Angular How to add Validator to FormControl after control is created?

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);

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

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

Thanks a bunch.

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

asked Aug 5 '16 at 20:34

melegant

1991211

add a comment |

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);

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

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

Thanks a bunch.

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

asked Aug 5 '16 at 20:34

melegant

1991211

add a comment |

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);

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

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

Thanks a bunch.

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

asked Aug 5 '16 at 20:34

melegant

1991211

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);

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

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

Thanks a bunch.

forms angular

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

asked Aug 5 '16 at 20:34

melegant

1991211

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

asked Aug 5 '16 at 20:34

melegant

1991211

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

edited Feb 14 '18 at 11:40

shammelburg

2,42241829

asked Aug 5 '16 at 20:34

melegant

1991211

asked Aug 5 '16 at 20:34

melegant

1991211

asked Aug 5 '16 at 20:34

melegant

1991211

add a comment |

3 Answers
3

active

oldest

votes

You simply pass the FormControl an array of validators.

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)]);

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

edited Aug 5 '16 at 21:00

answered Aug 5 '16 at 20:47

Delosdos

1,872820

4

ha...sometimes you look at something so long it is best to just step away. THANK YOU!!
– melegant
Aug 6 '16 at 14:43

glad to help :)
– Delosdos
Aug 6 '16 at 14:52

This really solved the problem that I was trying to fix for a long time. Thanks a ton for sharing!
– Devner
May 12 '17 at 5:28

1

Is there a way to remove validation
– Abhijith s.s
Aug 18 '17 at 11:57

4

this.form.controls["firstName"].clearValidators()
– DDD Soft
Sep 6 '17 at 14:56

|
show 4 more comments

To add onto what @Delosdos has posted.

Set a validator for a control in the FormGroup:
this.myForm.controls['controlName'].setValidators([Validators.required])

Remove the validator from the control in the FormGroup:
this.myForm.controls['controlName'].clearValidators()

Update the FormGroup once you have run either of the above lines.
this.myForm.controls['controlName'].updateValueAndValidity()

This is an amazing way to programmatically set your form validation.

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

For me it worked without the last line, I'm pretty sure new versions of Angular update the form validity by themselves now. But thanks for telling us about the updateValueAndValidity method, might come handy one day!
– Nino Filiu
Jul 24 '18 at 9:06

@NinoFiliu updateValueAndValidity is still used to perform the validation, and isn't handled any differently in newer versions of Angular. What happens is setValidators updates the validators, but doesn't run a validation check, and then you use updateValueAndValidity to perform the validation. You must be setting the validators at a point where change detection handles it for you, but you'll find using updateValueAndValidity on the group or control depending what validator you just set crucial - github.com/angular/angular/issues/19622#issuecomment-341547884.
– mtpultz
Aug 9 '18 at 19:44

I'm on Angular 6 and couldn't make it work without the updateValueAndValidity. Thanks @shammelburg !
– Oli Crt
Dec 20 '18 at 16:12

add a comment |

If you are using reactiveFormModule and have formGroup defined like this:

public exampleForm = new FormGroup({

        name: new FormControl('Test name', [Validators.required, Validators.minLength(3)]),

        email: new FormControl('test@example.com', [Validators.required, Validators.maxLength(50)]),

        age: new FormControl(45, [Validators.min(18), Validators.max(65)])

});

than you are able to add a new validator (and keep old ones) to FormControl with this approach:

this.exampleForm.get('age').setValidators([

        Validators.pattern('^[0-9]*$'),

        this.exampleForm.get('age').validator

]);

this.exampleForm.get('email').setValidators([

        Validators.email,

        this.exampleForm.get('email').validator

]);

FormControl.validator returns a compose validator containing all previously defined validators.

