Why validation is not working? - forms

Question

corporate.html
<form #f="ngForm" name="corporateProfileForm" ng-submit="corporateFrmSave(objDS, objDSCurrency)" novalidate="">
<div class="row form-group">
<div class="col-md-12" >
<input type="text" *ngIf="formData" [(ngModel)]="formData.Corporate_Id" id="corpid" title="Corporate ID" tab-index="1" name="corpid" maxlength="20" #corpid="ngModel" required/>
<label for="corp"><b>Corporate ID</b></label>
<div *ngIf="corpid.invalid && (corpid.dirty || corpid.touched)" class="alert alert-danger">
<div *ngIf="corpid.errors.required">
Name is required.
</div>
<div *ngIf="ncorpidame.errors.minlength">
Name must be at least 4 characters long.
</div>
<div *ngIf="corpid.errors.forbiddenName">
Name cannot be Bob.
</div>
</div>
</div>
</div>
</form>
Iam getting error message as
ERROR TypeError: Cannot read property 'invalid' of undefined

Answer 1

Make sure you define your variable with this structure:
TS file
export class ContactComponent implements OnInit {
myform: any;
corpid: FormControl;
constructor() {
}
ngOnInit() {
this.createFormControls();
this.createForm();
}
createFormControls() {
this.corpid= new FormControl('', Validators.required);
}
createForm() {
this.myform = new FormGroup({
corpid: this.corpid,
});
}
HTML file
<div class="md-form form-sm form-group"
[ngClass]="{
'invalid': corpid.invalid && (corpid.dirty || corpid.touched),
'valid': corpid.valid && (corpid.dirty || corpid.touched)
}">
<i class="fa fa-user prefix"></i>
<input
type="text" id="corpid" class="form-control"
required
[formControlName]="'corpid'">
<label for="corpid" class="">Your corpid</label>
</div>
<div class="form-control-feedback"
*ngIf="corpid.errors && (corpid.dirty || corpid.touched)">
<p *ngIf="corpid.errors.required">corpid is required</p>
</div>
It's hard to tell because issue is not in your HTML snipped but in .ts file.
I hope my Code will be helpfull

Answer 2

The issue is with the *ngIf, so when that condition is checked, Angular renders the rest of the template, and while the small fraction of time while *ngIf is being evaluated, your template reference variable corpid does not exist, so it will throw an error when trying to check the validation intially.
Wrap the input field with the validation div's inside the *ngIf instead of applying it only on the input field.
<div class="row form-group" *ngIf="formData">
<input [(ngModel)]="formData.Corporate_Id" id="corpid" ... >
<!-- more code here... -->
</div>
DEMO