node.js - Angular 8 : Dynamically set formControlName in html based on component

Question

在 db 表中，我有“key_name”，它在 API 中成功返回并且运行良好。

我想要做的是将这些字段值设置为 formControlName在 html 和组件中，我使用的是 react 形式，所以我尝试过 formArrayName .

基于更改事件，我正在推送新的 formControl在 categoryArray并将其键分配为 db 字段的值。

这是我的HTML:

<div class="col-md-6">
                            <div formArrayName="categoryArray" *ngFor="let type of types; let k = index">
                                <div [formGroupName]="k">
                                    <div class="form-group">
                                        <label>Select {{ type.cat_name }}</label>
                                        <select class="form-control custom-select" 
                                            (change)="onChangeType($event.target.value)"
                                            formControlName="{{ type.key_name }}" >
                                            <option value="">-- Select --</option>
                                            <option *ngFor="let type of types" [value]="type.category_id">
                                                {{type.cat_name}}
                                            </option>
                                        </select>
                                    </div>
                                </div>
                            </div>
                        </div>

组件.ts:

onChangeCategory(id) {
    if(id) {
      this.artistService.fetchTypeAndSubTypes(id).subscribe(res => {
        if (res.status == 200) {
          this.types = res.data

          this.addInNewCategory(this.types)

        }
      })
    } else {
      this.types = null
      this.subTypes = null
    }
  }

  get category(): FormArray {
    return <FormArray>this.uploadArtWorkForm.controls.categoryArray;
  }

  addInNewCategory(types) {
    let obj = {}

    types.forEach(element => {
      obj[element['key_name']] = [null, [Validators.required]]
    });

    console.log("obj", obj)
    this.category.push(
      this.formBuilder.group(obj)   
    );

  }

我要存档的是，基于第一类别选择，所有第二级别类别将显示为动态 HTML 下拉列表，其子类别列表在下拉列表中。

我得到的错误:

ERROR Error: Cannot find control with path: 'categoryArray -> 1'

ERROR Error: Cannot find control with path: 'categoryArray -> 1 -> metal'

编辑:
设置表单控件名称后，如何设置每个新创建的下拉列表的值？我需要从数据库中获取它。

这是 Stackblitz:
https://stackblitz.com/edit/dyncamic-populating-dropdown

提前致谢

Answer 1

尝试自己修改代码，至少修复了以下错误:

错误错误:找不到路径控制:'categoryArray -> 1'

错误错误:找不到路径控制:'categoryArray -> 1 -> metal'

但是您仍然需要使用我的解决方案进行改进。

Modify your app.component.html as below:

<form [formGroup]="uploadArtWorkForm" (ngSubmit)="addUploadArtWorkForm();">
    <div class="col-md-6">
        <div class="form-group">
            <label>Select Category:</label>
      <select class="form-control custom-select" formControlName="cat_id" [ngClass]="{'is-invalid': uploadArtWorkForm.controls['cat_id'].invalid && (uploadArtWorkForm.controls['cat_id'].dirty || uploadArtWorkForm.controls['cat_id'].touched || isFormSubmitted) }" (change)="onChangeCategory($event, $event.target.value)">
        <option value="">-- Select --</option>
        <option *ngFor="let category of parentCategories" [value] ="category.category_id">
            {{category.cat_name}}
        </option>
      </select>
            <div class="invalid-feedback" *ngIf="uploadArtWorkForm.controls['cat_id'].errors">
                <div *ngIf="uploadArtWorkForm.controls['cat_id'].errors.required">Category is
                    required.</div>
            </div>
        </div>
    </div>
    <div class="col-md-6" formArrayName="categoryArray" *ngIf="uploadArtWorkForm.get('categoryArray')['controls'].length > 0">
        <div  *ngFor="let item of uploadArtWorkForm.get('categoryArray')['controls']; let k = index">
            <div [formGroup]="item">
                <div class="form-group ">
                    <label>Select {{ types[k].cat_name }}</label>
                    <select class="form-control custom-select" [class]="types[k].key_name" (change)="onChangeType($event.target.value)" formControlName="{{ types[k].key_name }}" *ngIf="types[k].cat_name == 'Type'"> 
              <option value="">-- Select --</option>
              <option *ngFor="let type of catTypeValue" [value]="type.category_id">
                  {{type.cat_name}}
              </option>
          </select>
          <select class="form-control custom-select" [class]="types[k].key_name" (change)="onChangeType($event.target.value)" formControlName="{{ types[k].key_name }}" *ngIf="types[k].cat_name == 'Metal'">
              <option value="">-- Select --</option>
              <option *ngFor="let type of catMetalValue" [value]="type.category_id">
                  {{type.cat_name}}
              </option>
          </select>
          <select class="form-control custom-select" [class]="types[k].key_name" (change)="onChangeType($event.target.value)" formControlName="{{ types[k].key_name }}" *ngIf="types[k].cat_name == 'Gems'">
              <option value="">-- Select --</option>
              <option *ngFor="let type of catGemsValue" [value]="type.category_id">
                  {{type.cat_name}}
              </option>
          </select>
                </div>
            </div>
        </div>
    </div>
</form>