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

2

Imo this should be the accepted answer. It demonstrates how to add validators like OP requested, but also shows you how to retain previously set validators; which was the first thing I googled how to do after I read the accepted answer, because I didn't want to overwrite some validators I already had, but still needed to programatically add additional ones. Thank you for this answer @Eduard Void
– Chris
Nov 16 '18 at 20:45

I agree with my predecessor. The question was how to add new validator to control form, not how to replace it.
– Plusce
Dec 5 '18 at 14:57

add a comment |

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

You simply pass the FormControl an array of validators.

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)]);

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

edited Aug 5 '16 at 21:00

answered Aug 5 '16 at 20:47

Delosdos

1,872820

4

ha...sometimes you look at something so long it is best to just step away. THANK YOU!!
– melegant
Aug 6 '16 at 14:43

glad to help :)
– Delosdos
Aug 6 '16 at 14:52

This really solved the problem that I was trying to fix for a long time. Thanks a ton for sharing!
– Devner
May 12 '17 at 5:28

1

Is there a way to remove validation
– Abhijith s.s
Aug 18 '17 at 11:57

4

this.form.controls["firstName"].clearValidators()
– DDD Soft
Sep 6 '17 at 14:56

|
show 4 more comments

You simply pass the FormControl an array of validators.

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)]);

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

edited Aug 5 '16 at 21:00

answered Aug 5 '16 at 20:47

Delosdos

1,872820

4

ha...sometimes you look at something so long it is best to just step away. THANK YOU!!
– melegant
Aug 6 '16 at 14:43

glad to help :)
– Delosdos
Aug 6 '16 at 14:52

This really solved the problem that I was trying to fix for a long time. Thanks a ton for sharing!
– Devner
May 12 '17 at 5:28

1

Is there a way to remove validation
– Abhijith s.s
Aug 18 '17 at 11:57

4

this.form.controls["firstName"].clearValidators()
– DDD Soft
Sep 6 '17 at 14:56

|
show 4 more comments

You simply pass the FormControl an array of validators.

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)]);

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

edited Aug 5 '16 at 21:00

answered Aug 5 '16 at 20:47

Delosdos

1,872820

You simply pass the FormControl an array of validators.

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)]);

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

edited Aug 5 '16 at 21:00

answered Aug 5 '16 at 20:47

Delosdos

1,872820

edited Aug 5 '16 at 21:00

answered Aug 5 '16 at 20:47

Delosdos

1,872820

answered Aug 5 '16 at 20:47

Delosdos

1,872820

answered Aug 5 '16 at 20:47

Delosdos

1,872820

4

ha...sometimes you look at something so long it is best to just step away. THANK YOU!!
– melegant
Aug 6 '16 at 14:43

glad to help :)
– Delosdos
Aug 6 '16 at 14:52

This really solved the problem that I was trying to fix for a long time. Thanks a ton for sharing!
– Devner
May 12 '17 at 5:28

1

Is there a way to remove validation
– Abhijith s.s
Aug 18 '17 at 11:57

4

this.form.controls["firstName"].clearValidators()
– DDD Soft
Sep 6 '17 at 14:56

|
show 4 more comments

4

ha...sometimes you look at something so long it is best to just step away. THANK YOU!!
– melegant
Aug 6 '16 at 14:43

glad to help :)
– Delosdos
Aug 6 '16 at 14:52

This really solved the problem that I was trying to fix for a long time. Thanks a ton for sharing!
– Devner
May 12 '17 at 5:28

1

Is there a way to remove validation
– Abhijith s.s
Aug 18 '17 at 11:57

4

this.form.controls["firstName"].clearValidators()
– DDD Soft
Sep 6 '17 at 14:56

ha...sometimes you look at something so long it is best to just step away. THANK YOU!!
– melegant
Aug 6 '16 at 14:43

glad to help :)
– Delosdos
Aug 6 '16 at 14:52

This really solved the problem that I was trying to fix for a long time. Thanks a ton for sharing!
– Devner
May 12 '17 at 5:28

Is there a way to remove validation
– Abhijith s.s
Aug 18 '17 at 11:57

this.form.controls["firstName"].clearValidators()
– DDD Soft
Sep 6 '17 at 14:56

|
show 4 more comments

To add onto what @Delosdos has posted.

