ng-select：如何 select 具有相同标签但不同对象的多个项目

Question

我正在尝试修补 ng-select 下拉列表中的多个 selected 项目。我没有指定任何 bindValue，因此项目应该按对象绑定（如 https://www.npmjs.com/package/@ng-select/ng-select 中指定）

但是在尝试执行此操作时，项目不会根据对象 select 编辑，而是根据显示的标签进行编辑。同样只有第一个标签得到 selected.

示例：app.component.html

<form [formGroup]="group">
    <div class="form-group" formGroupName="school">
        <ng-select labelForId="school" placeholder="Select school" [items]="schools" formControlName="code"
            bindLabel="displayLabel" multiple="true" groupBy="city">
        </ng-select>
    </div>
</form>

app.component.ts

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
  group: FormGroup;
  schools = [];
  constructor(private fb: FormBuilder) { }

  ngOnInit() {
    this.initSchools();
    const formModel = {
      school: new FormGroup({
        code: new FormControl(null, Validators.required)
      })
    }
    this.group = this.fb.group(formModel);
    this.group.patchValue({
      school: {
        code:
          [
            {
              schoolId: 'SC003',
              displayLabel: 'Test-3 school',
              city: "City1"
            },
            {
              schoolId: 'SC005',
              displayLabel: 'Test-3 school',
              city: "City5"
            }
          ]
      }
    });
  }

  initSchools() {
    this.schools.push(
      {
        schoolId: 'SC001',
        displayLabel: 'Test-1 school',
        city: "City1"
      },
      {
        schoolId: 'SC002',
        displayLabel: 'Test-2 school',
        city: "City2"
      },
      {
        schoolId: 'SC003',
        displayLabel: 'Test-3 school',
        city: "City3"
      },
      {
        schoolId: 'SC004',
        displayLabel: 'Test-4 school',
        city: "City4"
      },
      {
        schoolId: 'SC005',
        displayLabel: 'Test-3 school',
        city: "City5"
      }
    );
  }
}

在上面的例子中只有 item

的对象

    {
      schoolId: 'SC003',
      displayLabel: 'Test-3 school',
      city: "City1"
    },

获得 selected，

而下面的项目没有

    {
      schoolId: 'SC005',
      displayLabel: 'Test-3 school',
      city: "City5"
    }

应该如何使这两个项目都select进入下拉列表（提供独特的对象）。这里有什么遗漏吗？任何其他方式来实现这一目标。

这里有例子运行：https://stackblitz.com/edit/angular-szel64?file=src%2Fapp%2Fapp.component.ts

Answer 1

发现 ng-select 有一个 compareWith 选项，可以让你定义一个函数来比较对象。使用它，您可以绑定对象，它会根据 compareWith 选项提供的功能得到 selected。

以下是我的更改，以防有人遇到同样的问题

app.component.html

<form [formGroup]="group">
    <div class="form-group" formGroupName="school">
        <ng-select labelForId="school" placeholder="Select school" [items]="schools" formControlName="code"
            bindLabel="displayLabel" multiple="true" groupBy="city"
      [compareWith]="compareFunction">
        </ng-select>
    </div>
</form>

app.component.ts

...
  compareFunction(item, selected) {
// any logic to compare the objects and return true or false
    return item.schoolId === selected.schoolId
  }
...

ng-select：如何 select 具有相同标签但不同对象的多个项目

ng-select: how to select multiple items having same label but different object

multi-select

angular-ngselect

dropdown

angular

angular-reactive-forms