Permit holding custom data in options

[frerich]

When using the <:option> slot, it is convenient to be able to store other data in the options solely for customising the rendering of an option. E.g.:

  def handle_event("live_select_change", %{"id" => select_id, "text" => text}, socket) do
    students = fetch_student_suggestions(text)

    options = Enum.map(suggestions, &%{label: &1.full_name, value: &1.id, student: &1})
    # ...
  end

  def render(assigns) do
    ~H"""
      <LiveSelect.live_select field={f[:student_id]} >
        <:option :let={option}>
          <.student student={option.student} />
        </:option>
      </LiveSelect.live_select>
    """
  end

However, all fields in an option currently need to support encoding to JSON since the list of selected options is sent to the client. Thus, only custom data fields which support encoding to JSON can be included in the options.

This commit changes that by cleansing the set of selected options before sending them to the client: any fields other than

• :label
• :value
• :disabled
• :tag_label

are omitted, the first three seem to be the 'canonical set' which the normalize_option/1 function returns, :tag_label is a supported optional field.

That way, whatever custom data is stored on options for customising the rendering is not sent to the client - and does not require defining a protocol implementation for e.g. Jason.Encoder either.

[frerich]

An alternative approach which is maybe easier to maintain would be to add recognition of a new dedicated field for options, like render_data or such. That way, only that specific value would need to be omitted from the event to the client, i.e. the code can use an exclusion list rather than an inclusion list which might be more open to future extensions.