Hello,

I am new to LiveView, Phoenix and Elixir, and I am struggling to populate the UI from the form contents. Here’s a simplified version of what I have in my code:

I have defined a struct with some simple fields:

defmodule MyApp.MyStruct do
  defstruct some_integer: 3,
            some_string: "",
            some_bool: true
end

Then I have a context:

defmodule MyApp.Context do
  alias MyApp.MyStruct

  def current_struct() do
    %MyStruct{}
  end
end

It simply returns the newly created struct with default values. Now, I need to display a form populated with these values + allow modifying them. This is my _live.ex file:

defmodule MyAppWeb.ViewLive do
  alias MyApp.MyStruct
  use MyAppWeb, :live_view

  def mount(_params, _session, socket) do
    {:ok, assign(socket, form: to_form(Map.from_struct(Context.current_struct())))}
  end

  # Here I have handle_event methods, but they don't do anything at the moment.
end

Finally, this is the .heex file:

<div class="container mx-auto my-4">
  <.form for={@form} phx-change="change_form" phx-submit="submit_form">
    <!-- Number picker -->
    <div class="mb-4">
      <.label>I want to pick a number here:</.label>
    </div>
    <div class="flex items-center space-x-4 mb-4">
      <label class="cursor-pointer">
    <input type="radio" name="some_integer" value="3" class="hidden" checked={Context.current_struct().some_integer == 3}
    />
        <span class={"px-4 py-2 rounded-md #{if Context.current_struct().some_integer == 3, do: "bg-gray-400", else: "bg-gray-200"} hover:bg-gray-400"}>
          3 of something
        </span>
      </label>
      <!-- More of these integer options -->

    <!-- Checkbox -->
    <div class="mb-4">
      <.input
        label="I'd like this to be true or false:"
        type="checkbox"
        value={Context.current_struct().some_bool}
        field={@form[:some_bool]}
      />
    </div>

    <.button>Submit</.button>
  </.form>
</div>

The code above kind of works now for initial values, but it stops working when I select 7 or 10 instead of 3. Note how to get the value or compute background colours I use Context.current_struct() for calculations. I assume, that if I implement handle_event("change_form"...) and modify my current_struct() on each change and save it into the socket, then I could reference that saved struct in the heex template. But I would like to modify the actual struct only on submit, and in the meantime to get the data from the @form. I tried to do that, but failed.

When I try to do something like

value={@form[:some_bool]}

the code crashes.
When I try to use input_value(), then I always get nil, even if inspect(form) shows that both some_integer and some_bool have the values that I expect them to have.

Please advise me how I can achieve this.