Implement average aggregation for decimal in SQLite

Contributes to dotnet#19635
ranma42 · May 15, 2024 · 50b76b6 · 50b76b6
1 parent 5ffdda0
commit 50b76b6
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Showing 2 changed files with 19 additions and 3 deletions.
diff --git a/src/EFCore.Sqlite.Core/Query/Internal/SqliteQueryableAggregateMethodTranslator.cs b/src/EFCore.Sqlite.Core/Query/Internal/SqliteQueryableAggregateMethodTranslator.cs
@@ -53,9 +53,14 @@ public SqliteQueryableAggregateMethodTranslator(ISqlExpressionFactory sqlExpress
                     var averageArgumentType = GetProviderType(averageSqlExpression);
                     if (averageArgumentType == typeof(decimal))
                     {
-                        throw new NotSupportedException(
-                            SqliteStrings.AggregateOperationNotSupported(
-                                nameof(Queryable.Average), averageArgumentType.ShortDisplayName()));
+                        averageSqlExpression = CombineTerms(source, averageSqlExpression);
+                        return _sqlExpressionFactory.Function(
+                            "ef_avg",
+                            [averageSqlExpression],
+                            nullable: true,
+                            argumentsPropagateNullability: [false],
+                            averageSqlExpression.Type,
+                            averageSqlExpression.TypeMapping);
                     }
 
                     break;

diff --git a/src/EFCore.Sqlite.Core/Storage/Internal/SqliteRelationalConnection.cs b/src/EFCore.Sqlite.Core/Storage/Internal/SqliteRelationalConnection.cs
@@ -142,6 +142,17 @@ private void InitializeDbConnection(DbConnection connection)
                 name: "ef_negate",
                 (decimal? m) => -m,
                 isDeterministic: true);
+
+            sqliteConnection.CreateAggregate(
+                "ef_avg",
+                seed: (0m, 0ul),
+                ((decimal sum, ulong count) acc, decimal? value) => value is null
+                    ? acc
+                    : (acc.sum + value.Value, acc.count + 1),
+                ((decimal sum, ulong count) acc) => acc.count == 0
+                    ? default(decimal?)
+                    : acc.sum / acc.count,
+                isDeterministic: true);
         }
         else
         {