Set a validator for a control in the FormGroup:
this.myForm.controls['controlName'].setValidators([Validators.required])

Remove the validator from the control in the FormGroup:
this.myForm.controls['controlName'].clearValidators()

Update the FormGroup once you have run either of the above lines.
this.myForm.controls['controlName'].updateValueAndValidity()

This is an amazing way to programmatically set your form validation.

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

For me it worked without the last line, I'm pretty sure new versions of Angular update the form validity by themselves now. But thanks for telling us about the updateValueAndValidity method, might come handy one day!
– Nino Filiu
Jul 24 '18 at 9:06

@NinoFiliu updateValueAndValidity is still used to perform the validation, and isn't handled any differently in newer versions of Angular. What happens is setValidators updates the validators, but doesn't run a validation check, and then you use updateValueAndValidity to perform the validation. You must be setting the validators at a point where change detection handles it for you, but you'll find using updateValueAndValidity on the group or control depending what validator you just set crucial - github.com/angular/angular/issues/19622#issuecomment-341547884.
– mtpultz
Aug 9 '18 at 19:44

I'm on Angular 6 and couldn't make it work without the updateValueAndValidity. Thanks @shammelburg !
– Oli Crt
Dec 20 '18 at 16:12

add a comment |

To add onto what @Delosdos has posted.

Set a validator for a control in the FormGroup:
this.myForm.controls['controlName'].setValidators([Validators.required])

Remove the validator from the control in the FormGroup:
this.myForm.controls['controlName'].clearValidators()

Update the FormGroup once you have run either of the above lines.
this.myForm.controls['controlName'].updateValueAndValidity()

This is an amazing way to programmatically set your form validation.

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

For me it worked without the last line, I'm pretty sure new versions of Angular update the form validity by themselves now. But thanks for telling us about the updateValueAndValidity method, might come handy one day!
– Nino Filiu
Jul 24 '18 at 9:06

@NinoFiliu updateValueAndValidity is still used to perform the validation, and isn't handled any differently in newer versions of Angular. What happens is setValidators updates the validators, but doesn't run a validation check, and then you use updateValueAndValidity to perform the validation. You must be setting the validators at a point where change detection handles it for you, but you'll find using updateValueAndValidity on the group or control depending what validator you just set crucial - github.com/angular/angular/issues/19622#issuecomment-341547884.
– mtpultz
Aug 9 '18 at 19:44

I'm on Angular 6 and couldn't make it work without the updateValueAndValidity. Thanks @shammelburg !
– Oli Crt
Dec 20 '18 at 16:12

add a comment |

To add onto what @Delosdos has posted.

Set a validator for a control in the FormGroup:
this.myForm.controls['controlName'].setValidators([Validators.required])

Remove the validator from the control in the FormGroup:
this.myForm.controls['controlName'].clearValidators()

Update the FormGroup once you have run either of the above lines.
this.myForm.controls['controlName'].updateValueAndValidity()

This is an amazing way to programmatically set your form validation.

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

To add onto what @Delosdos has posted.

Set a validator for a control in the FormGroup:
this.myForm.controls['controlName'].setValidators([Validators.required])

Remove the validator from the control in the FormGroup:
this.myForm.controls['controlName'].clearValidators()

Update the FormGroup once you have run either of the above lines.
this.myForm.controls['controlName'].updateValueAndValidity()

This is an amazing way to programmatically set your form validation.

