How do i check if a variable exist, in eex?

Question

I\'m working on the crud part of a model, to which i\'ve added image support to. Ideally i would like to show the image if you are editing a model, which i would do like this.

Answer 1

The selected answer doesn't work.

Try with this :

<%= if Map.has_key?(assigns, :company) do %>
  <%= Logo.url({@company.logo, @company}, :thumb) %>
<% end %>

Answer 2

EDIT Prior to Phoenix 0.14.0 @company would return nil if it was not set. It was changed to raise so that the assignment would be explicit (explicit over implicit.)

---

If you use either @company or assigns.company then an error will be raised. However if you use assigns[:company] then it will return nil if the value is not set.

<%= if assigns[:company] do %>
  <%= Logo.url({@company.logo, @company}, :thumb) %>
<% end %>

It is worth noting that if you are using a nested template then you will need to pass this through too:

<h1>New thing</h1>
<%= render "form.html", changeset: @changeset,
                        action: thing_path(@conn, :create),
                        company: assigns[:company] %>