__struct__/1 is undefined, cannot expand struct Gazette.User

Question

I am building a Phoenix 1.3 app but following a 1.2 Pheonix tutorial, I ran deprecated commands like mix phoenix.gen.model

I am not sure if it is linked but now I get this error:

== Compilation error in file lib/gazette_web/controllers/user_controller.ex ==
** (CompileError) lib/gazette_web/controllers/user_controller.ex:12: Gazette.User.__struct__/1 is undefined, cannot expand struct Gazette.User
    lib/gazette_web/controllers/user_controller.ex:11: (module)
    (stdlib) erl_eval.erl:670: :erl_eval.do_apply/6
    (elixir) lib/kernel/parallel_compiler.ex:121: anonymous fn/4 in Kernel.ParallelCompiler.spawn_compilers/1

Here is my user_controller.ex file:

defmodule Gazette.UserController do
  use GazetteWeb, :controller

  alias Gazette.User

  def show(conn, %{"id" => id}) do
    user = Repo.get!(User,id)
    render(conn, "show.html", user: user)
  end

  def new(conn, _params) do
    changeset = User.changeset(%User{})
    render conn, "new.html", changeset: changeset
  end

  def create(conn, %{"user" => user_params}) do
    # here will be an implementation
  end
end

and this is my model/user.ex file:

defmodule Gazette.User do
  use Gazette.Web, :model

  schema "users" do
    field :email, :string
    field :name, :string
    field :password, :string, virtual: true
    field :password_hash, :string
    field :is_admin, :string
    field :is_writer, :string

    has_many :posts, Gazette.Post

    timestamps()
  end

  @required_fields ~w(email name)a
  @optional_fields ~w(is_admin is_writer)a

  @doc """
  Builds a changeset based on the `struct` and `params`.
  """
  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, @required_fields ++ @optional_fields)
    |> validate_required(@required_fields)
  end
end

any idea ?

Answer 1

Your Gazette.User is a regular module, it won’t be turned to the struct automagically. To make an Ecto schema out of it, you need to:

use Ecto.Schema

I am unsure what use Gazette.Web, :model does, but I believe it’s deprecated or something. It’s always better to be explicit when defining schemas.

You might also want/need to:

import Ecto.Changeset
import Ecto.Query

This code may have been autogenerated using the old mix phx.gen.model task. Instead, you want to use mix phx.gen.schema in order to get the correct boilerplate.