angular基于ng-alain定义自己的select组件示例

1、首先是my-select2.component.html页面,这里是在ng-alain的select基础上根据业务需求添加新的功能;代码如下：

<nz-select #select style="width:100%;" [(ngModel)]="selectedOption" [nzPlaceHolder]="myPlaceHolder" nzAllowClear [nzShowSearch]="true" [nzNotFoundContent]="'无匹配'">
  <nz-option
    *ngFor="let option of options"
    [nzLabel]="option.label"
    [nzValue]="option"
    [nzDisabled]="option.disabled">
  </nz-option>
</nz-select>

2、再者是my-select2.component.ts页面,代码里面有注释;代码如下：

import { ControlValueAccessor } from '@angular/forms/src/directives';
import { Component, forwardRef, Input,OnInit,ElementRef,Output,EventEmitter} from '@angular/core';
import { NG_VALUE_ACCESSOR } from '@angular/forms';
import { Router, NavigationEnd } from '@angular/router';
import { FormGroup, FormBuilder, Validators } from '@angular/forms';
import { SelectService } from './my-select2.service';
declare var $: any;
@Component({
 selector: 'nz-select2',
 templateUrl: './my-select2.component.html',
 providers: [ 
     {
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => NzSelect2Component),//注入表单控件
      multi: true
     }]
})
export class NzSelect2Component implements OnInit{
  constructor(private selectService:SelectService) { 
  }
 innerValue: any = ''; 
 //监听绑定的值，与外岑的ngModel相互绑定
 set selectedOption(val:any){
   if (val !== this.innerValue) {
      this.innerValue = val;
      this.onChangeCallback(val.value);
      this.dataBack.emit(val.value); // 事件
    }
 }
 get selectedOption():any{
    return this.innerValue;
 }
 options = [];//接收select的数组
  _dataSource:any;//接收本地的自定义数组或者请求返回的数组
 @Input()
 url:any;//请求的url
 @Input()
 myPlaceHolder:any;//自定义的PlaceHolder
 @Input()
 //下拉框的数据格式
  fieldKey:any = {
    text: 'text',
     value: 'value'
  };
 @Input()
  set dataSource(val: any) {
    this._dataSource = val;
    if ($.isArray(this._dataSource)) {   
    this.options=this._dataTransform(this._dataSource);//如果是本地数组或直接请求的数组直接复制
    }
  }
  get dataSource(): any {
    return this._dataSource;
  }
 @Output() dataBack = new EventEmitter<any>();
 registerOnChange(fn: (value: any) => void) { 
   this.onChangeCallback = fn;
 }
 registerOnTouched(fn: any) {
   this.onTouchedCallback = fn;
 }
  writeValue(value: string) {

  }
 onChangeCallback = (value: any) => {};
 onTouchedCallback = (value: any) => {};
 ngOnInit() {
     //如果url存在则直接请求
    if(this.url){
      this.selectService.getValue(this.url).subscribe(data => { 
        data = data.rows || data.data;    
        this.options=this._dataTransform(data);
      });
    }   
 }
 //转换下拉框下的字段
  _dataTransform(data: Array<any>){
    let _data = [];
    for (let i = 0; i < data.length; i++) {
     _data[i] = {};
     _data[i].label = data[i][this.fieldKey.text];
     _data[i].value = data[i][this.fieldKey.value];
    }
    return _data;
 }
}

3、然后是my-select2.service.ts页面,这里主要是请求后台接口返回的下拉数组，url为父组件传过来的链接,代码如下：

import { Injectable } from '@angular/core';
import { Headers, Http, URLSearchParams,RequestOptions } from '@angular/http';
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import 'rxjs/add/operator/toPromise';
// import { environment } from '../../environments/environment';
@Injectable()
export class SelectService {
  constructor(private http: HttpClient) {}
  getValue(url: any):any{
    return this.http
      .get(url);
   
  }
}

4、然后是myselect.module.ts页面,这里，使用该组件的前提是要引入 import { NzSelectModule } from 'ng-zorro-antd',代码如下：

import { NgModule, ModuleWithProviders }    from '@angular/core';
import { CommonModule }  from '@angular/common';
import { FormsModule,ReactiveFormsModule } from '@angular/forms';
import { NzSelect2Component } from './my-select2.component';
import { SelectService } from './my-select2.service';
import { NzSelectModule } from 'ng-zorro-antd';
@NgModule({
  imports: [
    CommonModule,
    FormsModule,
    NzSelectModule,
    ReactiveFormsModule
  ],
  exports:[
    NzSelect2Component
  ],
  declarations: [
    NzSelect2Component
  ],
  providers: [
     SelectService
  ]
}) 

export class MySelectModule {
  constructor() {

  }
}

5、使用方法,在你需要的模块引入：MySelectModule

import { MySelectModule } from 'bizapp/base/components/myselect/myselect.module';

6、如何调用：url为请求后台的接口，fieldKey为数组的格式，这里可以根据后台返回来的格式定义这里的字段，如：后台返回格式为[{dmsm1:5,dmz:5}]则fieldKey的定义如下，myPlaceHolder为初始化时显示的内容，如果是本地数组，则只需要加上[dataSource]="peer"，这里的peer为本地数组

<nz-select2 [url]="'analysis/api/data/code/list/030107'" [(ngModel)]="search2.hpzl" [fieldKey]="{text:'dmsm1',value:'dmz'}" [myPlaceHolder]="'号牌种类'"></nz-select2>

7、总结：通过这个组件，我们只需要修改url和fieldKey就可以在任意模块引入然后使用，减少代码的使用，方便维护

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