Programming Phoenix LiveView B10.0: Demographic form validation functions are missing (page 215)

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The code for the demographic form concludes on page 215.

Let’s see it in action.

Any change to a form value causes an error. For example I changed female to male.

[debug] HANDLE EVENT "validate" in PentoWeb.SurveyLive
  Component: PentoWeb.DemographicLive.Form
  Parameters: %{"_target" => ["demographic", "gender"], "demographic" => %{"gender" => "male", "year_of_birth" => "2023"}}
[error] GenServer #PID<0.3809.0> terminating
** (FunctionClauseError) no function clause matching in PentoWeb.DemographicLive.Form.handle_event/3
    (pento 0.1.0) lib/pento_web/live/demographic_live/form.ex:28: PentoWeb.DemographicLive.Form.handle_event("validate", ...)
...

pento/lib/pento_web/live/demographic_live/form.ex has no function to handle validation events. This handle_event function and its helper function are available in the book’s downloadable code:

  def handle_event("validate", %{"demographic" => demographic_params}, socket) do
    params = params_with_user_id(demographic_params, socket)
    {:noreply, validate_demographic(socket, params)}
  end

  defp validate_demographic(socket, demographic_params) do
    changeset =
      socket.assigns.demographic
      |> Survey.change_demographic(demographic_params)
      |> Map.put(:action, :validate)

    assign_form(socket, changeset)
  end

Please include these functions in the book.

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