From d447950255e39a00a16466d7fe6e6d42a7c91eea Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Tue, 11 Aug 2020 17:59:44 +0800
Subject: Post list modified since now consider username change. And make all
 datetime utc.

---
 Timeline/Entities/UtcDateAnnotation.cs | 44 ++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Timeline/Entities/UtcDateAnnotation.cs

(limited to 'Timeline/Entities/UtcDateAnnotation.cs')

diff --git a/Timeline/Entities/UtcDateAnnotation.cs b/Timeline/Entities/UtcDateAnnotation.cs
new file mode 100644
index 00000000..6600e701
--- /dev/null
+++ b/Timeline/Entities/UtcDateAnnotation.cs
@@ -0,0 +1,44 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using System;
+
+namespace Timeline.Entities
+{
+    // Copied from https://github.com/dotnet/efcore/issues/4711#issuecomment-589842988
+    public static class UtcDateAnnotation
+    {
+        private const string IsUtcAnnotation = "IsUtc";
+        private static readonly ValueConverter<DateTime, DateTime> UtcConverter =
+            new ValueConverter<DateTime, DateTime>(v => v, v => DateTime.SpecifyKind(v, DateTimeKind.Utc));
+
+        public static PropertyBuilder<TProperty> IsUtc<TProperty>(this PropertyBuilder<TProperty> builder, bool isUtc = true) =>
+            builder.HasAnnotation(IsUtcAnnotation, isUtc);
+
+        public static bool IsUtc(this IMutableProperty property) =>
+            ((bool?)property.FindAnnotation(IsUtcAnnotation)?.Value) ?? true;
+
+        /// <summary>
+        /// Make sure this is called after configuring all your entities.
+        /// </summary>
+        public static void ApplyUtcDateTimeConverter(this ModelBuilder builder)
+        {
+            foreach (var entityType in builder.Model.GetEntityTypes())
+            {
+                foreach (var property in entityType.GetProperties())
+                {
+                    if (!property.IsUtc())
+                    {
+                        continue;
+                    }
+
+                    if (property.ClrType == typeof(DateTime))
+                    {
+                        property.SetValueConverter(UtcConverter);
+                    }
+                }
+            }
+        }
+    }
+}
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