Encodes nil blobs for updates

lib/ecto/adapters/sqlite3/codec.ex

@@ -92,6 +92,7 @@ defmodule Ecto.Adapters.SQLite3.Codec do
     Application.get_env(:ecto_sqlite3, :json_library, Jason).encode(value)
   end
 
+  def blob_encode(nil), do: {:ok, nil}
   def blob_encode(value), do: {:ok, {:blob, value}}
 
   def bool_encode(nil), do: {:ok, nil}

test/ecto/adapters/sqlite3/codec_test.exs

@@ -210,4 +210,17 @@ defmodule Ecto.Adapters.SQLite3.CodecTest do
       {:ok, "2011-01-09"} = Codec.date_encode(date, :iso8601)
     end
   end
+
+  describe ".blob_encode/1" do
+    test "nil" do
+      {:ok, nil} = Codec.blob_encode(nil)
+    end
+
+    test "valid blob" do
+      {:ok, {:blob, <<>>}} = Codec.blob_encode(<<>>)
+
+      {:ok, {:blob, <<0xDE, 0xAD, 0xBE, 0xEF>>}} =
+        Codec.blob_encode(<<0xDE, 0xAD, 0xBE, 0xEF>>)
+    end
+  end
 end

test/ecto/integration/blob_test.exs

@@ -0,0 +1,24 @@
+defmodule Ecto.Integration.BlobTest do
+  use Ecto.Integration.Case
+
+  alias Ecto.Integration.TestRepo
+  alias EctoSQLite3.Schemas.Setting
+
+  @moduletag :integration
+
+  test "updates blob to nil" do
+    setting =
+      %Setting{}
+      |> Setting.changeset(%{checksum: <<0x00, 0x01>>})
+      |> TestRepo.insert!()
+
+    # Read the record back using ecto and confirm it
+    assert %Setting{checksum: <<0x00, 0x01>>} =
+             TestRepo.get(Setting, setting.id)
+
+    assert %Setting{checksum: nil} =
+             setting
+             |> Setting.changeset(%{checksum: nil})
+             |> TestRepo.update!()
+  end
+end

test/support/migration.ex

@@ -44,6 +44,7 @@ defmodule EctoSQLite3.Integration.Migration do
 
     create table(:settings) do
       add(:properties, :map)
+      add(:checksum, :binary)
     end
   end
 end

test/support/schemas/setting.ex

@@ -7,9 +7,10 @@ defmodule EctoSQLite3.Schemas.Setting do
 
   schema "settings" do
     field(:properties, :map)
+    field(:checksum, :binary)
   end
 
   def changeset(struct, attrs) do
-    cast(struct, attrs, [:properties])
+    cast(struct, attrs, [:properties, :checksum])
   end
 end