Problem statement :
Parent component having <form>
tag and some <input>
tags inside it, and child component also have some <input>
tags, parent component has one <submit>
and we are validating form fields on submit the form.
How to validate the child component <input>
fields from parent component on submit
the form ?
Requirement :
If a parent component has a form containing child components with input
components in their template, then these input
components should be validate on click if submit from the parent component.
Findings :
There are lot of posts in SO having same problem statement but did not find any suitable solution.All the below posts validate the whole form but my requirement is to validate each field in child component.
We can achieve it using template driven
technique as well. Find below the steps :
From parent component to child component we have to pass submit button event.
<button type="button" (click)="enterForm(parentForm)">Submit</button>
Here, parentForm
is the form reference.
call child component method using @ViewChild decorator from parent to pass submit button event
on click of submit.
@ViewChild('validateChildComponentForm') private ChildComponent: ChildComponent;
Pass the reference of child form using @ViewChild decorator into the child component.
@ViewChild('smartyStreetForm') form;
enterForm(parentForm) {
this.submitted = true;
this.ChildComponent.validateChildForm(this.submitted);
if(!parentForm.valid || !this.childFormValidCheck) {
return;
} else {
// success code comes here.
}
}
Now in child component method we will check that if parent form is submitted and child component form is valid then emit true otherwise false into the parent component. we will use @Output decorator to emit the isChildFormValid
value into the parent component.
@Output() isChildFormValid: EventEmitter<any> = new EventEmitter<any>();
public validateChildForm(data: any) {
if (data === true) {
if(this.form.valid === true) {
this.isChildFormValid.emit(true);
} else {
this.isChildFormValid.emit(false);
}
}
}
Now in parent component we will get the isChildFormValid value.
private isChildFormValid(formValid: any) {
this.childFormValidCheck = formValid;
}
Pictorial representation :