Phoenix Framework - How to update a record in a database and use the PATCH method?

Question

I'm building an app using the Phoenix Framework and I've done all the CRUD action but the Update/Edit one. I've read and the done the Programming Phoenix book but I still can't do the update action. I think the problem is that I need to override the POST method somehow.

This is my changeset for updating:

        def changeset_update(model, params \\ :empty) do
        model
        |> cast(params, [], [])
        |> validate_length(:username, min: 1, max: 20)
        end

My action in the controller:

    def update(conn, %{"user" => user_params, "id" => id}) do
    user      = Repo.get!(User, id) 
    changeset = User.changeset_update(%User{}, user_params)
    IO.puts changeset.valid?

    case Repo.update(changeset) do 
        {:ok, user} ->
            conn
            |> put_flash(:info, "#{user.name} updated successfully!")
            |> redirect(to: user_path(conn, :show, id: id))
        {:error, changeset} ->
            render conn, "edit.html", changeset: changeset, user: user
    end
    end

and my page:

<h1>Edit User</h1>

<%= form_for @changeset, admin_path(@conn, :update, @user), fn f -> %>
	<%= if @changeset.action do %>
    <div class="alert alert-danger">
      <p>Oops, something went wrong! Please check the errors below:</p>
      <ul>
        <%= for {attr, message} <- f.errors do %>
          <li><%= humanize(attr) %> <%= message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

	<div class="form-group">
		<input type="hidden" name="_method" value="patch">
			<%= text_input f, :name, placeholder: @user.name, 
				class: "form-control" %>

			<%= text_input f, :username, placeholder: @user.username, 
				class: "form-control" %>

			<%= email_input f, :email, placeholder: @user.email, 
				class: "form-control" %>

			<%= text_input f, :client, placeholder: @user.client, 
				class: "form-control" %>

			<%= number_input f, :role, placeholder: @user.role, 
				class: "form-control" %>

			<button type="submit" class="btn btn-primary">Save</button>
	</div>
<% end %>	

<%= link "Update", to: admin_path(@conn, :update, @user.id),
	method: :update, data: [confirm: "Update this user's record?"], 
			class: "btn btn-default btn-xs" %>

(I actually have two buttons because I was trying both ways)

With the first button I get:

    Protocol.UndefinedError at PATCH /admin/users/13

    protocol Phoenix.Param not implemented for [id: "13"]

But I do have the route /admin/users/:id for the :update action in my routes.ex

With the second button I get:

    Phoenix.Router.NoRouteError at POST /admin/users/13

    no route found for POST /admin/users/13 (MyApp.Router)

Which is normal I guess, since I don't have that route for POST.

Can anyone help me solve this please?

Answer 1

Your PATCH version actually works and gets routed to the update action. The problem is in the line

|> redirect(to: user_path(conn, :show, id: id))

Change that to

|> redirect(to: user_path(conn, :show, id)

and you should be good :-)