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@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

Tests

Run npm test from the root folder.

Contributors

See all contributors.

License

MIT

LoopBack