and app.component.ts as below:

import { Component } from "@angular/core";
import { FormGroup, FormBuilder, Validators, FormArray, FormControl } from "@angular/forms";

@Component({
  selector: "my-app",
  templateUrl: "./app.component.html",
  styleUrls: ["./app.component.css"]
})
export class AppComponent {
  uploadArtWorkForm: any;
  uploadArtWorkForm1: any;
  isFormSubmitted: boolean = false;

  parentCategories = [
    {"parent_id":0,"cat_name":"Jewelry","category_id":1},
    {"parent_id":0,"cat_name":"Painting","category_id":16},
    {"parent_id":0,"cat_name":"Photograph","category_id":22}];
  types;
  subTypes;

  //below value will be displayed in Select Type dropdown
  catTypeValue = [
    {"parent_id":2,"cat_name":"Anklets","category_id":3,"key_name":"anklets"},
    {"parent_id":2,
    "cat_name":"Body",
    "category_id":4,
    "key_name":"body"},
    {"parent_id":2,"cat_name":"Bracelets","category_id":5,
    "key_name":""},
    {"parent_id":2,
    "cat_name":"Charms","category_id":6,
    "key_name":""},
    {"parent_id":2,"cat_name":"Necklaces","category_id":7,
    "key_name":""},
    {"parent_id":2,"cat_name":"Ornamental","category_id":8,
    "key_name":""},
    {"parent_id":2,
    "cat_name":"Rings & Studs","category_id":9,
    "key_name":""},
    {"parent_id":2,
    "cat_name":"Jewelry Metal","category_id":10,"key_name":""},{"parent_id":2,
    "cat_name":"Yellow Gold","category_id":11,
    "key_name":""},
    {"parent_id":2,
    "cat_name":"White Gold","category_id":12,"key_name":"whitegold"},{"parent_id":2,
    "cat_name":"Silver","category_id":13,"key_name":"silver"}
    ]

  // below values will be displayed in Select Metal dd
  catMetalValue = [
    {"parent_id":14,"cat_name":"White Gold","category_id":24,"key_name":"whitegold"},
    {"parent_id":14,"cat_name":"Yellow Gold","category_id":24,"key_name":"whitegold"},
    ]

  // below values will be displayed in Select Gems dd
  catGemsValue = [
    {"parent_id":15,"cat_name":"Blue Gems","category_id":25,"key_name":"bluegems"}
    ]

  constructor(private formBuilder: FormBuilder) {
    this.uploadArtWorkForm = this.formBuilder.group({
    cat_id: new FormControl('', Validators.required),
    categoryArray: this.formBuilder.array([]),
  });
  }
  ngOnInit() {}
  onChangeType(value, id){
    console.log(value)
// solution to https://stackoverflow.com/questions/61315779/angular-8-not-getting-selected-dropdown-values-in-component-using-reactive-form?noredirect=1&lq=1
  }
  onChangeCategory(event, id) {
    if (id) {
      this.types = [
        {"parent_id":1,
        "cat_name":"Type",
        "category_id":2,
        "key_name":"type"},
        {"parent_id":1,
        "cat_name":"Metal",
        "category_id":14,
        "key_name":"metal"},
        {"parent_id":1,
        "cat_name":"Gems",
        "category_id":15,
        "key_name":"gems"}];
      if(this.uploadArtWorkForm.controls['categoryArray'].length > 0){
        this.uploadArtWorkForm.controls['categoryArray'].controls.length = 0
      }
      this.addInNewCategory(this.types);
    } else {
      this.types = null;
      this.subTypes = null;
    }
  }

  get category(): FormArray {
    return <FormArray>this.uploadArtWorkForm.controls['categoryArray'];
  }

  addInNewCategory(types) {['categoryArray'];
    types.forEach((element, i) => {
      this.category.push(this.formBuilder.group({[element["key_name"]]: new FormControl(element["key_name"])
      }));
    });
  }
}