changing a field value based on state of another one (for repeated, nesting field)

In some cases I want to change the field value (in particular clear it) based on the state of another value.

I think the right way in would be form.on('[e-mail]',.. and then use a clear() on the field I want to clear. But my form is a nested form, and I tried form.on('update@repeated[].value', ... with no luck: it never seems to fire.

As an alternative I tried to hook up events using form.$('repeated[].value').onChange, but the field couldn’t be found in that case.

Two questions:

• are these strategies supposed to work, or am I going about it the wrong way?

• is this a bug concerning nested fields and events?

[faassen]

I took a look at using observable, but there is some complexity here in combination with repeated sub-forms.

I can implement an onInit that uses forEach to go through all fields, including nested ones. These fields become observable. It’s not the most expressive way to make such fields observable (I’d prefer to use the flat specification, like bars[].value), but it could be made to work.

But what happens now if someone adds a field using onAdd? This field is not observable. Instead I have to write more logic to make the values that just got added observable. I’m also not sure what would happen if I remove a field previously declared observable – maybe there’s no problem there.

I see you closed this issue, and I hope I missed something, but this isn’t a very pleasant API when dealing with repeating fields.

I think it would be useful to have a declarative callback, something like:

observers = {
  'entries[].a': (field, parentField, form) =>  { parentField.$('b').value = ""; }
}

To express the following relationship: blank the value b on the entry with the same index when entries[].a changes.

I will now investigate the other approach you suggested, where I override the event handler.

[foxhound87]

Anyway both styles can be used. You can use the ‘observables’ initial object as well, this will allow to enable the observables to the new added fields.