@loopback/example-validation-app

An example application to demonstrate validation in LoopBack.

Summary

This application shows how to add validation in a LoopBack application. It exposes /coffee-shops endpoints to create/read/update/delete a CoffeeShop instance with the in-memory storage.

Key artifacts

1. CoffeeShop model: Shows how to add validation using AJV.

   Example to limit length on a string:

   @property({
    type: 'string',
    required: true,
    // Add jsonSchema
    jsonSchema: {
      maxLength: 10,
      minLength: 5,
      errorMessage: 'City name should be between 5 and 10 characters',
    },
   })
   city: string;

2. ValidatePhoneNumInterceptor: an interceptor for custom validation - it checks whether the area code of the phone number matches with the city name.

3. CoffeeShopController: controller where the ValidatePhoneNumInterceptor is applied.

4. MySequence: a custom sequence for creating custom error messages. This is not a requirement, just a demonstration of how to customize error messages during runtime.

Use

Start the app:

npm start

The application will listen on port 3000. Open http://localhost:3000/explorer in your browser. You can try to test the validation for the /coffee-shops endpoints.

Testing validation at work

When calling POST /coffee-shops API, there are a few ways to test validation is happening. An example of valid request body for CoffeeShop is:

{
  "city": "Toronto",
  "phoneNum": "416-111-1111",
  "capacity": 10
}

However, the following examples of request body are not valid, and you'll be getting an error with status code 422 and their corresponding error messages.

Example 1: CoffeeShop.city length exceeds limit of 10

{
  "city": "Toooooooooooronto",
  "phoneNum": "416-111-1111",
  "capacity": 10
}

Example 2: CoffeeShop.phoneNum pattern is not "xxx-xxx-xxxx"

{
  "city": "Toronto",
  "phoneNum": "4161111111",
  "capacity": 10
}

Example 3: CoffeeShop.capacity value exceeds the limit of 100

{
  "city": "Toronto",
  "phoneNum": "416-111-1111",
  "capacity": 10000
}

Example 4: CoffeeShop.phoneNum has area code not matching the city name

{
  "city": "Toronto",
  "phoneNum": "999-111-1111",
  "capacity": 10
}

According to the logic set in src/interceptors/validate-phone-num.interceptor.ts, if city name is Toronto, the area code for the phone number should begin with 416 or 647.

Contributions

• Guidelines
• Join the team

Tests

Run npm test from the root folder.

Contributors

See all contributors.

License

MIT