反应形式 patchValue() 与 ngValue 不起作用

Question

I have one dropdown in reactive forms I have used the whole object as the value( {NAME:'test',CODE:'002'} ) for further processing, its working fine I am able to get selected item in .ts file.In edit mode, I have to bind selected item to drown using patchValue but it's not working.

html

                     <select class="form-group form-control" formControlName="county">
                                <option value="">-Select-</option>
                                <option *ngFor="let item of countyDataset" [ngValue]='item'>{{item.NAME}}
                                </option>
                            </select>

.ts code

bindDataValue(){
    const rec=county{
         CODE: "028"
          NAME: "LOS ALAMOS"
       }
this.form.patchValue(rec);
}

Answer 1

  <h1>Reactive Forms</h1>
    
  <div style="padding: 0 0 20px 20px">
  
    <h3>Value string</h3>
    <form [formGroup]="selectForm">
    <mat-form-field>
      <mat-select name="countryReactiveString" formControlName="selectedCountryControl" placeholder="Country">
        <mat-option *ngFor="let country of countries" [value]="country">{{country?.full}}</mat-option>
      </mat-select>
    </mat-form-field>
    </form>
    {{selectForm.value | json}}
  </div>


import { Component, OnInit } from '@angular/core';
import { FormControl, FormGroup, FormBuilder } from '@angular/forms';


@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.scss' ]
})
export class AppComponent implements OnInit {
  selectForm: FormGroup;
  constructor(private fb: FormBuilder) {}
  
  countries: any = [
    {
      full: "Great Britain",
      short: "GB"
    },
    {
      full: "United States",
      short: "US"
    },
    {
      full: "Canada",
      short: "CA"
    }
  ];
  ngOnInit() {
    this.selectForm = this.fb.group({
      selectedCountryControl: []
    })
    this.selectForm.patchValue({
       selectedCountryControl: this.countries[0]
    })
  }

}

Here is demo it should workhttps://stackblitz.com/edit/angular-material-select-demo-d7edt6