CODEWITHSUNDEEP
angularangular5angular-reactive-forms
Maihan Nijat
Maihan Nijat

Reputation: 9344

How to fix Argument of type '"email"' is not assignable to parameter of type 'string[]' error?

The Angular 5 application works fine but I am getting the following error while building it with production. It also builds fine with ng build but not with ng build --prod.

Argument of type '"email"' is not assignable to parameter of type 'string[]'.

The code on the line:

<mat-form-field>
  <input matInput placeholder="Email" formControlName="email" required>
  <mat-error *ngIf="form.hasError('email', 'email') && !form.hasError('required', 'email')">
    Please enter a valid email address
  </mat-error>
  <mat-error *ngIf="form.hasError('required', 'email')">
    Email is <strong>required</strong>
  </mat-error>
</mat-form-field>

And form:

private createForm() {
  this.form = new FormGroup({
    email: new FormControl('', [Validators.required, Validators.email]),
    password: new FormControl('', Validators.required)
  });
}

Upvotes: 3

Views: 1267

Answers (1)

Daniel W Strimpel
Daniel W Strimpel

Reputation: 8470

I think that you need to wrap your second 'email' parameter in an array based on Angular's source code (line 520-526):

/**
 * Returns true if the control with the given path has the error specified. Otherwise
 * returns false.
 *
 * If no path is given, it checks for the error on the present control.
 */
hasError(errorCode: string, path?: string[]): boolean  { return !!this.getError(errorCode, path); }

I believe the reason that it actually works in your regular build is because although it technically is invalid, the code that eventually gets executed has a call signature that accepts Array<string|number> | string (line 37-56). 

function _find(control: AbstractControl, path: Array<string|number>| string, delimiter: string) {
    ...
}

Note: your templates are not ran through the typing system in non-AOT mode and hence this doesn't pop up until you do a --prod build.

Upvotes: 5

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