CSHARP-5656: Support Aggregation Operator to generate random object ids

src/MongoDB.Driver/Core/Misc/Feature.cs

@@ -52,6 +52,7 @@ public class Feature
         private static readonly Feature __convertOperatorStringToObjectOrArray = new Feature("ConvertOperatorStringToObjectOrArray", WireVersion.Server83);
         private static readonly Feature __createIndexCommitQuorum = new Feature("CreateIndexCommitQuorum", WireVersion.Server44);
         private static readonly Feature __createIndexesUsingInsertOperations = new Feature("CreateIndexesUsingInsertOperations", WireVersion.Zero, WireVersion.Server42);
+        private static readonly Feature __createObjectIdExpression = new Feature("CreateObjectIdExpression", WireVersion.Server83);
         private static readonly Feature __csfleRangeAlgorithm = new Feature("CsfleRangeAlgorithm", WireVersion.Server62);
         private static readonly Feature __csfle2Qev2Lookup = new Feature("csfle2Qev2Lookup", WireVersion.Server81);
         private static readonly Feature __csfle2Qev2RangeAlgorithm = new Feature("csfle2Qev2RangeAlgorithm", WireVersion.Server80);
@@ -248,6 +249,11 @@ public class Feature
         [Obsolete("This feature was removed in server version 4.2. As such, this property will be removed in a later release.")]
         public static Feature CreateIndexesUsingInsertOperations => __createIndexesUsingInsertOperations;
 
+        /// <summary>
+        /// Represents support for the $createObjectId operator feature.
+        /// </summary>
+        public static Feature CreateObjectIdExpression => __createObjectIdExpression;
+
         /// <summary>
         /// Gets the csfle range algorithm feature.
         /// </summary>

src/MongoDB.Driver/Linq/Linq3Implementation/Ast/AstNodeType.cs

@@ -38,6 +38,7 @@ internal enum AstNodeType
         ConstantExpression,
         ConvertExpression,
         CountStage,
+        CreateObjectIdExpression,
         CurrentOpStage,
         CustomAccumulatorExpression,
         DateAddExpression,

src/MongoDB.Driver/Linq/Linq3Implementation/Ast/Expressions/AstCreateObjectIdExpression.cs

@@ -0,0 +1,30 @@
+/* Copyright 2010-present MongoDB Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using MongoDB.Bson;
+using MongoDB.Driver.Linq.Linq3Implementation.Ast.Visitors;
+
+namespace MongoDB.Driver.Linq.Linq3Implementation.Ast.Expressions;
+
+internal sealed class AstCreateObjectIdExpression : AstExpression
+{
+    public override AstNodeType NodeType => AstNodeType.CreateObjectIdExpression;
+
+    public override AstNode Accept(AstNodeVisitor visitor) =>
+        visitor.VisitCreateObjectIdExpression(this);
+
+    public override BsonValue Render() =>
+        new BsonDocument("$createObjectId", new BsonDocument());
+}

src/MongoDB.Driver/Linq/Linq3Implementation/Ast/Expressions/AstExpression.cs

@@ -443,6 +443,9 @@ public static AstExpression Floor(AstExpression arg)
             return new AstUnaryExpression(AstUnaryOperator.Floor, arg);
         }
 
+        public static AstCreateObjectIdExpression CreateObjectId()
+            => new();
+
         public static AstGetFieldExpression GetField(AstExpression input, AstExpression fieldName)
         {
             return new AstGetFieldExpression(input, fieldName);

src/MongoDB.Driver/Linq/Linq3Implementation/Ast/Visitors/AstNodeVisitor.cs

@@ -244,6 +244,9 @@ public virtual AstNode VisitCustomAccumulatorExpression(AstCustomAccumulatorExpr
             return node.Update(VisitAndConvert(node.InitArgs), VisitAndConvert(node.AccumulateArgs));
         }
 
