private static Expression BindResult<TSource,TResult>(
PipelineBindingContext bindingContext,
Expression<Func<TSource, TResult>> expression,
IBsonSerializer<TSource> sourceSerializer)
{
var parameterExpression = new DocumentExpression(sourceSerializer);
bindingContext.AddExpressionMapping(expression.Parameters[0], parameterExpression);
var node = PartialEvaluator.Evaluate(expression.Body);
node = Transformer.Transform(node);
node = bindingContext.Bind(node);
var resultSerializer = bindingContext.GetSerializer(node.Type, node);
return new AggregateExpressionExpression(node, resultSerializer);
}
private static Expression BindKeySelector <TKey, TDocument>(PipelineBindingContext bindingContext, Expression <Func <TDocument, TKey> > keySelector, IBsonSerializer <TDocument> parameterSerializer)
{
var parameterExpression = new DocumentExpression(parameterSerializer);
bindingContext.AddExpressionMapping(keySelector.Parameters[0], parameterExpression);
var node = PartialEvaluator.Evaluate(keySelector.Body);
node = Transformer.Transform(node);
node = bindingContext.Bind(node);
var keySerializer = bindingContext.GetSerializer(node.Type, node);
return(new GroupingKeyExpression(node, keySerializer));
}
public static RenderedProjectionDefinition <TResult> Translate <TDocument, TResult>(Expression <Func <TDocument, TResult> > projector, IBsonSerializer <TDocument> parameterSerializer, IBsonSerializerRegistry serializerRegistry)
{
var bindingContext = new PipelineBindingContext(serializerRegistry);
var parameterExpression = new DocumentExpression(parameterSerializer);
bindingContext.AddExpressionMapping(projector.Parameters[0], parameterExpression);
var node = PartialEvaluator.Evaluate(projector.Body);
node = Transformer.Transform(node);
node = bindingContext.Bind(node);
var projectionSerializer = bindingContext.GetSerializer(node.Type, node);
var projection = TranslateProject(node);
return(new RenderedProjectionDefinition <TResult>(projection, (IBsonSerializer <TResult>)projectionSerializer));
}
public static RenderedProjectionDefinition <TResult> Translate <TKey, TDocument, TResult>(Expression <Func <TDocument, TKey> > idProjector, Expression <Func <IGrouping <TKey, TDocument>, TResult> > groupProjector, IBsonSerializer <TDocument> parameterSerializer, IBsonSerializerRegistry serializerRegistry)
{
var bindingContext = new PipelineBindingContext(serializerRegistry);
var keySelector = BindKeySelector(bindingContext, idProjector, parameterSerializer);
var boundGroupExpression = BindGroup(bindingContext, groupProjector, parameterSerializer, keySelector);
var projectionSerializer = bindingContext.GetSerializer(boundGroupExpression.Type, boundGroupExpression);
var projection = AggregateLanguageTranslator.Translate(boundGroupExpression).AsBsonDocument;
// must have an "_id" in a group document
if (!projection.Contains("_id"))
{
var idProjection = AggregateLanguageTranslator.Translate(keySelector);
projection.InsertAt(0, new BsonElement("_id", idProjection));
}
return(new RenderedProjectionDefinition <TResult>(projection, (IBsonSerializer <TResult>)projectionSerializer));
}