DatoCMS Plugin - Postcode Picker

A custom DatoCMS field extension plugin that allows users to select multiple postcodes with an autocomplete search interface. Uses GeoNames API to search for postcodes by postcode or city name.

Features

• 🔍 Autocomplete Search: Type to search for postcodes or city names
• 🏷️ Multiple Selection: Select multiple postcodes with an accessible multi-select interface
• 🌍 Configurable Country: Set the country code in plugin settings (defaults to Belgium)
• 🔑 GeoNames Username: Optional GeoNames username for higher rate limits
• 🌐 API-Based: Uses GeoNames API to fetch postcode data (no hardcoded data)

Installation

1. Build the plugin:

   npm install
   npm run build

2. Install the plugin in your DatoCMS project:

   • Go to your DatoCMS project settings
   • Navigate to Plugins
   • Click "Add a plugin" → "Install from URL" or upload the built plugin

Usage

1. Configure the plugin:

   • Go to Settings → Plugins → Postcode Picker
   • Enter your GeoNames username for higher rate limits (optional)
   • Set the country code (ISO 3166-1 alpha-2, e.g., BE, NL, FR)
   • Click "Save"
   • Get a free GeoNames account at https://www.geonames.org/login

2. Add the field extension to a field:

   • Add a new JSON field to your model
   • In the field settings, scroll to "Field extensions"
   • Click "Add field extension" and select "Postcode Picker"
   • Save the field

3. Use the picker:

   • When editing records, you'll see the postcode picker interface
   • Type to search for postcodes or city names
   • Select multiple postcodes from the dropdown
   • Selected postcodes are displayed as chips with format "City (Postcode)"
   • Remove selections by clicking the × on each chip

4. Data format:

   • Selected postcodes are stored as a JSON string: "[{\"postcode\":\"1000\",\"city\":\"Brussels\"},...]"
   • The field stores a stringified JSON array of objects with postcode and city properties

API Configuration

The plugin uses the GeoNames API (free tier). You can configure your GeoNames username in the plugin settings.

To get a GeoNames username:

1. Visit https://www.geonames.org/login
2. Create a free account
3. Enter your username in the plugin settings for higher rate limits

Development

# Install dependencies
npm install

# Start development server
npm run dev

# Build for production
npm run build

Data Format

Selected postcodes are stored as JSON:

[
  { "postcode": "1000", "city": "Brussels" },
  { "postcode": "2000", "city": "Antwerp" }
]

License

MIT