+        public virtual AstNode VisitCreateObjectIdExpression(AstCreateObjectIdExpression node)
+            => node;
+
         public virtual AstNode VisitDateAddExpression(AstDateAddExpression node)
         {
             return node.Update(VisitAndConvert(node.StartDate), VisitAndConvert(node.Unit), VisitAndConvert(node.Amount), VisitAndConvert(node.Timezone));

src/MongoDB.Driver/Linq/Linq3Implementation/Reflection/MqlMethod.cs

@@ -27,6 +27,7 @@ internal static class MqlMethod
         private static readonly MethodInfo __constantWithRepresentation;
         private static readonly MethodInfo __constantWithSerializer;
         private static readonly MethodInfo __convert;
+        private static readonly MethodInfo __createObjectId;
         private static readonly MethodInfo __dateFromString;
         private static readonly MethodInfo __dateFromStringWithFormat;
         private static readonly MethodInfo __dateFromStringWithFormatAndTimezone;
@@ -53,6 +54,7 @@ static MqlMethod()
             __constantWithRepresentation = ReflectionInfo.Method((object value, BsonType representation) => Mql.Constant(value, representation));
             __constantWithSerializer = ReflectionInfo.Method((object value, IBsonSerializer<object> serializer) => Mql.Constant(value, serializer));
             __convert = ReflectionInfo.Method((object value, ConvertOptions<object> options) => Mql.Convert(value, options));
+            __createObjectId = ReflectionInfo.Method(() => Mql.CreateObjectId());
             __dateFromString = ReflectionInfo.Method((string dateStringl) => Mql.DateFromString(dateStringl));
             __dateFromStringWithFormat = ReflectionInfo.Method((string dateString, string format) => Mql.DateFromString(dateString, format));
             __dateFromStringWithFormatAndTimezone = ReflectionInfo.Method((string dateString, string format, string timezone) => Mql.DateFromString(dateString, format, timezone));
@@ -110,6 +112,7 @@ static MqlMethod()
         public static MethodInfo ConstantWithRepresentation => __constantWithRepresentation;
         public static MethodInfo ConstantWithSerializer => __constantWithSerializer;
         public static MethodInfo Convert => __convert;
+        public static MethodInfo CreateObjectId => __createObjectId;
         public static MethodInfo DateFromString => __dateFromString;
         public static MethodInfo DateFromStringWithFormat => __dateFromStringWithFormat;
         public static MethodInfo DateFromStringWithFormatAndTimezone => __dateFromStringWithFormatAndTimezone;

src/MongoDB.Driver/Linq/Linq3Implementation/Reflection/ReflectionInfo.cs

@@ -16,106 +16,69 @@
 using System;
 using System.Linq.Expressions;
 using System.Reflection;
-using MongoDB.Driver.Linq.Linq3Implementation.Misc;
 
