elixir - Access foreign relationship field through template -

let's have model in phoenix app.

defmodule rumbl.video   use rumbl.web, :model    schema "videos"     field :url, :string     field :title, :string     field :description, :string     belongs_to :user, rumbl.user     belongs_to :category, rumbl.category      timestamps()   end    @required_fields ~w(url title description)   @optional_fields ~w(category_id)    def changeset(model, params \\ :empty)     model     |> cast(params, @required_fields, @optional_fields)   end  end 

and category field represents relationship category model has field called name.

then in template have this:

<%= video <- @videos %>     <tr>       <td><%= video.user_id %></td>       <td><%= video.url %></td>       <td><%= video.title %></td>       <td><%= video.description %></td>       <td><%= video.category_id %></td>        <td class="text-right">         <%= link "show", to: video_path(@conn, :show, video), class: "btn btn-default btn-xs" %>         <%= link "edit", to: video_path(@conn, :edit, video), class: "btn btn-default btn-xs" %>         <%= link "delete", to: video_path(@conn, :delete, video), method: :delete, data: [confirm: "are sure?"], class: "btn btn-danger btn-xs" %>       </td>     </tr> <% end %> 

as can see, can access video.category_id

how can access video.category.name make more human readable?

edit: video controller index , categories part

defmodule rumbl.videocontroller   use rumbl.web, :controller    alias rumbl.video    def action(conn, _)     apply(__module__, action_name(conn),           [conn, conn.params, conn.assigns.current_user])   end    def index(conn, _params, user)     videos = repo.all(user_videos(user)) |> repo.preload(:category)     render(conn, "index.html", videos: videos)   end    alias rumbl.category    plug :load_categories when action in  [:new, :create, :edit, :update]    defp load_categories(conn, _)     query =       category       |> category.alphabetical       |> category.names_and_ids     categories = repo.all query     assign(conn, :categories, categories)   end end 

i'm assuming you're loading videos in controller:

videos = repo.all(video) 

this not load associated records. that, can use repo.preload:

videos = repo.all(video) |> repo.preload(:category) 

now each video have category field loaded fields , can <%= video.category.name %> in template.