Using separate components in a linear mat-horizontal-stepper

Question

In Angular, is it possible to have a linear stepper where the individual steps are separate components? For example:

<mat-horizontal-stepper [linear]="isLinear">
    <mat-step [stepControl]="firstFormGroup" label="Some Form">
        <first-component></first-component>
    </mat-step>
    <mat-step [stepControl]="secondFormGroup" label="Another Form">
        <second-component></second-component>
    </mat-step>
    <mat-step [stepControl]="thirdFormGroup" label="Review">
        <third-component></third-component>
    </mat-step>
</mat-horizontal-stepper>

When I try this, I receive the following error upon hitting the matStepperNext button:

TypeError: Cannot read property 'invalid' of undefined.

Answer 1

Improving on @eliran-eliassy answer and @christian-steinmeyer question.

Parent.Component.ts

  export class ParentComponent implements OnInit {

  isLinear = true;
  companyInfo: FormGroup;

  constructor(private _formBuilder: FormBuilder) {

  }

  ngOnInit() {

    this.companyInfo = this._formBuilder.group({
    });

  }

}

Parent.Component.html

<mat-horizontal-stepper [linear]="isLinear" #stepper>
    <mat-step [stepControl]="companyInfo">
        <form [formGroup]="companyInfo">
            <ng-template matStepLabel>Fill out your name</ng-template>
            <app-company-info></app-company-info>
        </form>
        <div>
            <button mat-button matStepperNext>Next</button>
        </div>
    </mat-step>
</mat-horizontal-stepper>

Child.Component.ts -> this is the sub-form

export class ChildComponent implements OnInit {
  form: FormGroup;
  subForm: FormGroup;
  constructor(
    private ctrlContainer: FormGroupDirective,
    private fb: FormBuilder
  ) {}

  ngOnInit() {
    this.subForm = this.fb.group({
      companyName: [null, [Validators.required]],
      numOfEmployees: [null, [Validators.required]]
    });
    
    this.form = this.ctrlContainer.form;
    this.form.addControl("company", this.subForm);
  }
}

Child.Component.html

<div [formGroup]="subForm">
    <mat-form-field appearance="outline">
        <input matInput placeholder="Your Company Name" formControlName="companyName">
  </mat-form-field>
</div>

See this solution on stackblitz