Angular 2 FormGroup 添加验证器动态

问题描述

我正在尝试将验证器添加到 FormContol 动态中(不是在初始化时)，但它不起作用....

代码:

this.formGroup.controls["firstName"].validator = Validators.Required;

有人做过吗?

解决方案

试试这个，应该可以

this.formGroup.controls["firstName"].setValidators(Validators.required);

对于多个验证器

this.formGroup.controls["firstName"].setValidators([Validators.required, Validators.minLength(2)]);

但是这样做会覆盖初始化期间提供的任何验证器

编辑:

为了立即反映新添加的Validators表单控件，我们必须在设置validators后调用this.formGroup.controls["firstName"].updateValueAndValidity();动态.

this.formGroup.controls["firstName"].setValidators(Validators.required);this.formGroup.controls["firstName"].updateValueAndValidity();

DEMO 相同>

* 注意 *

updateValueAndValidity() 将触发 valueChanges 事件，即使该值并未真正改变(如果您从 valueChanges 订阅中调用它，则可能导致无限循环).您可以通过使用可选参数对象来防止这种情况:{ onlySelf: true, emitEvent: false}

i'm tring to add validator to FormContol dynamic (not on initialization) and it's not work....

the code:

this.formGroup.controls["firstName"].validator = Validators.Required;

Did anyone do it?

解决方案

Try this, it should work

this.formGroup.controls["firstName"].setValidators(Validators.required);

For multiple validators

this.formGroup.controls["firstName"].setValidators([Validators.required, Validators.minLength(2)]);

But doing so will override any validators that are provided during initialization

EDIT :

To reflect the form controls with newly added Validators immediately, we have to call this.formGroup.controls["firstName"].updateValueAndValidity(); after setting validators dynamically.

this.formGroup.controls["firstName"].setValidators(Validators.required);
this.formGroup.controls["firstName"].updateValueAndValidity();

DEMO for the same

* NOTE *

updateValueAndValidity() will trigger a valueChanges event even if the value didn't really change (potentially resulting in an infinite loop, if you're calling it from within a valueChanges subscription). You can prevent that by using the optional parameter object: { onlySelf: true, emitEvent: false}

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