使用 angular 从选项下拉列表中过滤/搜索

Question

我有带有复选框和下拉列表选项的多选下拉菜单。 我想为下拉选项实现运行时/动态过滤搜索。 我能够实现过滤搜索，但不能在运行时实现。

this.options = [{ value: "Small", selected: false },
        { value: "Medium", selected: false},
        { value: "Large", selected: false }]

filterUsers() {
        let filterUsers= this.options.filter(item => item.value === this.selectedUser);
        if (filterUsers.length > 0) {
            this.options = filterUsers;
        }
 }    
        console.log(filterUsers);
    }

HTML

<input type = "text" [(ngModel)]="selectedUser" (input) = "filterUsers()">

如何动态实现过滤搜索？

Answer 1

像这样尝试：

  options = [
    { value: "Small", selected: false },
    { value: "Medium", selected: false },
    { value: "Large", selected: false }
  ];

  selectedUser: any;
  filterdOptions = [];
  filterUsers() {
    this.filterdOptions = this.options.filter(
      item => item.value.toLowerCase().includes(this.selectedUser.toLowerCase())
    );
    console.log(this.filterdOptions);
  }

演示

如果您开始输入sm ，则过滤选项将显示值为Small的对象

Answer 2

尝试这个：

options = [
{ value: "Small", selected: false },
{ value: "Medium", selected: false },
{ value: "Large", selected: false }
 ];

 selectedUser: any;
 filterdOptions = [];
 filterUsers() {
 this.filterdOptions = this.options.filter((item:any)=>{
  return  item.value.toLowerCase()=== this.selectedUser.toLowerCase()
 });
console.log(this.filterdOptions);
}

Answer 3

如果您希望这是动态的（即基于更改的值或输入搜索词），您可以将管道用于此类任务。 见https://angular.io/guide/pipes

要在您的情况下实现，请首先创建此管道（并在您的应用程序模块声明中引用）；

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
    name: 'searchOptions'
})
export class SearchOptionsPipe implements PipeTransform {
    transform(items: any[], filter: string): any {
        if (!items || !filter) {
            return items;
        }

        // This will search and match any option.value that contains the search term
        return items.filter(item => item.value.toLowerCase().indexOf(filter.toLowerCase()) !== -1);
    }
}

然后在你的 component.html （无论你在哪里 *ngFor'ing 你的选项）；

<mat-option 
    *ngFor="let option of options | searchOptions:searchTerm"
    [value]="option.value"  ... >{{ option.title }}</mat-option>

最后在你的 component.ts 中你可以配置选项和搜索；

options = [
             {value: 'apple', title: 'Yummy Apple'}, 
             {value: 'orange', title: 'Juicy Orange'}, 
             {value: 'pineapple', title: 'Sweet Pineapple'}
          ];

searchTerm = 'apple'; // Would show the 1st and 3rd item