type="number" name="temperature" 
           placeholder="Initial Temperature">
    <button type="submit">Add Weather Record</button>
</form>

Update Weather Functionality

When a user clicks 'Update Weather' for a city:

1. Retrieve the city and state from the database
2. Make an API request to get the current temperature
3. Update the database record with the live temperature
4. Redirect back to the weather page to display updated information

Note: Make sure to handle API errors gracefully (e.g., city not found, API rate limit exceeded).