在Angular中，创建控件后如何将Validator添加到FormControl? [英] In Angular, how to add Validator to FormControl after control is created?

问题描述

我们有一个具有动态构建表单的组件.添加带有验证器的控件的代码可能如下所示:

We have a component that has a dynamically built form. The code to add a control with validators might look like this:

var c = new FormControl('', Validators.required);

但是假设我想稍后添加第二个验证器.我们怎样才能做到这一点?我们在网上找不到任何关于此的文档.我确实发现在表单控件中有 setValidators

But let's say that I want to add 2nd Validator later. How can we accomplish this? We cannot find any documentation on this online. I did find though in the form controls there is setValidators

this.form.controls["firstName"].setValidators 

但不清楚如何添加新的或自定义的验证器.

but it is not clear how to add a new or custom validator.

推荐答案

您只需向 FormControl 传递一组验证器即可.

You simply pass the FormControl an array of validators.

以下示例展示了如何向现有 FormControl 添加验证器:

Here's an example showing how you can add validators to an existing FormControl:

this.form.controls["firstName"].setValidators([Validators.minLength(1), Validators.maxLength(30)]);

注意，这将重置您在创建 FormControl 时添加的任何现有验证器.

Note, this will reset any existing validators you added when you created the FormControl.

Angular 12 更新

从 Angular 12 开始，如果您想在不删除现有验证器的情况下向表单添加新的验证器，可以使用 addValidator:

Since Angular 12, if you want to add new validators to the form without removing the existing validators, you can use addValidator:

this.form.controls["firstName"].addValidators([Validators.minLength(1), Validators.maxLength(30)]);

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