如何从 url 中获取值并将它们传递给行动？

Question

我想填写用于创建评论正文的 html 表单，这样我就可以通过知道 thread_id 和 user_id 将其插入到 db 中。现在我无法获取thread_id即使它在 url 中。

现在，我的路线如下所示：

        thread_path  GET     /manage/thread                               Rumbl.ThreadController :index
        thread_path  GET     /manage/thread/:id/edit                      Rumbl.ThreadController :edit
        thread_path  GET     /manage/thread/new                           Rumbl.ThreadController :new
        thread_path  GET     /manage/thread/:id                           Rumbl.ThreadController :show
        thread_path  POST    /manage/thread                               Rumbl.ThreadController :create
        thread_path  PATCH   /manage/thread/:id                           Rumbl.ThreadController :update
                     PUT     /manage/thread/:id                           Rumbl.ThreadController :update
        thread_path  DELETE  /manage/thread/:id                           Rumbl.ThreadController :delete
thread_comment_path  GET     /manage/thread/:thread_id/comments           Rumbl.CommentController :index
thread_comment_path  GET     /manage/thread/:thread_id/comments/:id/edit  Rumbl.CommentController :edit
thread_comment_path  GET     /manage/thread/:thread_id/comments/new       Rumbl.CommentController :new
thread_comment_path  GET     /manage/thread/:thread_id/comments/:id       Rumbl.CommentController :show
thread_comment_path  POST    /manage/thread/:thread_id/comments           Rumbl.CommentController :create
thread_comment_path  DELETE  /manage/thread/:thread_id/comments/:id       Rumbl.CommentController :delete

控制器中的动作看起来像这样

  def new(conn, %{"thread_id" => thread_id}) do
    changeset = Comment.changeset(
      %Comment{}, 
      %{user_id: conn.assigns.current_user.id,
        thread_id: thread_id
      })      
    render(conn,"new.html", changeset: changeset)
  end

  def create(conn, %{"comment" => %{"content" => content}, "thread_id"=> thread_id}) do
    user_id = conn.assigns.current_user.id
    changeset = Comment.changeset(
      %Comment{
        content: content,
        user_id: user_id,
        thread_id: to_integer(thread_id)
      })

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

来自网址http://localhost:4000/manage/thread/7/comments/new 我应该得到thread_id = 7，但我得到的是thread_id = 1内部操作create/2，用于模式匹配"thread_id"=> thread_id。内部动作 new/2 我有来自她的模式匹配的thread_id = 7，所以我想通过连接发送它，但那不起作用。我猜是因为 new.html 中的新 conn 被返回了？

这里也是那个new.html文件

<h2>New comment</h2>
<%= form_for @changeset, thread_comment_path(@conn,:create, @current_user), fn f -> %>

    <%= if @changeset.action do %>
    <div class="alert alert-danger">
        <p>Oops, something went wrong! Please check the errors below.</p>
    </div>
    <% end %>

  <div class="form-group">
    <%= label f, :content, class: "control-label" %>
    <%= textarea f, :content, class: "form-control" %>
    <%= error_tag f, :content %>
  </div>
    <%= submit "Create Comment", class: "btn btn-primary" %>
<% end %>

Answer 1

我已经设法使用 Ecto.Changeset changes 字段获得了 thread_id。

<%= form_for @changeset, thread_comment_path(@conn,:create, @changeset.changes.thread_id), fn f -> %>

但是，这是一种解决方法，方法是从操作 new/2 发送变更集，而不是真正从 URL /manage/thread/7/comments/new 获取 thread_id。