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

answered Dec 11 '17 at 11:21

shammelburg

2,42241829

For me it worked without the last line, I'm pretty sure new versions of Angular update the form validity by themselves now. But thanks for telling us about the updateValueAndValidity method, might come handy one day!
– Nino Filiu
Jul 24 '18 at 9:06

@NinoFiliu updateValueAndValidity is still used to perform the validation, and isn't handled any differently in newer versions of Angular. What happens is setValidators updates the validators, but doesn't run a validation check, and then you use updateValueAndValidity to perform the validation. You must be setting the validators at a point where change detection handles it for you, but you'll find using updateValueAndValidity on the group or control depending what validator you just set crucial - github.com/angular/angular/issues/19622#issuecomment-341547884.
– mtpultz
Aug 9 '18 at 19:44

I'm on Angular 6 and couldn't make it work without the updateValueAndValidity. Thanks @shammelburg !
– Oli Crt
Dec 20 '18 at 16:12

add a comment |

For me it worked without the last line, I'm pretty sure new versions of Angular update the form validity by themselves now. But thanks for telling us about the updateValueAndValidity method, might come handy one day!
– Nino Filiu
Jul 24 '18 at 9:06

@NinoFiliu updateValueAndValidity is still used to perform the validation, and isn't handled any differently in newer versions of Angular. What happens is setValidators updates the validators, but doesn't run a validation check, and then you use updateValueAndValidity to perform the validation. You must be setting the validators at a point where change detection handles it for you, but you'll find using updateValueAndValidity on the group or control depending what validator you just set crucial - github.com/angular/angular/issues/19622#issuecomment-341547884.
– mtpultz
Aug 9 '18 at 19:44

I'm on Angular 6 and couldn't make it work without the updateValueAndValidity. Thanks @shammelburg !
– Oli Crt
Dec 20 '18 at 16:12

For me it worked without the last line, I'm pretty sure new versions of Angular update the form validity by themselves now. But thanks for telling us about the updateValueAndValidity method, might come handy one day!
– Nino Filiu
Jul 24 '18 at 9:06

@NinoFiliu updateValueAndValidity is still used to perform the validation, and isn't handled any differently in newer versions of Angular. What happens is setValidators updates the validators, but doesn't run a validation check, and then you use updateValueAndValidity to perform the validation. You must be setting the validators at a point where change detection handles it for you, but you'll find using updateValueAndValidity on the group or control depending what validator you just set crucial - github.com/angular/angular/issues/19622#issuecomment-341547884.
– mtpultz
Aug 9 '18 at 19:44

I'm on Angular 6 and couldn't make it work without the updateValueAndValidity. Thanks @shammelburg !
– Oli Crt
Dec 20 '18 at 16:12

add a comment |

If you are using reactiveFormModule and have formGroup defined like this:

public exampleForm = new FormGroup({

        name: new FormControl('Test name', [Validators.required, Validators.minLength(3)]),

        email: new FormControl('test@example.com', [Validators.required, Validators.maxLength(50)]),

        age: new FormControl(45, [Validators.min(18), Validators.max(65)])

});

than you are able to add a new validator (and keep old ones) to FormControl with this approach:

this.exampleForm.get('age').setValidators([

        Validators.pattern('^[0-9]*$'),

        this.exampleForm.get('age').validator

]);

this.exampleForm.get('email').setValidators([

        Validators.email,

        this.exampleForm.get('email').validator

]);

FormControl.validator returns a compose validator containing all previously defined validators.

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

2

Imo this should be the accepted answer. It demonstrates how to add validators like OP requested, but also shows you how to retain previously set validators; which was the first thing I googled how to do after I read the accepted answer, because I didn't want to overwrite some validators I already had, but still needed to programatically add additional ones. Thank you for this answer @Eduard Void
– Chris
Nov 16 '18 at 20:45

I agree with my predecessor. The question was how to add new validator to control form, not how to replace it.
– Plusce
Dec 5 '18 at 14:57

add a comment |

If you are using reactiveFormModule and have formGroup defined like this:

public exampleForm = new FormGroup({

        name: new FormControl('Test name', [Validators.required, Validators.minLength(3)]),

        email: new FormControl('test@example.com', [Validators.required, Validators.maxLength(50)]),

        age: new FormControl(45, [Validators.min(18), Validators.max(65)])

});

than you are able to add a new validator (and keep old ones) to FormControl with this approach:

this.exampleForm.get('age').setValidators([

        Validators.pattern('^[0-9]*$'),

        this.exampleForm.get('age').validator

]);

this.exampleForm.get('email').setValidators([

        Validators.email,

        this.exampleForm.get('email').validator

]);

FormControl.validator returns a compose validator containing all previously defined validators.

