A button that populates a form field

Phoenix Forum Questions / Help
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1

I have a form backed by a changeset like mentioned here Form bindings — Phoenix LiveView v0.15.7
Say I want a button <button phx-click="foo">Foo</button> that will populate email with some value. Problem is I do not want this button to submit the form. Hence params will not contain the form data and without the form data I cannot create new changeset and update socket with it like the other handlers for save or validate

def handle_event("foo", params, socket) do
    IO.inspect(params) #%{"value" => ""}
    {:noreply, socket}
  end

Any ideas how I can do this?

2

You can use a phx-change handler to save the part you need later in your socket assigns, when the user press the foo button you can then use those info in your foo handler.

3

If you don’t want the button to submit the form, be sure to add type="button" to replace the default type of "submit".

2 Likes
4

Also just to give an example for the solution derek mentioned above:

Assuming you have validation for your form similar to this

def handle_event("validate", %{"user" => params}, socket) do
  changeset =
    %User{}
    |> Users.change_user(params)
    |> Map.put(:action, :insert)

  {:noreply, assign(socket, changeset: changeset)}
end

then there should be an up-to-date changeset within the socket assigns. Therefore you can use the changeset assign in your handle_event/3

def handle_event("foo", params, socket) do
  new_changeset = socket.assigns.changeset |> some_functions

  {:noreply, assign(socket, changeset: new_changeset)}
end
1 Like
5

Thank guys. I am having a :man_facepalming: moment right now.