How to pass reactive form data between child to parent components with out using services

问题

We would like to consume child reactive form data from parent when we click on parent button. Currently we are using viewchild for getting the child cpomponent reference. We are getting all static data but not the form filled data.......................................................................................................

parent.component.ts
@ViewChild(DetailsComponent) childrenComponent: childrenComponent;

save(){
let model=this.childrenComponent.buildDetailsModel();
/*here api to save model*/
}
children.component.ts
buildDetailsModel(): Details {
var a = {
  reportedToId: this.detailsForm.get('reportedTo').value,
  reportedOn: this.detailsForm.get('reportedTime').value,
  identifiedById: this.detailsForm.get('identifiedBy').value,
  identifiedOn: this.detailsForm.get('dateAndTimeIdentified').value,
  locationTypeId: this.detailsForm.get('locationType').value,
  addressId: this.detailsForm.get('locationAddress').value,
  AddressLine: this.detailsForm.get('locationOfAddress').value,
  description: this.detailsForm.get('description').value,
  PeopleExposed: this.dataSource
  };
  return a;
}

parent.html 
<child></child>

child.html
<form [formGroup]="detailsForm">
  <div fxLayout="column wrap" fxLayoutGap="12px">

    <div fxLayout="column" fxLayout.lt-sm="column" fxLayout.lt-md="column" 
   fxLayoutGap="24px">

      <div fxFlex="row" fxLayoutGap="24px" fxLayout.lt-md="column">
        <div fxFlex="column">
          <mat-form-field>
            <mat-label>Reported To</mat-label>
            <mat-select matInput formControlName="reportedTo">
              <mat-option value="Test 1">Test 1</mat-option>
              <mat-option value="Test 2">Test 1</mat-option>
            </mat-select>
          </mat-form-field>


          <mat-form-field>
            <input matInput [matDatepicker]="reportedTime" placeholder="Date 
          and time reported" date="true" time="true" 
          formControlName="reportedTime">
            <mat-datepicker-toggle matSuffix [for]="reportedTime"></mat- 
           datepicker-toggle>
            <mat-datepicker #reportedTime></mat-datepicker>
          </mat-form-field>

          <mat-form-field>
            <mat-label>Identified by</mat-label>
            <mat-select matInput formControlName="identifiedBy">
              <mat-option value="Test 1">Test 1</mat-option>
              <mat-option value="Test 2">Test 1</mat-option>
            </mat-select>
          </mat-form-field>
        </div>

回答1:

Wrap your child form Inside form element so that you can submit your child form from parent, Then Inject FormGroupDirective in child component to get ref of parent form

<form (ngSubmit)="save()" [formGroup]="detailsForm"> 
    <app-child></app-child>
    <button type="button">Save</button>
 </form>

Then use controlContainer to provide the existing FormGroupDirective in child component

childcomponent.ts

  form;
  constructor(private fb: FormBuilder, @Host() private parentFor: FormGroupDirective) { }

  ngOnInit() {
    this.form = this.parentFor.form;
    //Add FormControl as per your need
    this.form.addControl('child', this.fb.group({
      name: "",
      email: ""
    }))

  }

child.component.html

<form formGroupName="child">
  <input formControlName="name">
  <input formControlName="email">
</form>

Example:https://stackblitz.com/edit/angular-xusdev

回答2:

If use a "referenceVariable" you has access to all the public variables and function of the "child"

<button (click)="click(mychild)"></button>
<child #mychild></child>

click(mychild.any)
{
   console.log(mychild.detailsForm);
}

Anyway, I think you want a child that belong to a Form. For this you can use viewProviders in child

viewProviders: [
    {
      provide: ControlContainer,
      useExisting: FormGroupDirective
    }
  ]

As this link show

来源：https://stackoverflow.com/questions/53946907/how-to-pass-reactive-form-data-between-child-to-parent-components-with-out-using