[FEAT] Add ajv-errors support

Information

Add ajv-errors message customization support.

Ref: https://www.npmjs.com/package/ajv-errors Related: #833

Example

Configuration:

const Ajv = require("ajv").default
const ajv = new Ajv({allErrors: true})
// Ajv option allErrors is required
require("ajv-errors")(ajv /*, {singleError: true} */)

const schema = {
  type: "object",
  required: ["foo"],
  properties: {
    foo: {type: "integer"},
  },
  additionalProperties: false,
  errorMessage: "should be an object with an integer property foo only",
}

const validate = ajv.compile(schema)
console.log(validate({foo: "a", bar: 2})) // false
console.log(validate.errors) // processed errors

Output:

[
  {
    keyword: "errorMessage",
    message: "should be an object with an integer property foo only",
    // ...
    params: {
      errors: [
        {keyword: "additionalProperties", dataPath: "" /* , ... */},
        {keyword: "type", dataPath: ".foo" /* , ... */},
      ],
    },
  },
]

Solution

Example 1:

Expected json-schema:

{
  type: "object",
  required: ["foo"],
  properties: {
    foo: {type: "integer"},
  },
  additionalProperties: false,
  errorMessage: {
    type: "should be an object", // will not replace internal "type" error for the property "foo"
    required: "should have property foo",
    additionalProperties: "should not have properties other than foo",
  },
}

Solution using decorator:

import {ErrorMsg} from "@tsed/ajv";

@ErrorMsg({
   type: "should be an object", 
   required: "should have property foo",
   additionalProperties: "should not have properties other than foo"
})
export class MyModel {
    @Required()
    @Integer()
    foo: number;
}

Example 2

For keywords “required” and “dependencies” it is possible to specify different messages for different properties.

Expected json-schema:

{
  type: "object",
  required: ["foo", "bar"],
  properties: {
    foo: {type: "integer"},
    bar: {type: "string"},
  },
  errorMessage: {
    type: "should be an object", // will not replace internal "type" error for the property "foo"
    required: {
      foo: 'should have an integer property "foo"',
      bar: 'should have a string property "bar"',
    },
  },
}

Solution using decorator:

import {ErrorMsg, TypeMsg, RequiredMsg} from "@tsed/ajv";

@TypeMsg("should be an object") // shortcut to ErrorMessage({type: 'msg'})
export class MyModel {
    @Required()
    @Integer()
    @RequiredError('integer', 'should have an integer property "foo"')
    foo: number;
   
   @Required()
   @RequiredError("required", 'should have a string property "bar"')
   bar: string;
}

alternative that need a huge rework, but which is more elegant:

import {ErrorMsg, TypeMsg, RequiredMsg} from "@tsed/ajv";

@TypeError("should be an object") // shortcut to ErrorMessage({type: 'msg'})
export class MyModel {
    @Required()
    @Integer().Error( 'should have an integer property "foo"')

    foo: number;
   
   @Required().Error('is required')
   bar: string;
}

Example 3 - Default message

When the value of keyword errorMessage is an object you can specify a message that will be used if any error appears that is not specified by keywords/properties/items using _ property:

const schema = {
  type: "object",
  required: ["foo", "bar"],
  properties: {
      foo: {type: "integer", minimum: 2},
      bar: {type: "string", minLength: 2},
  },
  additionalProperties: false,
  errorMessage: {
    properties: {
      foo: "data.foo should be integer >= 2",
      bar: "data.bar should be string with length >= 2",
    },
    _: 'data should have properties "foo" and "bar" only',
  },
}

Solution using decorator:

import {TypeError, RequiredError, DefaultError} from "@tsed/ajv";

@DefaultMsg('data should have properties "foo" and "bar" only') // eq: ErrorMsg({_: "message"})
export class MyModel {
    @Required()
    @Integer()
    @RequiredError('should have an integer property "foo"')
    foo: number;
   
   @Required()
   @RequiredError('should have a string property "bar"')
   bar: string;
}

Acceptance criteria

• Decorators works on class and properties
• Decorators are correctly exported:
  • ErrorMsg
  • TypeError
  • RequiredError
  • DefaultError
• Ajv is correctly configured with ajv-errors (Edit https://github.com/TypedProject/tsed/blob/production/packages/ajv/src/services/Ajv.ts#L48)
• Documentation is up-to-date (model.md and ajv.md)
• Unit test cover correctly the decorators.
• Integration test cover the success and error cases.

[Romakita]

@silveoj PR to add @CustomKeys decorator https://github.com/TypedProject/tsed/pull/1238

[Romakita]

@silveoj Can you review this issue. You have more experience with the ajv-errors module 😃. Maybe I miss something!

@flexwie This story after reviewed by @silveoj can be implemented 😉. It’s a complete story. Here is the Ts.ED slack to discuss: https://join.slack.com/t/tsed-framework/shared_invite/zt-ljtmbq2u-ln3FoEd4m4Oe8rIJ1~WjdQ

See you Romain