Preparatory work

lib/birdy_chat_web/api/messages/controller.ex

@@ -0,0 +1,20 @@
+defmodule BirdyChatWeb.Api.Messages.Controller do
+  use BirdyChatWeb, :controller
+
+  def create(conn, params) do
+    case BirdyChat.Message.validate(params) do
+      {:ok, changeset} ->
+        case BirdyChat.Message.write(changeset.changes) do
+          {:ok, msg} ->
+            conn
+            |> put_status(:created)
+            |> render(:create, message: msg)
+        end
+
+      {:error, changeset} ->
+        conn
+        |> put_status(:unprocessable_entity)
+        |> render(:error, changeset: changeset)
+    end
+  end
+end

lib/birdy_chat_web/api/messages/json.ex

@@ -0,0 +1,14 @@
+defmodule BirdyChatWeb.Api.Messages.JSON do
+  def render("create.json", %{message: message}) do
+    message
+  end
+
+  def render("error.json", %{changeset: changeset}) do
+    errors = Ecto.Changeset.traverse_errors(changeset, &get_error/1)
+    %{errors: errors}
+  end
+
+  def get_error({msg, opts}) do
+    Gettext.dgettext(BirdyChatWeb.Gettext, "errors", msg, opts)
+  end
+end

lib/birdy_chat_web/router.ex

@@ -20,6 +20,12 @@ defmodule BirdyChatWeb.Router do
     get "/", PageController, :home
   end
 
+  scope "/api", BirdyChatWeb.Api do
+    pipe_through [:api]
+
+    post "/messages", Messages.Controller, :create
+  end
+
   # Other scopes may use custom stacks.
   # scope "/api", BirdyChatWeb do
   #   pipe_through :api