// public static methods
public static AstPipeline Translate(TranslationContext context, MethodCallExpression expression)
{
var method = expression.Method;
var arguments = expression.Arguments;
if (method.IsOneOf(__groupByMethods))
{
var sourceExpression = arguments[0];
var pipeline = ExpressionToPipelineTranslator.Translate(context, sourceExpression);
var sourceSerializer = pipeline.OutputSerializer;
var keySelectorLambda = ExpressionHelper.UnquoteLambda(arguments[1]);
var keySelectorTranslation = ExpressionToAggregationExpressionTranslator.TranslateLambdaBody(context, keySelectorLambda, sourceSerializer, asRoot: true);
var keySerializer = keySelectorTranslation.Serializer;
var(elementAst, elementSerializer) = TranslateElement(context, method, arguments, sourceSerializer);
var groupingSerializer = IGroupingSerializer.Create(keySerializer, elementSerializer);
pipeline = pipeline.AddStages(
groupingSerializer,
AstStage.Group(
id: keySelectorTranslation.Ast,
fields: AstExpression.AccumulatorField("_elements", AstAccumulatorOperator.Push, elementAst)));
if (method.IsOneOf(__groupByWithResultSelectorMethods))
{
pipeline = TranslateResultSelector(context, pipeline, arguments, keySerializer, elementSerializer);
}
return(pipeline);
}
throw new ExpressionNotSupportedException(expression);
}
public void PipelineStageDefinitionBuilderGroupForLinq3_with_expressions_should_work_with_LINQ3()
{
var(groupStageDefinition, projectStageDefinition) = PipelineStageDefinitionBuilder.GroupForLinq3((BsonDocument x) => 1, x => new { Count = x.Count() });
var groupStage = Linq3TestHelpers.Render(groupStageDefinition, BsonDocumentSerializer.Instance, LinqProvider.V3);
var groupingSerializer = new IGroupingSerializer <int, BsonDocument>(new Int32Serializer(), BsonDocumentSerializer.Instance);
var projectStage = Linq3TestHelpers.Render(projectStageDefinition, groupingSerializer, LinqProvider.V3);
var expectedStages = new[]
{
"{ $group : { _id : 1, __agg0 : { $sum : 1 } } }",
"{ $project : { Count : '$__agg0', _id : 0 } }"
};
Linq3TestHelpers.AssertStages(new[] { groupStage, projectStage }, expectedStages);
}
