You probably want to write:

  alias MyAppWeb.MyPageView

I’m almost sure that’s it. It happens when you are copying some module in other namespace and then you are aliasing it by hand having in mind standard alias … At least I have made such mistake few times …

As far as I can remember, you need to add the alias to the view-module responsible to render the template.

I did that. Here in the question this is a typo.

What alias? Alias of a module to that very module? This won’t work

defmodule MyAppWeb.MyPageView
  alias MyAppWeb.MyPageView
end

The template you are rendering and where you want to call render in, that belongs to a view, and in that view you need to alias.

To alias where?

controller

  defmodule MyAppWeb.MyHomeController do
    alias MyAppWeb.MyHomeView


    def index(conn, params) do
      render(conn, "index.html")
    end
  end

html “home/index.html.eex”:

    <%= render(MyAppWeb.MyHomeView, "_test1.html", data: [1, 2, 3]) %>

Doesn’t work - module MyAppWeb.MyHomeView not found

That’s because templates are compiled into the *View module, not the *Controller module. Put the alias in your *View module. Remember that each template file because another render/2 case in the render/2 function that is in the *View modules.

Yep! I do it quite a lot for my helper modules. ^.^

What issue were you having?

Because templates compile as render/2 function calls inside your View module.

Literally, compiling a file like my_templates/index.html.eex that contains <blah><%= @i %> </blah> compiles into your view file like:

defmodule MyView do

  ... other stuff

  def render("index.html", assigns) do
    ~E"""
    <blah><%= assigns[:i] %> </blah>
    """
  end

  ... more stuff
end

Then please show us a minimal project that causes the error.