Validator
An interface implemented by classes that perform synchronous validation.
interface Validator {
validate(control: AbstractControl): ValidationErrors | null
registerOnValidatorChange(fn: () => void)?: void
}
Child interfaces
Class implementations
Methods
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Method that performs synchronous validation against the provided control. |
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Parameters
Returns
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Registers a callback function to call when the validator inputs change. |
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Parameters
Returns
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Usage notes
Provide a custom validator
The following example implements the Validator interface to create a
validator directive with a custom error key.
@Directive({
selector: '[customValidator]',
providers: [{provide: NG_VALIDATORS, useExisting: CustomValidatorDirective, multi: true}]
})
class CustomValidatorDirective implements Validator {
validate(control: AbstractControl): ValidationErrors|null {
return {'custom': true};
}
}