在Phoenix / Elixir中创建性别下拉菜单会导致“分配@all_genders在eex模板中不可用。”

Question

我想将性别添加到来自数据库（和其他查找表）的客户端中

我已经将客户定义为：

defmodule Dropdown.Clients.Client do
  use Ecto.Schema
  import Ecto.Changeset
  alias Dropdown.Clients.Admin

  schema "clients" do
    field :email, :string
    field :name, :string

    belongs_to :genders, Admin

和性别

defmodule Dropdown.Clients.Admin do
  use Ecto.Schema
  import Ecto.Changeset

  schema "gender" do
    field :gender, :string
    has_many :clients, Client
  end

控制器添加和创建功能如下：

  def new(conn, _params) do
    changeset = Clients.change_client(%Client{})
    gender_query = from g in Admin, select: {g.gender, g.id}
    all_genders = Dropdown.Repo.all(gender_query)

    render(conn, "new.html", all_genders: all_genders, changeset: changeset)
  end

  def create(conn, %{"client" => client_params}) do

    case Clients.create_client(client_params) do
      {:ok, client} ->
        conn
        |> put_flash(:info, "Client created successfully.")
        |> redirect(to: Routes.client_path(conn, :show, client))

      {:error, %Ecto.Changeset{} = changeset} ->
        render(conn, "new.html", changeset: changeset)
    end
  end

相应的上下文是：

    Client
    |> Repo.get!(id)
    |> Repo.preload(:genders)
  end

  def create_client(attrs \\ %{}) do
    %Client{}
    |> IO.inspect()
    |> Client.changeset(attrs)
    |> Repo.insert()
  end

在添加表单中：

  <%= select(f, :gender_id, @all_genders) %>
  <%= error_tag f, :gender_id %>

我的表单显示性别下拉列表，但是，当我提交时出现错误：

分配@all_genders在eex模板中不可用。

IO.inspect显示：

  [debug] Processing with DropdownWeb.ClientController.create/2
  Parameters: %{"_csrf_token" => "ECAXCnJJEw1ZGRtyFmoZDDF_GjQ3CHFzqvxrAypk0JW5N3kkE1UytpBJ", "client" => %{"email" => "[email protected]", "gender_id" => "1", "name" => "George Company"}}
  Pipelines: [:browser]

任何解决此问题的建议将不胜感激。

Answer 1

在您的错误情况下（Client.create_client/1返回错误元组时，您将再次渲染new.html模板。但是，您没有提供all_genders分配（键：值），因此当它尝试渲染时，它崩溃了。

您还必须修改控制器以在错误情况下也包含all_genders：

def new(conn, _params) do
  changeset = Clients.change_client(%Client{})
  gender_query = from g in Admin, select: {g.gender, g.id}
  all_genders = Dropdown.Repo.all(gender_query)

  render(conn, "new.html", all_genders: all_genders, changeset: changeset)
end

def create(conn, %{"client" => client_params}) do
  case Clients.create_client(client_params) do
    {:ok, client} ->
      conn
      |> put_flash(:info, "Client created successfully.")
      |> redirect(to: Routes.client_path(conn, :show, client))

    {:error, %Ecto.Changeset{} = changeset} ->
      # This part was missing in your original code
      gender_query = from g in Admin, select: {g.gender, g.id}
      all_genders = Dropdown.Repo.all(gender_query)
      # -----------
      render(conn, "new.html", changeset: changeset, all_genders: all_genders)
  end
end