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

2

Imo this should be the accepted answer. It demonstrates how to add validators like OP requested, but also shows you how to retain previously set validators; which was the first thing I googled how to do after I read the accepted answer, because I didn't want to overwrite some validators I already had, but still needed to programatically add additional ones. Thank you for this answer @Eduard Void
– Chris
Nov 16 '18 at 20:45

I agree with my predecessor. The question was how to add new validator to control form, not how to replace it.
– Plusce
Dec 5 '18 at 14:57

add a comment |

If you are using reactiveFormModule and have formGroup defined like this:

public exampleForm = new FormGroup({

        name: new FormControl('Test name', [Validators.required, Validators.minLength(3)]),

        email: new FormControl('test@example.com', [Validators.required, Validators.maxLength(50)]),

        age: new FormControl(45, [Validators.min(18), Validators.max(65)])

});

than you are able to add a new validator (and keep old ones) to FormControl with this approach:

this.exampleForm.get('age').setValidators([

        Validators.pattern('^[0-9]*$'),

        this.exampleForm.get('age').validator

]);

this.exampleForm.get('email').setValidators([

        Validators.email,

        this.exampleForm.get('email').validator

]);

FormControl.validator returns a compose validator containing all previously defined validators.

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

If you are using reactiveFormModule and have formGroup defined like this:

public exampleForm = new FormGroup({

        name: new FormControl('Test name', [Validators.required, Validators.minLength(3)]),

        email: new FormControl('test@example.com', [Validators.required, Validators.maxLength(50)]),

        age: new FormControl(45, [Validators.min(18), Validators.max(65)])

});

than you are able to add a new validator (and keep old ones) to FormControl with this approach:

this.exampleForm.get('age').setValidators([

        Validators.pattern('^[0-9]*$'),

        this.exampleForm.get('age').validator

]);

this.exampleForm.get('email').setValidators([

        Validators.email,

        this.exampleForm.get('email').validator

]);

FormControl.validator returns a compose validator containing all previously defined validators.

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

answered Nov 13 '18 at 8:32

Eduard Void

1,30288

2

Imo this should be the accepted answer. It demonstrates how to add validators like OP requested, but also shows you how to retain previously set validators; which was the first thing I googled how to do after I read the accepted answer, because I didn't want to overwrite some validators I already had, but still needed to programatically add additional ones. Thank you for this answer @Eduard Void
– Chris
Nov 16 '18 at 20:45

I agree with my predecessor. The question was how to add new validator to control form, not how to replace it.
– Plusce
Dec 5 '18 at 14:57

add a comment |

2

Imo this should be the accepted answer. It demonstrates how to add validators like OP requested, but also shows you how to retain previously set validators; which was the first thing I googled how to do after I read the accepted answer, because I didn't want to overwrite some validators I already had, but still needed to programatically add additional ones. Thank you for this answer @Eduard Void
– Chris
Nov 16 '18 at 20:45

I agree with my predecessor. The question was how to add new validator to control form, not how to replace it.
– Plusce
Dec 5 '18 at 14:57

Imo this should be the accepted answer. It demonstrates how to add validators like OP requested, but also shows you how to retain previously set validators; which was the first thing I googled how to do after I read the accepted answer, because I didn't want to overwrite some validators I already had, but still needed to programatically add additional ones. Thank you for this answer @Eduard Void
– Chris
Nov 16 '18 at 20:45

I agree with my predecessor. The question was how to add new validator to control form, not how to replace it.
– Plusce
Dec 5 '18 at 14:57

add a comment |

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