Angular 2动态设置输入最大长度 [英] Angular 2 set input max length dynamically

问题描述

我想从服务获取输入的最大长度（执行http调用以获取值）。

I would like to get the max length of an input from a service (do an http call to get the value).

有没有办法做到这一点只调用一次服务？

Is there any way to do it with calling the service only once?

<input type="text" [attr.maxLength]="getMaxLength()/>

谢谢

推荐答案

将maxLength属性值设置为类属性，该值在contructor或ngOnInit中设置将使其停止再调用该服务

Setting maxLength attribute value to a class property which value is set in contructor or ngOnInit will make it stop calling the service anymore

HTML：

<input type="text" [maxLength]="maxLength"/>

打字稿

  maxLength: number;
  .....
  constructor(private myService: MyService){
    this.maxLength =  this.myService.getMaxLength();
  }

DEMO

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