The state of an Angular 4 form updates after the second keystroke in an input field

I want to save the user's data every time they make a change in the input control but not when the page loads. Below is my code:

HTML page:

<form  [formGroup]="singleTextForm">
  <mat-form-field class="text-box-width">
    <input matInput placeholder=""  formControlName="AnswersResponses" [ngModel]="AnswersResponses?.answerText" (ngModelChange)="save($event, AnswersResponses)" />
  </mat-form-field>
</form>

This is my TypeScript code:

save(event, profileResponse: GetAnswersResponses) {
if (!this.singleTextForm.pristine){  
     // save data
   };
}

The issue I'm facing is that the this.singleTextForm.pristine state doesn't update until the second keystroke. If the user only changes one character, it doesn't trigger the saving process.

Thank you

SOLUTION THAT WORKED

I followed AJT_82's solution with some tweaks. Here is the code I ended up using:

HTML page:

<form  [formGroup]="singleTextForm">
  <mat-form-field class="text-box-width">    
     <input matInput placeholder="" formControlName="AnswersResponses" (input)="save(AnswersResponses)" [value]="AnswersResponses.answerText" />
  </mat-form-field>
</form>

And here is part of my TypeScript code:

ngOnInit() {
    this.singleTextForm.patchValue({
        AnswersResponses: this.AnswersResponses
          })
}

save(profileResponse: GetAnswersResponses) {

      profileResponse.answerText = this.singleTextForm.value["AnswersResponses"].toString();

  //saving changes to the database
    ...
}

Answer №1

To optimize this code, I recommend maximizing the use of reactive forms and eliminating the need for ngModel. If you are receiving data in the variable AnswersResponses (rather than formcontrol), you can utilize patchValue or setValue to assign the value to your form control upon data reception:

this.singleTextForm.patchValue({
  AnswersResponses: this.AnswersResponses.answerText
})

Next, we can eliminate ngModelChange and instead capture user input using the input event:

<input matInput formControlName="AnswersResponses" (input)="save()" />

In the TypeScript file:

save() {
 console.log(this.singleTextForm.value)
}

Additionally, if making an HTTP call to save data, consider enhancing this further by monitoring changes in the form control with valueChanges, and incorporating debounceTime and distinctUntilChanged to avoid unnecessary HTTP calls when users type rapidly.

Answer №2

Take a moment to see if it needs cleaning. !this.singleTextForm.dirty

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