Angular 2 - FormControl setValue 'onlySelf' parameter

Question

Trying to understand what the \'onlySelf\' parameter does when passing to setValue.

this.form.get(\'name\').setValue(\'\', { onlySelf: true })

Answer 1

Put it this way, let's say that you have a form, called mainForm which is valid. It has four controls on it and all four have a value. Now, you decide to update the value of one of your controls, let's say you update it to some incorrect value and you specify onlySelf: true. If you try to call this.mainForm.valid, you will get the result that your form is valid even though your control is not valid, and it's invalid state should not allow the form to be submitted. But because the forms valid property is reporting true, you will be submitting inconsistent values to the backend.

It might be confusing why you would have this property, but there might be occasions when you don't want to invalidate the form because of one value or control. Probably you have some advanced checks on the server and you want to correct the value on the server or you might depend on a value from some external web service that might not be available at the time. I'm sure there are number of scenarios but this is something from top of my head.