Add support for nil value in datetime column

CHANGELOG.md

@@ -7,6 +7,8 @@ project adheres to [Semantic Versioning][semver].
 
 ## Unreleased
 
+- added: Support for encoding nil values in `:utc_datetime`, `:utc_datetime_usec`, `:naive_datetime`, and `:naive_datetime_usec` column dates.
+
 ## v0.13.0
 
 - added: Support fragment splicing.

lib/ecto/adapters/sqlite3/codec.ex

@@ -110,6 +110,9 @@ defmodule Ecto.Adapters.SQLite3.Codec do
 
   @text_datetime_format "%Y-%m-%d %H:%M:%S"
 
+  def utc_datetime_encode(nil, :iso8601), do: {:ok, nil}
+  def utc_datetime_encode(nil, :text_datetime), do: {:ok, nil}
+
   def utc_datetime_encode(%{time_zone: "Etc/UTC"} = value, :iso8601) do
     {:ok, NaiveDateTime.to_iso8601(value)}
   end
@@ -123,6 +126,9 @@ defmodule Ecto.Adapters.SQLite3.Codec do
           "expected datetime type to be either `:iso8601` or `:text_datetime`, but received #{inspect(type)}"
   end
 
+  def naive_datetime_encode(nil, :iso8601), do: {:ok, nil}
+  def naive_datetime_encode(nil, :text_datetime), do: {:ok, nil}
+
   def naive_datetime_encode(value, :iso8601) do
     {:ok, NaiveDateTime.to_iso8601(value)}
   end

test/ecto/adapters/sqlite3/codec_test.exs

@@ -132,6 +132,11 @@ defmodule Ecto.Adapters.SQLite3.CodecTest do
       [dt: ~U[2021-08-25 10:58:59Z]]
     end
 
+    test "nil" do
+      assert {:ok, nil} = Codec.utc_datetime_encode(nil, :iso8601)
+      assert {:ok, nil} = Codec.utc_datetime_encode(nil, :text_datetime)
+    end
+
     test "iso8601", %{dt: dt} do
       dt_str = "2021-08-25T10:58:59"
       assert {:ok, ^dt_str} = Codec.utc_datetime_encode(dt, :iso8601)
@@ -157,6 +162,11 @@ defmodule Ecto.Adapters.SQLite3.CodecTest do
       [dt: ~U[2021-08-25 10:58:59Z], dt_str: "2021-08-25T10:58:59"]
     end
 
+    test "nil" do
+      assert {:ok, nil} = Codec.naive_datetime_encode(nil, :iso8601)
+      assert {:ok, nil} = Codec.naive_datetime_encode(nil, :text_datetime)
+    end
+
     test "iso8601", %{dt: dt} do
       dt_str = "2021-08-25T10:58:59"
       assert {:ok, ^dt_str} = Codec.naive_datetime_encode(dt, :iso8601)

test/ecto/integration/timestamps_test.exs

@@ -123,6 +123,28 @@ defmodule Ecto.Integration.TimestampsTest do
     assert user
   end
 
+  test "insert and fetch nil values" do
+    now = DateTime.utc_now()
+
+    {:ok, product} =
+      %Product{}
+      |> Product.changeset(%{name: "Nil Date Test", approved_at: now, ordered_at: now})
+      |> TestRepo.insert()
+
+    product = TestRepo.get(Product, product.id)
+    assert product.name == "Nil Date Test"
+    assert product.approved_at != now
+    assert product.ordered_at != now
+    assert product.approved_at == DateTime.truncate(now, :second) |> DateTime.to_naive()
+    assert product.ordered_at == DateTime.truncate(now, :second)
+
+    changeset = Product.changeset(product, %{approved_at: nil, ordered_at: nil})
+    TestRepo.update(changeset)
+    product = TestRepo.get(Product, product.id)
+    assert product.approved_at == nil
+    assert product.ordered_at == nil
+  end
+
   test "datetime comparisons" do
     account =
       %Account{}

test/support/migration.ex

@@ -31,6 +31,7 @@ defmodule EctoSQLite3.Integration.Migration do
       add(:bid, :binary_id)
       add(:tags, {:array, :string})
       add(:approved_at, :naive_datetime)
+      add(:ordered_at, :utc_datetime)
       add(:price, :decimal)
       timestamps()
     end

test/support/schemas/product.ex

@@ -14,6 +14,7 @@ defmodule EctoSQLite3.Schemas.Product do
     field(:bid, :binary_id)
     field(:tags, {:array, :string}, default: [])
     field(:approved_at, :naive_datetime)
+    field(:ordered_at, :utc_datetime)
     field(:price, :decimal)
 
     belongs_to(:account, Account)
@@ -23,7 +24,7 @@ defmodule EctoSQLite3.Schemas.Product do
 
   def changeset(struct, attrs) do
     struct
-    |> cast(attrs, [:name, :description, :tags, :account_id, :approved_at])
+    |> cast(attrs, [:name, :description, :tags, :account_id, :approved_at, :ordered_at])
     |> validate_required([:name])
     |> maybe_generate_external_id()
   end