Angular Material Stepper Component For Each Step

Question

I have a angular material linear stepper each step is a separate angular component containing a form which needs validation

The validation simply just isn't working. I can progress through to the next step without completing the form.

To illustrate what I mean I have created a condensed version on stackblitz.

The main things to look at (I think) is the create-profile.component.html

<mat-horizontal-stepper linear #stepper>
    <mat-step [stepControl]="frmStepOne">
        <ng-template matStepLabel>Step One Details</ng-template>
        <step-one-component></step-one-component>
    </mat-step>
    <mat-step [stepControl]="frmStepTwo">
        <ng-template matStepLabel>Step Two Details</ng-template>
        <step-two-component></step-two-component>
    </mat-step>
    <mat-step [stepControl]="frmStepThree">
        <ng-template matStepLabel>Step Three Details</ng-template>
        <step-three-component></step-three-component>
    </mat-step>
</mat-horizontal-stepper>

And each step-X-component

Here is the stackblitz. https://stackblitz.com/edit/angular-vpoj5j

Answer 1

The problem is in your CreateProfileComponent :

@Component({
    selector: 'create-profile-component',
    templateUrl: './create-profile.component.html'
})
export class CreateProfileComponent {

    frmStepOne: FormGroup;
    frmStepTwo: FormGroup;
    frmStepThree: FormGroup;

    constructor(private fb: FormBuilder) { }

}

There is no relation between your defined FormGroups in CreateProfileComponent and your stepper components. You tried to extend every StepComponent with CreateProfileComponent , but with this approach every StepComponent has its own instance of CreateProfileComponent and so their own FormGroup declaration.

To solve your problem you can declare template variables for every StepComponent in your html (starting with # ) and pass the formControl to [stepControl] :

<mat-horizontal-stepper linear #stepper>
    <mat-step [stepControl]="step1.frmStepOne">
        <ng-template matStepLabel>Step One Details</ng-template>
        <step-one-component #step1></step-one-component>
    </mat-step>
    <mat-step [stepControl]="step2.frmStepTwo">
        <ng-template matStepLabel>Step Two Details</ng-template>
        <step-two-component #step2></step-two-component>
    </mat-step>
    <mat-step [stepControl]="step3.frmStepThree">
        <ng-template matStepLabel>Step Three Details</ng-template>
        <step-three-component #step3></step-three-component>
    </mat-step>
</mat-horizontal-stepper>

Or you leave your html as it is and work with ViewChild() (my preferred approach):

@Component({
    selector: 'create-profile-component',
    templateUrl: './create-profile.component.html'
})

export class CreateProfileComponent {

    @ViewChild(StepOneComponent) stepOneComponent: StepOneComponent;
    @ViewChild(StepTwoComponent) stepTwoComponent: StepTwoComponent;
    @ViewChild(StepTwoComponent) stepThreeComponent: StepThreeComponent;

    get frmStepOne() {
       return this.stepOneComponent ? this.stepOneComponent.frmStepOne : null;
    }

    get frmStepTwo() {
       return this.stepTwoComponent ? this.stepTwoComponent.frmStepTwo : null;
    }

    get frmStepThree() {
       return this.stepThreeComponent ? this.stepThreeComponent.frmStepThree : null;
    }

}

Either way there is no need to extend your StepComponents with CreateProfileComponent and it doesn't make any sense.

@Component({
    selector: 'step-x-component',
    templateUrl: './step-x.component.html',
})
export class StepXComponent {

    public frmStepX: FormGroup;

    constructor(private formBuilder: FormBuilder) {
    }

    ngOnInit() {
        this.frmStepX = this.formBuilder.group({
            name: ['', Validators.required]
        });

    }

}

Answer 2

Your stepper and forms components works on different form objects. You need to set super's forms objects in step component's ngOnInit()

ngOnInit() {
    super.frmStepTwo = this.formBuilder.group({
        address: ['', Validators.required]
    });
}

instead

ngOnInit() {
    this.frmStepTwo = this.formBuilder.group({
        address: ['', Validators.required]
    });
}

Answer 3

To have a mat-stepper with each step as its own component, create the buttons to traverse through the stepper outside the component and show/hide the traversal buttons based on form validation done inside the individual component and expose the form info to the parent stepper.
For Example:

<mat-horizontal-stepper  #stepper linear  iseditable>
<mat-step 
 [stepControl]="firstFormGroup" 
 [completed]="primaryIsTrue"
 >
  <app-primary-settings  
  (formIsValid)="formValidity($event)"></app-primary-settings>

  <button mat-button matStepperNext 
   *ngIf="primaryIsTrue">
    Next
   </button>
</mat-step>

</mat-horizontal-stepper>