将变换集数据绑定到隐藏的输入值

Question

我遇到了以下问题。我正在尝试将一些日期从变更集中绑定到隐藏字段。但我只得到隐藏的字段，没有任何值。

型号：

schema "events" do
    field :name, :string
    field :address, :string

    field :location_x, :float
    field :location_y, :float

    field :date, Ecto.DateTime

    field :description, :string

    has_many :presences, Presence
    has_many :users, through: [:presences, :user]
  end

形式：

<%= form_for @changeset, @action, fn f -> %>
  <!-- some unrealted code -->

  <div class="form-group">
    <%= label f, :description, "Description", class: "control-label" %>
    <%= text_input f, :description, class: "form-control" %>
  </div>

  <%= hidden_input f, :location_y, id: "location_y", value: @changeset.model.location_y %>
  <%= hidden_input f, :location_x, id: "location_x" %>

  <div class="form-group">
    <%= submit "Submit", class: "btn btn-primary" %>
  </div>
<% end %>

正如您所看到的，我尝试过手动应用值：但也没有用。我看过和文档，我发现的只有“生成隐藏的输入”。所以假设它的行为与其他输入一样。

事件：

defmodule Kpsz.Model.Event do
  use Kpsz.Web, :model

  alias Kpsz.Model.Presence

  schema "events" do
    field :name, :string
    field :address, :string

    field :location_x, :float
    field :location_y, :float

    field :date, Ecto.DateTime

    field :description, :string

    has_many :presences, Presence
    has_many :users, through: [:presences, :user]
  end

  @required_fields ~w(name address date description)
  @optional_fields ~w(location_x location_y)

  def changeset(user, params \\ :empty) do
    user
      |> cast(params, @required_fields, @optional_fields)
      |> unique_constraint(:name)
  end
end

控制器：

defmodule Kpsz.EventController do
  use Kpsz.Web, :controller

  import Kpsz.Authorize

  plug :logged
  plug :authorized_admin when action in [:new, :create, :edit, :update, :delete]

  alias Kpsz.Model.Event

  plug :scrub_params, "event" when action in [:create, :update]

  def index(conn, _params) do
    query = from w in Event,
     select: w
    events = Repo.all(query)
    render(conn, "index.html", events: events)
  end

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

  def create(conn, %{"event" => event_params}) do
    changeset = Event.changeset(%Event{}, event_params)

    case Repo.insert(changeset) do
      {:ok, _event} ->
        conn
        |> put_flash(:info, "Event created successfully.")
        |> redirect(to: event_path(conn, :index))
      {:error, changeset} ->
        render(conn, "new.html", changeset: changeset)
    end
  end

  def show(conn, %{"id" => id}) do
    event = Repo.get!(Event, id) |> Repo.preload([:users])
    IO.inspect(event)
    render(conn, "show.html", event: event)
  end

  def edit(conn, %{"id" => id}) do
    event = Repo.get!(Event, id)
    changeset = Event.changeset(event)
    render(conn, "edit.html", event: event, changeset: changeset)
  end

  def update(conn, %{"id" => id, "event" => event_params}) do
    event = Repo.get!(Event, id)
    changeset = Event.changeset(event, event_params)

    case Repo.update(changeset) do
      {:ok, event} ->
        conn
        |> put_flash(:info, "Event updated successfully.")
        |> redirect(to: event_path(conn, :show, event))
      {:error, changeset} ->
        render(conn, "edit.html", event: event, changeset: changeset)
    end
  end

  def delete(conn, %{"id" => id}) do
    event = Repo.get!(Event, id)

    # Here we use delete! (with a bang) because we expect
    # it to always work (and if it does not, it will raise).
    Repo.delete!(event)

    conn
    |> put_flash(:info, "Event deleted successfully.")
    |> redirect(to: event_path(conn, :index))
  end

end