Preventing Button Clicks in Angular 2 When Form Data is Modified

I am looking to determine if at least one field in my form has been altered. When this condition is met, the disableButton variable will be set to true, and false if there are no changes in the form. Here is the snippet of code I am currently using:

// The array 'this.hold' temporarily stores the initial form values for comparison

if(this.data.process == 'update') {
   for(const f in form.value){
       if (form.value[f] == this.hold[f])
           this.disableButton = true;
       else
           this.disableButton = false;
   }
}

The issue here is that the button only gets disabled when ALL fields have changed. What adjustments should I make to my condition or inside the for loop?

formsangulartypescriptfieldangular-forms

Answer №1

When working with Angular, you can rely on the framework to keep track of form controls values and automatically mark them as dirty if they have been changed. There's no need for manual checking; you can simply access the .dirty property of the form like this:

this.isFormDirty = form.dirty;

To avoid unnecessary changes being flagged as dirty (such as adding and then removing a value), you can use the markAsPristine() method to reset the control to its original pristine state when the value returns to its initial state. You can store the initial values in an object like this:

const initialValues = {prop: 3};
form.valueChanges.subscribe((changes)=>{
    for (prop in changes) {
       if (changes[prop] === initialValues[prop]) {
           form.get(prop).markAsPristine();
       }
    }
});

Answer №2

If you're looking to check for modifications, the pristine property (or its opposite, the dirty property) is what you need. This property is specifically defined within the AbstractControl class and it indicates whether any alterations have been made to your FormControl, FormGroup, or FormArray.

Answer №3

To ensure proper functionality, remember to incorporate a break statement whenever a value is altered.

if(this.data.process == 'update') {
   for(const f in form.value){
       if (form.value[f] == this.hold[f]){
           this.disableButton = true;

       }    
       else{
          this.disableButton = false;
          break;
        }

   }
}

Answer №4

updateInfo: FormGroup;
    this.updateInfo = this.fb.group({
      countryEdit: ['', Validators.required],
      dateEdit: ['', Validators.required],
      holidayNameEdit: ['', Validators.required],
    });
     <div>
    <button [disabled]="!updateInfo.dirty" type="button" class="btn btn-primary save-changes-btn m-t-5">Update</button>
    </div>

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