Cosmos: strip implicit casts to allow vector search over arrays

Fixes #34402

src/EFCore.Cosmos/Query/Internal/CosmosSqlTranslatingExpressionVisitor.cs

@@ -820,13 +820,18 @@ protected override Expression VisitUnary(UnaryExpression unaryExpression)
             ExpressionType.Negate or ExpressionType.NegateChecked
                 => sqlExpressionFactory.Negate(sqlOperand!),
 
-            ExpressionType.Convert or ExpressionType.ConvertChecked
-                when operand.Type.IsInterface
-                && unaryExpression.Type.GetInterfaces().Any(e => e == operand.Type)
+            // Convert nodes can be an explicit user gesture in the query, or they may get introduced by the compiler (e.g. when a Child is
+            // passed as an argument for a parameter of type Parent). The latter type should generally get stripped out as a pure C#/LINQ
+            // artifact that shouldn't affect translation, but the latter may be an indication from the user that they want to apply a
+            // type change.
+            ExpressionType.Convert or ExpressionType.ConvertChecked or ExpressionType.TypeAs
+                when operand.Type.IsInterface && unaryExpression.Type.GetInterfaces().Any(e => e == operand.Type)
+                // We strip out implicit conversions, e.g. float[] -> ReadOnlyMemory<float> (for vector search)
+                || unaryExpression.Method is { IsSpecialName: true, Name: "op_Implicit"}
                 || unaryExpression.Type.UnwrapNullableType() == operand.Type
                 || unaryExpression.Type.UnwrapNullableType() == typeof(Enum)
                 // Object convert needs to be converted to explicit cast when mismatching types
-                // But we let is pass here since we don't have explicit cast mechanism here and in some cases object convert is due to value types
+                // But we let it pass here since we don't have explicit cast mechanism here and in some cases object convert is due to value types
                 || unaryExpression.Type == typeof(object)
                 => sqlOperand!,
 

test/EFCore.Cosmos.FunctionalTests/VectorSearchCosmosTest.cs

@@ -99,16 +99,19 @@ public virtual async Task Query_for_vector_distance_bytes_array()
         await using var context = CreateContext();
         var inputVector = new byte[] { 2, 1, 4, 3, 5, 2, 5, 7, 3, 1 };
 
-        // See Issue #34402
-        await Assert.ThrowsAsync<InvalidOperationException>(
-            () => context.Set<Book>().Select(e => EF.Functions.VectorDistance(e.BytesArray, inputVector)).ToListAsync());
+        var booksFromStore = await context
+            .Set<Book>()
+            .Select(e => EF.Functions.VectorDistance(e.BytesArray, inputVector))
+            .ToListAsync();
 
-        // Assert.Equal(3, booksFromStore.Count);
-        // Assert.All(booksFromStore, s => Assert.NotEqual(0.0, s));
+        Assert.Equal(3, booksFromStore.Count);
+        Assert.All(booksFromStore, s => Assert.NotEqual(0.0, s));
 
         AssertSql(
             """
-SELECT VALUE c["BytesArray"]
+@__inputVector_1='[2,1,4,3,5,2,5,7,3,1]'
+
+SELECT VALUE VectorDistance(c["Bytes"], @__inputVector_1, false, {'distanceFunction':'cosine', 'dataType':'uint8'})
 FROM root c
 """);
     }
@@ -119,17 +122,20 @@ public virtual async Task Query_for_vector_distance_singles_array()
         await using var context = CreateContext();
         var inputVector = new[] { 0.33f, -0.52f, 0.45f, -0.67f, 0.89f, -0.34f, 0.86f, -0.78f, 0.86f, -0.78f };
 
-        // See Issue #34402
-        await Assert.ThrowsAsync<InvalidOperationException>(
-            () => context.Set<Book>()
-                .Select(e => EF.Functions.VectorDistance(e.SinglesArray, inputVector, false, DistanceFunction.DotProduct)).ToListAsync());
+        var booksFromStore = await context
+            .Set<Book>()
+            .Select(
+                e => EF.Functions.VectorDistance(e.SinglesArray, inputVector, false, DistanceFunction.DotProduct))
+            .ToListAsync();
 
-        // Assert.Equal(3, booksFromStore.Count);
-        // Assert.All(booksFromStore, s => Assert.NotEqual(0.0, s));
+        Assert.Equal(3, booksFromStore.Count);
+        Assert.All(booksFromStore, s => Assert.NotEqual(0.0, s));
 
         AssertSql(
             """
-SELECT VALUE c["SinglesArray"]
+@__inputVector_1='[0.33,-0.52,0.45,-0.67,0.89,-0.34,0.86,-0.78,0.86,-0.78]'
+
+SELECT VALUE VectorDistance(c["Singles"], @__inputVector_1, false, {'distanceFunction':'dotproduct', 'dataType':'float32'})
 FROM root c
 """);
     }
@@ -207,14 +213,20 @@ public virtual async Task Vector_distance_bytes_array_in_OrderBy()
         await using var context = CreateContext();
         var inputVector = new byte[] { 2, 1, 4, 6, 5, 2, 5, 7, 3, 1 };
 
-        // See Issue #34402
-        await Assert.ThrowsAsync<InvalidOperationException>(
-            () => context.Set<Book>().OrderBy(e => EF.Functions.VectorDistance(e.BytesArray, inputVector)).ToListAsync());
-
-        // Assert.Equal(3, booksFromStore.Count);
+        var booksFromStore = await context
+            .Set<Book>()
+            .OrderBy(e => EF.Functions.VectorDistance(e.BytesArray, inputVector))
+            .ToListAsync();
 
+        Assert.Equal(3, booksFromStore.Count);
         AssertSql(
-);
+            """
+@__p_1='[2,1,4,6,5,2,5,7,3,1]'
+
+SELECT VALUE c
+FROM root c
+ORDER BY VectorDistance(c["Bytes"], @__p_1, false, {'distanceFunction':'cosine', 'dataType':'uint8'})
+""");
     }
 
     [ConditionalFact]
@@ -223,13 +235,20 @@ public virtual async Task Vector_distance_singles_array_in_OrderBy()
         await using var context = CreateContext();
         var inputVector = new[] { 0.33f, -0.52f, 0.45f, -0.67f, 0.89f, -0.34f, 0.86f, -0.78f };
 
-        // See Issue #34402
-        await Assert.ThrowsAsync<InvalidOperationException>(
-            () => context.Set<Book>().OrderBy(e => EF.Functions.VectorDistance(e.SinglesArray, inputVector)).ToListAsync());
+        var booksFromStore = await context
+            .Set<Book>()
+            .OrderBy(e => EF.Functions.VectorDistance(e.SinglesArray, inputVector))
+            .ToListAsync();
 
-        // Assert.Equal(3, booksFromStore.Count);
+        Assert.Equal(3, booksFromStore.Count);
+        AssertSql(
+            """
+@__p_1='[0.33,-0.52,0.45,-0.67,0.89,-0.34,0.86,-0.78]'
 
-        AssertSql();
+SELECT VALUE c
+FROM root c
+ORDER BY VectorDistance(c["Singles"], @__p_1, false, {'distanceFunction':'cosine', 'dataType':'float32'})
+""");
     }
 
     [ConditionalFact]