 namespace MongoDB.Driver.Linq.Linq3Implementation.Reflection
 {
     internal static class ReflectionInfo
     {
-        public static ConstructorInfo Constructor<TObject>(Expression<Func<TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<TObject>(Expression<Func<TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, TObject>(Expression<Func<T1, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, TObject>(Expression<Func<T1, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, T2, TObject>(Expression<Func<T1, T2, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, T2, TObject>(Expression<Func<T1, T2, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, T2, T3, TObject>(Expression<Func<T1, T2, T3, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, T2, T3, TObject>(Expression<Func<T1, T2, T3, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, T2, T3, T4, TObject>(Expression<Func<T1, T2, T3, T4, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, T2, T3, T4, TObject>(Expression<Func<T1, T2, T3, T4, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, T2, T3, T4, T5, TObject>(Expression<Func<T1, T2, T3, T4, T5, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, T2, T3, T4, T5, TObject>(Expression<Func<T1, T2, T3, T4, T5, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, T2, T3, T4, T5, T6, TObject>(Expression<Func<T1, T2, T3, T4, T5, T6, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, T2, T3, T4, T5, T6, TObject>(Expression<Func<T1, T2, T3, T4, T5, T6, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static ConstructorInfo Constructor<T1, T2, T3, T4, T5, T6, T7, TObject>(Expression<Func<T1, T2, T3, T4, T5, T6, T7, TObject>> lambda)
-        {
-            return ExtractConstructorInfoFromLambda(lambda);
-        }
+        public static ConstructorInfo Constructor<T1, T2, T3, T4, T5, T6, T7, TObject>(Expression<Func<T1, T2, T3, T4, T5, T6, T7, TObject>> lambda) =>
+            ExtractConstructorInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, TResult>(Expression<Func<T1, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<TResult>(Expression<Func<TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, TResult>(Expression<Func<T1, T2, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, TResult>(Expression<Func<T1, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, T3, TResult>(Expression<Func<T1, T2, T3, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, TResult>(Expression<Func<T1, T2, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, T3, T4, TResult>(Expression<Func<T1, T2, T3, T4, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, T3, TResult>(Expression<Func<T1, T2, T3, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, T3, T4, T5, TResult>(Expression<Func<T1, T2, T3, T4, T5, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, T3, T4, TResult>(Expression<Func<T1, T2, T3, T4, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, T3, T4, T5, T6, TResult>(Expression<Func<T1, T2, T3, T4, T5, T6, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, T3, T4, T5, TResult>(Expression<Func<T1, T2, T3, T4, T5, TResult>> lambda) => ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, T3, T4, T5, T6, T7, TResult>(Expression<Func<T1, T2, T3, T4, T5, T6, T7, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, T3, T4, T5, T6, TResult>(Expression<Func<T1, T2, T3, T4, T5, T6, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo Method<T1, T2, T3, T4, T5, T6, T7, T8, TResult>(Expression<Func<T1, T2, T3, T4, T5, T6, T7, T8, TResult>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, T3, T4, T5, T6, T7, TResult>(Expression<Func<T1, T2, T3, T4, T5, T6, T7, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static PropertyInfo Property<TObject, TProperty>(Expression<Func<TObject, TProperty>> lambda)
-        {
-            return ExtractPropertyInfoFromLambda(lambda);
-        }
+        public static MethodInfo Method<T1, T2, T3, T4, T5, T6, T7, T8, TResult>(Expression<Func<T1, T2, T3, T4, T5, T6, T7, T8, TResult>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
 
-        public static MethodInfo IndexerGet<TObject, TIndex, TValue>(Expression<Func<TObject, TIndex, TValue>> lambda)
-        {
-            return ExtractMethodInfoFromLambda(lambda);
-        }
+        public static PropertyInfo Property<TObject, TProperty>(Expression<Func<TObject, TProperty>> lambda) =>
+            ExtractPropertyInfoFromLambda(lambda);
 
-        public static MethodInfo IndexerSet<TObject, TIndex, TValue>(Expression<Func<TObject, TIndex, TValue>> lambda)
-        {
-            return ExtractIndexerSetMethodInfoFromLambda(lambda);
-        }
+        public static MethodInfo IndexerGet<TObject, TIndex, TValue>(Expression<Func<TObject, TIndex, TValue>> lambda) =>
+            ExtractMethodInfoFromLambda(lambda);
+
+        public static MethodInfo IndexerSet<TObject, TIndex, TValue>(Expression<Func<TObject, TIndex, TValue>> lambda) =>
+            ExtractIndexerSetMethodInfoFromLambda(lambda);
 
         // private static methods
         private static ConstructorInfo ExtractConstructorInfoFromLambda(LambdaExpression lambda)

src/MongoDB.Driver/Linq/Linq3Implementation/SerializerFinders/SerializerFinderVisitMethodCall.cs

