基于ng-alain定义自己的select组件

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