Add Render A Template To A String as a phoenix til

phoenix/render-a-template-to-a-string.md

@@ -0,0 +1,24 @@
+# Render A Template To A String
+
+Templates in a Phoenix application ultimately get compiled to functions that
+can be quickly rendered with the necessary data. We can take a look at how a
+template will be rendered using
+[`Phoenix.View.render_to_string/3`](https://hexdocs.pm/phoenix/Phoenix.View.html#render_to_string/3).
+
+First, we need a template:
+
+```elixir
+# user.html.eex
+<h1><%= @user.first_name %></h1>
+<h5><%= @user.username %> (<%= @user.email %>)</h5>
+```
+
+We can then render that template for the view with some user:
+
+```elixir
+> user = %User{first_name: "Liz", last_name: "Lemon", username: "llemon", email: "lizlemon@nbc.com"}
+%MyApp.User{...}
+
+> Phoenix.View.Render_to_string(MyApp.UserView, "user.html", user: user)
+"<h1>Liz</h1>\n<h5>llemon (lizlemon@nbc.com)</h5>\n"
+```