【Angular】——无限级下拉列表框

  前言

  前段时间换了新框架，将前后端分离，对Angular2有点感兴趣，所以参与一起封装组件。在小5的帮助下，学会了

好多东西，这里总结下封装的无限级下拉列表框。

 dropdownlist.ts

 

import { Component,OnInit,Output,EventEmitter,Input } from '@angular/core';
import { URLSearchParams }                            from '@angular/http';

import {DataService}                                  from "./dataservice";

@Component({
    selector:'dropdownlist',
    templateUrl:'./dropdownlist.component.html',  
    styleUrls:['./dropdownlist.component.css'],    
})

export class DropDownListComponent{  
    @Input() urls:String[][] = new Array();//保存传递过来的url
    datas:String[][] = new Array(); //保存查询结果
    @Input() titles:String[][] = new Array();//保存提示语句
    condition:string = "";//查询条件
    index:number = 0;

    constructor(public dataService : DataService ){}

    ngOnInit(){        
        this.getData(this.condition,this.index);           
    }
    getData(condition : string,index : number ):void{              
        var condition = (condition == "" ? "" : condition);               
        if(index < this.urls.length){         
            let url = this.urls[index].toString() + condition;  
            this.dataService.getData(url).then( res=>
            {             
                this.datas[index] = res;                               
            });        
        }       
    }
    dataChange(condition:string,i:number){               
        this.getData(condition,i+1);
    }

}

  dropdownlist.component.html

 

<div>
  <select name="data" class="combobox form-control"  *ngFor="let url of urls,let i = index" (change)="dataChange($event.target.value,i)">
    <option value="-1">--{{titles[i]}}--</option>
    <option *ngFor="let item of datas[i]" value="{{item.id}}" >{{item.name}}</option>
  </select>
</div>

  组件应用

  上边就是我封装无限级下拉列表框所用的关键代码，将上述的组件发布之后，将组件down下来并引用，下拉列表

框的组件就可以投入使用了。代码部分：

  app.module.ts代码：

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';
import { DropDownListModule } from 'ng-itoo-dropdownlist';

import { AppComponent } from './app.component';


@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule,   
    DropDownListModule 
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

  app.component.html代码：

<dropdownlist [titles]='titles' [urls]='urls' ></dropdownlist >

  app.component.ts代码：

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  titles = ['请选择省份','请选择市','请选择区县'];
  urls=['http://localhost:8081/rest/item/countries','http://localhost:8081/rest/item/provinces/','http://localhost:8081/rest/item/cities/'];
  // titles = ['请选择省份'];
  // urls=['http://localhost:8081/rest/item/countries'];
}

  页面效果：