@@ -100,6 +100,7 @@ void DeduceMethodCallSerializers()
                 case "ContainsValue": DeduceContainsValueMethodSerializers(); break;
                 case "Convert": DeduceConvertMethodSerializers(); break;
                 case "Create": DeduceCreateMethodSerializers(); break;
+                case "CreateObjectId": DeduceCreateObjectIdMethodSerializers(); break;
                 case "DateFromString": DeduceDateFromStringMethodSerializers(); break;
                 case "DefaultIfEmpty": DeduceDefaultIfEmptyMethodSerializers(); break;
                 case "DegreesToRadians": DeduceDegreesToRadiansMethodSerializers(); break;
@@ -1373,6 +1374,21 @@ void DeduceFieldMethodSerializers()
             }
         }
 
+        void DeduceCreateObjectIdMethodSerializers()
+        {
+            if (method.Is(MqlMethod.CreateObjectId))
+            {
+                if (IsNotKnown(node))
+                {
+                    DeduceSerializer(node, ObjectIdSerializer.Instance);
+                }
+            }
+            else
+            {
+                DeduceUnknownMethodSerializer();
+            }
+        }
+
         void DeduceFirstOrLastOrSingleMethodsSerializers()
         {
             if (method.IsOneOf(EnumerableOrQueryableMethod.FirstOrLastOrSingleOverloads))

src/MongoDB.Driver/Linq/Linq3Implementation/Translators/ExpressionToAggregationExpressionTranslators/MethodCallExpressionToAggregationExpressionTranslator.cs

@@ -42,6 +42,7 @@ public static TranslatedExpression Translate(TranslationContext context, MethodC
                 case "CovariancePopulation": return CovariancePopulationMethodToAggregationExpressionTranslator.Translate(context, expression);
                 case "CovarianceSample": return CovarianceSampleMethodToAggregationExpressionTranslator.Translate(context, expression);
                 case "Create": return CreateMethodToAggregationExpressionTranslator.Translate(context, expression);
+                case "CreateObjectId": return CreateObjectIdMethodToAggregationExpressionTranslator.Translate(context, expression);
                 case "DateFromString": return DateFromStringMethodToAggregationExpressionTranslator.Translate(context, expression);
                 case "DefaultIfEmpty": return DefaultIfEmptyMethodToAggregationExpressionTranslator.Translate(context, expression);
                 case "DenseRank": return DenseRankMethodToAggregationExpressionTranslator.Translate(context, expression);

src/MongoDB.Driver/Linq/Linq3Implementation/Translators/ExpressionToAggregationExpressionTranslators/MethodTranslators/CreateObjectIdMethodToAggregationExpressionTranslator.cs

@@ -0,0 +1,38 @@
+/* Copyright 2010-present MongoDB Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.Linq.Expressions;
+using MongoDB.Driver.Linq.Linq3Implementation.Ast.Expressions;
+using MongoDB.Driver.Linq.Linq3Implementation.Misc;
+using MongoDB.Driver.Linq.Linq3Implementation.Reflection;
+
+namespace MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.MethodTranslators;
+
+internal static class CreateObjectIdMethodToAggregationExpressionTranslator
+{
+    public static TranslatedExpression Translate(TranslationContext context, MethodCallExpression expression)
+    {
+        var method = expression.Method;
+
+        if (method.Is(MqlMethod.CreateObjectId))
+        {
+            var ast = AstExpression.CreateObjectId();
+            var serializer = context.GetSerializer(expression);
+            return new TranslatedExpression(expression, ast, serializer);
+        }
+
+        throw new ExpressionNotSupportedException(expression);
+    }
+}

src/MongoDB.Driver/Mql.cs

@@ -64,6 +64,13 @@ public static TTo Convert<TFrom, TTo>(TFrom value, ConvertOptions<TTo> options)
             throw CustomLinqExtensionMethodHelper.CreateNotSupportedException();
         }
 
+        /// <summary>
+        /// Creates a new unique ObjectId using the $createObjectId aggregation operator.
+        /// </summary>
+        /// <returns>A ObjectId.</returns>
+        public static ObjectId CreateObjectId() =>
+            throw CustomLinqExtensionMethodHelper.CreateNotSupportedException();
+
         /// <summary>
         /// Converts a string to a DateTime using the $dateFromString aggregation operator.
         /// </summary>