NEW: add get_object and get_object_edge (#65)

Add two new functions to work with generic objects from the Facebook Graph.

This is joint work with @bugduino

lib/facebook.ex

@@ -372,6 +372,59 @@ defmodule Facebook do
     page(page_id, access_token, ["fan_count"])
   end
 
+  @doc """
+  Basic Graph object information by object ID
+
+  ## Example
+      iex> Facebook.get_object("1234567", "<Access Token>")
+      {:ok, %{"id" => id}}
+  """
+  @spec get_object(object_id :: String.t, access_token) :: resp
+  def get_object(object_id, access_token) do
+    get_object(object_id, access_token, [])
+  end
+
+  @doc """
+  Get Graph object information for the specified params for the provided object ID
+
+  ## Example
+      iex> Facebook.get_object("1234567", "<Access Token>", [fields: "id,name"])
+      {:ok, %{"id" => id, "name" => name}
+
+  See: https://developers.facebook.com/docs/graph-api/reference/page
+  """
+  @spec get_object(object_id, access_token, params) :: resp
+  def get_object(object_id, access_token, params) do
+    params = params
+               |> add_app_secret(access_token)
+               |> add_access_token(access_token)
+
+    ~s(/#{object_id})
+      |> GraphAPI.get([], params: params)
+      |> ResponseFormatter.format_response
+  end
+
+  @doc """
+  Gets an object edge for a specific object ID
+
+  ## Examples
+      iex> Facebook.get_object_edge(:adlabels, "act_12345", "<Access Token>")
+      iex> Facebook.page_feed(:leads, "1223344332", "<Access Token>", [fields: "created_time,id,ad_id,form_id,field_data"])
+      {:ok, %{"data" => [...]}}
+
+  """
+  # credo:disable-for-lines:1 Credo.Check.Readability.MaxLineLength
+  @spec get_object_edge(edge :: atom | String.t, object_id :: String.t, access_token, params) :: resp
+  def get_object_edge(edge, object_id, access_token, params \\ []) do
+    params = params
+               |> add_app_secret(access_token)
+               |> add_access_token(access_token)
+
+    ~s(/#{object_id}/#{edge})
+      |> GraphAPI.get([], params: params)
+      |> ResponseFormatter.format_response
+  end
+
   @doc """
   Basic page information for the provided `t:page_id/0`
 
@@ -398,12 +451,7 @@ defmodule Facebook do
   @spec page(page_id, access_token, fields) :: resp
   def page(page_id, access_token, fields) do
     params = [fields: Enum.join(fields, ",")]
-               |> add_app_secret(access_token)
-               |> add_access_token(access_token)
-
-    ~s(/#{page_id})
-      |> GraphAPI.get([], params: params)
-      |> ResponseFormatter.format_response
+    get_object(page_id, access_token, params)
   end
 
   @doc """
@@ -435,12 +483,7 @@ defmodule Facebook do
   @spec page_feed(scope, page_id, access_token, limit, fields :: String.t) :: resp
   def page_feed(scope, page_id, access_token, limit \\ 25, fields \\ "") when limit <= 100 do
     params = [limit: limit, fields: fields]
-               |> add_app_secret(access_token)
-               |> add_access_token(access_token)
-
-    ~s(/#{page_id}/#{scope})
-      |> GraphAPI.get([], params: params)
-      |> ResponseFormatter.format_response
+    get_object_edge(scope, page_id, access_token, params)
   end
 
   @doc """

test/facebook_test.exs

@@ -258,6 +258,87 @@ defmodule FacebookTest do
     end
   end
 
+  describe "get_object" do
+    test "success", %{app_access_token: app_access_token} do
+      with_mock :hackney, GraphMock.mock_options(
+        fn(_) -> GraphMock.get_object(:success) end
+      ) do
+        assert {:ok, %{
+          "id" => id
+        }} = Facebook.get_object("1234567", app_access_token)
+
+        assert(String.length(id) > 0)
+      end
+    end
+
+    test "error", %{invalid_access_token: invalid_access_token} do
+      with_mock :hackney, GraphMock.mock_options(
+        fn(_) -> GraphMock.error() end
+      ) do
+        assert {:error, _} = Facebook.get_object("1234567", invalid_access_token)
+      end
+    end
+  end
+
+  describe "get_object with fields" do
+    test "success", %{app_access_token: app_access_token} do
+      with_mock :hackney, GraphMock.mock_options(
+        fn(_) -> GraphMock.get_object(:success, :with_fields) end
+      ) do
+        assert {:ok, %{
+          "id" => id,
+          "name" => name
+        }} = Facebook.get_object("1234567", app_access_token, [fields: "name"])
+
+        assert(String.length(id) > 0)
+        assert(String.length(name) > 0)
+      end
+    end
+
+    test "error", %{invalid_access_token: invalid_access_token} do
+      with_mock :hackney, GraphMock.mock_options(
+        fn(_) -> GraphMock.error() end
+      ) do
+        assert {:error, _} = Facebook.get_object(
+          "1234567",
+          invalid_access_token,
+          [fields: "name"]
+        )
+      end
+    end
+  end
+
+  describe "get_object_edge" do
+    test "success", %{app_access_token: app_access_token} do
+      with_mock :hackney, GraphMock.mock_options(
+        fn(_) -> GraphMock.get_object_edge(:success) end
+      ) do
+        assert {:ok, %{"data" => [data | _]}} = Facebook.get_object_edge(
+          :adlabels,
+          "act_123456",
+          app_access_token
+        )
+
+        assert %{
+          "id" => _,
+          "name" => _
+        } = data
+      end
+    end
+
+    test "error", %{invalid_access_token: invalid_access_token} do
+      with_mock :hackney, GraphMock.mock_options(
+        fn(_) -> GraphMock.error() end
+      ) do
+        assert {:error, _} = Facebook.get_object_edge(
+          :adlabels,
+          "act_123456",
+          invalid_access_token
+        )
+      end
+    end
+  end
+
   describe "page" do
     test "success", %{app_access_token: app_access_token} do
       with_mock :hackney, GraphMock.mock_options(

test/graph_mock.ex

@@ -55,6 +55,25 @@ defmodule Facebook.GraphMock do
     })
   end
 
+  def get_object(:success) do
+    JSON.encode(%{
+      "id": "1234567"
+    })
+  end
+
+  def get_object(:success, :with_fields) do
+    JSON.encode(%{
+      "id": "1234567",
+      "name": "name"
+    })
+  end
+
+  def get_object_edge(:success) do
+    JSON.encode(%{"data": [
+      %{"id": "1234567", "name": "label1"}
+    ]})
+  end
+
   def page(:success) do
     JSON.encode(%{
       "id": "19292868552", "name": "Facebook for Developers"