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CSHARP-4878: Implement Repeat in nested LINQ expressions.
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‎src/MongoDB.Driver/Linq/Linq3Implementation/Translators/ExpressionToAggregationExpressionTranslators/MethodCallExpressionToAggregationExpressionTranslator.cs‎

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@@ -68,6 +68,7 @@ public static AggregationExpression Translate(TranslationContext context, Method
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case "Push": return PushMethodToAggregationExpressionTranslator.Translate(context, expression);
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case "Range": return RangeMethodToAggregationExpressionTranslator.Translate(context, expression);
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case "Rank": return RankMethodToAggregationExpressionTranslator.Translate(context, expression);
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case "Repeat": return RepeatMethodToAggregationExpressionTranslator.Translate(context, expression);
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case "Reverse": return ReverseMethodToAggregationExpressionTranslator.Translate(context, expression);
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case "Round": return RoundMethodToAggregationExpressionTranslator.Translate(context, expression);
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case "Select": return SelectMethodToAggregationExpressionTranslator.Translate(context, expression);

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

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/* Copyright 2010-present MongoDB Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System.Linq.Expressions;
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using System.Reflection;
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using MongoDB.Driver.Linq.Linq3Implementation.Ast.Expressions;
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using MongoDB.Driver.Linq.Linq3Implementation.Misc;
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using MongoDB.Driver.Linq.Linq3Implementation.Reflection;
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using MongoDB.Driver.Linq.Linq3Implementation.Serializers;
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namespace MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.MethodTranslators
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{
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internal static class RepeatMethodToAggregationExpressionTranslator
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{
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public static AggregationExpression Translate(TranslationContext context, MethodCallExpression expression)
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{
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var method = expression.Method;
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var arguments = expression.Arguments;
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if (method.Is(EnumerableMethod.Repeat))
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{
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var elementExpression = arguments[0];
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var countExpression = arguments[1];
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var elementTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, elementExpression);
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var countTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, countExpression);
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var (elementVarBinding, elementAst) = AstExpression.UseVarIfNotSimple("element", elementTranslation.Ast);
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var ast = AstExpression.Let(
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var: elementVarBinding,
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@in: AstExpression.Map(
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input: AstExpression.Range(0, countTranslation.Ast),
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@as: AstExpression.Var("i"),
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@in: elementAst));
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var resultSerializer = IEnumerableSerializer.Create(elementTranslation.Serializer);
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return new AggregationExpression(expression, ast, resultSerializer);
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}
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throw new ExpressionNotSupportedException(expression);
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}
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}
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}

‎tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/Jira/CSharp4878Tests.cs‎

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/* Copyright 2010-present MongoDB Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System.Linq;
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using FluentAssertions;
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using Xunit;
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namespace MongoDB.Driver.Tests.Linq.Linq3Implementation.Jira
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{
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public class CSharp4878Tests : Linq3IntegrationTest
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{
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[Fact]
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public void Repeat_with_constant_and_constant_should_work()
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{
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var collection = GetCollection();
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var queryable = collection.AsQueryable().Select(x => Enumerable.Repeat(2, 3));
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var stages = Translate(collection, queryable);
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AssertStages(stages, "{ $project : { _v : [2, 2, 2], _id : 0 } }");
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var result = queryable.First();
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result.Should().Equal(2, 2, 2);
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}
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[Fact]
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public void Repeat_with_constant_and_expression_should_work()
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{
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var collection = GetCollection();
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var queryable = collection.AsQueryable().Select(x => Enumerable.Repeat(2, x.Y));
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var stages = Translate(collection, queryable);
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AssertStages(stages, "{ $project : { _v : { $map : { input : { $range : [0, '$Y'] }, as : 'i', in : 2 } }, _id : 0 } }");
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var result = queryable.First();
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result.Should().Equal(2, 2, 2);
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}
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[Fact]
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public void Repeat_with_expression_and_constant_should_work()
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{
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var collection = GetCollection();
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var queryable = collection.AsQueryable().Select(x => Enumerable.Repeat(x.X, 3));
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var stages = Translate(collection, queryable);
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AssertStages(stages, "{ $project : { _v : { $map : { input : { $range : [0, 3] }, as : 'i', in : '$X' } }, _id : 0 } }");
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var result = queryable.First();
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result.Should().Equal(2, 2, 2);
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}
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[Fact]
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public void Repeat_with_expression_and_expression_should_work()
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{
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var collection = GetCollection();
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var queryable = collection.AsQueryable().Select(x => Enumerable.Repeat(x.X, x.Y));
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var stages = Translate(collection, queryable);
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AssertStages(stages, "{ $project : { _v : { $map : { input : { $range : [0, '$Y'] }, as : 'i', in : '$X' } }, _id : 0 } }");
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var result = queryable.First();
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result.Should().Equal(2, 2, 2);
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}
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private IMongoCollection<C> GetCollection()
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{
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var collection = GetCollection<C>("test");
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CreateCollection(
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collection,
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new C { Id = 1, X = 2, Y = 3 });
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return collection;
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}
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private class C
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{
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public int Id { get; set; }
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public int X { get; set; }
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public int Y { get; set; }
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}
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}
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}

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