Display table data from RethinkDB in Phoenix Framework

Question

I'm attempting to display data from my databases in RethinkDB (using the rethinkdb-elixir package from Hamiltop https://github.com/hamiltop/rethinkdb-elixir) in Phoenix. I'm relatively new to both, but I already managed to insert two tables and some data into those tables. I know this because I checked it through RethinkDB's web GUI.

Now I want to display table data in an html page of my project. I've reduced the errors to one:

protocol Phoenix.HTML.Safe not implemented for %RethinkDB.Collection{data: [%{"first_name" => "Carlos", "id" => "4be8adc3-0973-45dc-bdb8-7a4dac6528d5", "last_name" => "Santos"}, %{"first_name" => "Carlos", "id" => "c84658fc-e4a4-4cb6-8107-b011ca996abd", "last_name" => "Santos"}, %{"first_name" => "Carlos", "id" => "c09fe081-379a-4334-97a3-31c5503c8c61", "last_name" => "Santos"}, %{"first_name" => "Carlos", "id" => "cf0c0ad3-3152-40f0-b613-5b051a314b51", "last_name" => "Santos"}, %{"first_name" => "Carlos", "id" => "ca28a714-ed54-4ebd-8707-d53170ead0f7", "last_name" => "Santos"}, %{"first_name" => "Carlos", "id" => "1ea77c0f-538c-4663-be92-499f16996594", "last_name" => "Santos"}, %{"first_name" => "Carlos", "id" => "1ea74846-0860-4ae5-95f5-674860cf7fc6", "last_name" => "Santos"}]}

Clearly it is fetching all the inserted Carlos Santos persons from the table (which I also must prevent but that is not my main issue) but having an error retrieving them to my Phoenix project.

I've got an index page in whose controller I create the tables and data. Then I added a new page: router.ex:

get "/users", UsersController, :users

/views/users_view.ex:

defmodule RethinkExample.UsersView do
  use RethinkExample.Web, :view
end

users.html.eex:

<div class="jumbotron">
  <p><%= @users %>!</p>
</div>

users_controller.ex

defmodule RethinkExample.UsersController do
  use RethinkExample.Web, :controller
  use RethinkDB.Query

    def users(conn, _params) do
        q = table("users")
            |> filter(%{last_name: "Santos"})
            |> RethinkExample.Database.run
        |> IO.inspect
        render conn, "users.html", users: q
    end

end

I deduce that the html code is also incorrect, because this is how I would display the route specific id inside the html tags. How can I fetch the data successfully and then display it in a html tag?

Gazler Gazler · Accepted Answer · 2015-07-17T15:39:58

The problem here is that your data structure in @users is of type %RethinkDB.Collection{} (source) which cannot be output using <%=...%>

You will likely want to iterate over your users to output them. Something like:

<%= for user <- @users.data do %>
  <p><%= "#{user["first_name"]} #{user["last_name"]}" %>!</p>
<% end %>

Here we are using a list comprehension to iterate over all the items on the @users.data array. This is a common way to output an array of elements (such as users, blog posts, comments, etc.) in EEx.

You might also want to consider passing q.data though as @users instead of q to prevent having to do @users.data.

As an aside, you can also use pattern matching inside the list comprehension:

<%= for %{"first_name" => first_name, "last_name" => last_name} <- @users.data do %>
  <p><%= "#{first_name} #{last_name}" %>!</p>
<% end %>

This is useful if you don't plan on using many of the fields in the map.

Display table data from RethinkDB in Phoenix Framework

1 Answers