From a45267441ab3184f7fef751214b3f5d08535633b Mon Sep 17 00:00:00 2001
From: Zach Daniel <zach@zachdaniel.dev>
Date: Fri, 3 Mar 2023 11:59:15 -0500
Subject: [PATCH] chore: more fluent datetime type casting

---
 lib/ash/type/utc_datetime.ex      | 12 ++++++++++++
 lib/ash/type/utc_datetime_usec.ex | 12 ++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/lib/ash/type/utc_datetime.ex b/lib/ash/type/utc_datetime.ex
index a59846e1..b9551236 100644
--- a/lib/ash/type/utc_datetime.ex
+++ b/lib/ash/type/utc_datetime.ex
@@ -6,6 +6,8 @@ defmodule Ash.Type.UtcDatetime do
   """
   use Ash.Type
 
+  @beginning_of_day Time.new!(0, 0, 0)
+
   @impl true
   def storage_type, do: :utc_datetime
 
@@ -17,6 +19,16 @@ defmodule Ash.Type.UtcDatetime do
   end
 
   @impl true
+  def cast_input(%Date{} = date, constraints) do
+    case DateTime.new(date, @beginning_of_day) do
+      {:ok, value} ->
+        cast_input(value, constraints)
+
+      _ ->
+        {:error, "Date could not be converted to datetime"}
+    end
+  end
+
   def cast_input(value, _) do
     Ecto.Type.cast(:utc_datetime, value)
   end
diff --git a/lib/ash/type/utc_datetime_usec.ex b/lib/ash/type/utc_datetime_usec.ex
index d4cea5a1..12807d17 100644
--- a/lib/ash/type/utc_datetime_usec.ex
+++ b/lib/ash/type/utc_datetime_usec.ex
@@ -6,6 +6,8 @@ defmodule Ash.Type.UtcDatetimeUsec do
   """
   use Ash.Type
 
+  @beginning_of_day Time.new!(0, 0, 0)
+
   @impl true
   def storage_type, do: :utc_datetime_usec
 
@@ -17,6 +19,16 @@ defmodule Ash.Type.UtcDatetimeUsec do
   end
 
   @impl true
+  def cast_input(%Date{} = date, constraints) do
+    case DateTime.new(date, @beginning_of_day) do
+      {:ok, value} ->
+        cast_input(value, constraints)
+
+      _ ->
+        {:error, "Date could not be converted to datetime"}
+    end
+  end
+
   def cast_input(value, _) do
     Ecto.Type.cast(:utc_datetime_usec, value)
   end