JsonView.render_one

You're seeing just the function render_one, go back to JsonView module for more information.
Link to this function

render_one(resource, view, template)

View Source

Render one item if not nil, similar to Phoenix.View.render_one/3 It invokes the function render(template, %{model_name: data}) in the view module

Example

render_one(user, MyApp.UserView, "user.json") # then invoke MyApp.UserView.render("user.json", %{user: user})