I just found myself in a situation where I also needed to use “partial templates” and I remembered this post. This solution worked well, but if you need something that is in “assigns” within the partial template, here is one way that I found, for anyone interested.
For example, let’s say the partial is “_menu_user_management” and it needs access to @current_user. Here is how the parent template can pass it on to it:
<._menu_user_management {assigns}>
or like in the link you provided:
<._menu_user_management current_user={@current_user} />
