Pass an array to custom validator Angular

Question

My template:

          <input mdInput
                 [mdAutocomplete]="auto"
                 [(ngModel)]="formData.areaName"
                 (keyup)="updateFilteredAreas(formData.areaName)"
                 class="form-control {{areaName.errors && (areaName.dirty || areaName.touched) ? 'failed-validation' : ''}}"
                 name="areaName"
                 #areaName="ngModel"
                 arrayIncludes="one,two,three"
                 required>

          <div *ngIf="areaName.errors && (areaName.dirty || areaName.touched)"
               [hidden]="!areaName.errors.arrayIncludes"
               class="validation-error">
            Please enter a value from the array
          </div>

My custom validator:

export class CustomValidators {

  public static arrayIncludes(arrayIncludes: string): ValidatorFn {
    return (control: AbstractControl): { [key: string]: any } => {
      if (isPresent(Validators.required(control))) {
        return null;
      }

      let arrayFromString = arrayIncludes.split(",");

      let value: string = control.value;

      return arrayFromString.includes(value) ?
        null :
        { arrayIncludes: { valid: false } };
    };
  }
}

Helper function:

function isPresent(obj) {
    return obj !== undefined && obj !== null;
}

Validation directive:

const ARRAY_INCLUDES_VALIDATOR = {
    provide: NG_VALIDATORS,
    useExisting: forwardRef(() => ArrayIncludesValidator),
    multi: true
};

@Directive({
  selector: '[arrayIncludes][ngControl],[arrayIncludes][ngFormControl],[arrayIncludes][ngModel]',
  providers: [ARRAY_INCLUDES_VALIDATOR]
})
export class ArrayIncludesValidator implements Validator {
  private _validator: any;

  constructor(@Attribute('arrayIncludes') arrayIncludes: string) {
    this._validator = CustomValidators.arrayIncludes(arrayIncludes);
  }

  public validate(control: AbstractControl): {[key: string]: any} { return this._validator(control); }
}

So far I can put a string as a value to the directive in template:

arrayIncludes="one,two,three"

and then convert the string to an array, with the result being that only "one", "two", "three" values are allowed. What I need is to pass an object from the controller to the directive, which is an array of objects. Those objects have propery "area.name", and each "area.name" is a valid input. When i use the syntax:

[arrayIncludes]="filteredAreas"

with "filteredAreas" being my object, the error I get is

Error: Template parse errors:
Can't bind to 'arrayIncludes' since it isn't a known property of 'input'. ("
                 name="areaName"
                 #areaName="ngModel"
                 [ERROR ->][arrayIncludes]="filteredAreas"
                 required>

"): ng:///RegistrationModule/ConsumerFormComponent.html@42:21

How do I refactor my custom validator to accept the object via a template. It must have something to do with the "@Input" decorator. My issue is very similar to this thread, however, it seems to lack the information I need.

yurzui · Accepted Answer · 2017-08-04 10:32:38Z

4

If you want to pass an object you should use @Input instead of @Attribute

@Directive({...})
export class ArrayIncludesValidator implements Validator {
  private _validator: any;

  @Input() arrayIncludes: any;

  ngOnInit() {
    this._validator = CustomValidators.arrayIncludes(this.arrayIncludes);
  }

  public validate(control: AbstractControl): {[key: string]: any} { return this._validator(control); }
}

answered Aug 4, 2017 at 10:32

yurzui

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