protected static Expression BindPredicate(ProjectionExpression projection, ProjectionBindingContext context, Expression source, Expression argument)
{
// this is actually a predicate that needs to be rendered as a WhereExpression
var lambda = ExtensionExpressionVisitor.GetLambda(argument);
var binder = new AccumulatorBinder(context.GroupMap, context.SerializerRegistry);
binder.RegisterParameterReplacement(lambda.Parameters[0], projection.Projector);
var predicate = binder.Bind(lambda.Body);
source = new WhereExpression(
source,
predicate);
return source;
}
protected internal override Expression VisitWhere(WhereExpression node)
{
var sourceWhere = node.Source as WhereExpression;
if (sourceWhere != null)
{
var source = sourceWhere.Source;
var newWhere = new WhereExpression(
source,
node.ItemName,
Expression.And(
sourceWhere.Predicate,
node.Predicate));
return base.Visit(newWhere);
}
return node;
}
protected internal virtual Expression VisitWhere(WhereExpression node)
{
return(node.Update(
Visit(node.Source),
Visit(node.Predicate)));
}
private void TranslateWhere(WhereExpression node)
{
Translate(node.Source);
var predicateValue = PredicateTranslator.Translate(node.Predicate, _serializerRegistry);
_stages.Add(new BsonDocument("$match", predicateValue));
}
protected internal virtual Expression VisitWhere(WhereExpression node)
{
return node.Update(
Visit(node.Source),
Visit(node.Predicate));
}
private BsonValue TranslateWhere(WhereExpression node)
{
var inputValue = TranslateValue(node.Source);
var condValue = TranslateValue(FieldNamePrefixer.Prefix(node.Predicate, "$" + node.ItemName));
return new BsonDocument("$filter", new BsonDocument
{
{ "input", inputValue },
{ "as", node.ItemName },
{ "cond", condValue }
});
}
private void VisitWhere(WhereExpression node)
{
Visit(node.Source);
var renderedPredicate = PredicateTranslator.Translate(node.Predicate, _serializerRegistry);
_stages.Add(new BsonDocument("$match", renderedPredicate));
}
