protected override Expression VisitMemberAccess(MemberExpression m)
{
Expression source = this.Visit(m.Expression);
if (this.mapping.IsRelationship(m.Member))
{
ProjectionExpression projection = (ProjectionExpression)this.Visit(this.mapping.GetMemberExpression(source, m.Member));
if (this.currentFrom != null && this.mapping.IsSingletonRelationship(m.Member))
{
// convert singleton associations directly to OUTER APPLY
projection = projection.AddOuterJoinTest();
Expression newFrom = new JoinExpression(JoinType.OuterApply, this.currentFrom, projection.Source, null);
this.currentFrom = newFrom;
return(projection.Projector);
}
return(projection);
}
else
{
Expression result = QueryBinder.BindMember(source, m.Member);
MemberExpression mex = result as MemberExpression;
if (mex != null && mex.Member == m.Member && mex.Expression == m.Expression)
{
return(m);
}
return(result);
}
}
protected virtual Expression BindSelectMany(Type resultType, Expression source,
LambdaExpression collectionSelector, LambdaExpression resultSelector)
{
ProjectionExpression projection = VisitSequence(source);
map[collectionSelector.Parameters[0]] = projection.Projector;
Expression collection = collectionSelector.Body;
// check for DefaultIfEmpty
bool defaultIfEmpty = false;
MethodCallExpression mcs = collection as MethodCallExpression;
if (mcs != null && mcs.Method.Name == "DefaultIfEmpty" && mcs.Arguments.Count == 1 &&
(mcs.Method.DeclaringType == typeof(Queryable) || mcs.Method.DeclaringType == typeof(Enumerable)))
{
collection = mcs.Arguments[0];
defaultIfEmpty = true;
}
ProjectionExpression collectionProjection = VisitSequence(collection);
bool isTable = collectionProjection.Source.From is TableExpression;
JoinType joinType = isTable
? JoinType.CrossJoin
: defaultIfEmpty ? JoinType.OuterApply : JoinType.CrossApply;
if (joinType == JoinType.OuterApply)
{
collectionProjection = collectionProjection.AddOuterJoinTest();
}
JoinExpression join = new JoinExpression(joinType, projection.Source, collectionProjection.Source, null);
var alias = GetNextAlias();
ProjectedColumns pc;
if (resultSelector == null)
{
pc = ProjectColumns(collectionProjection.Projector, alias, projection.Source.Alias,
collectionProjection.Source.Alias);
}
else
{
map[resultSelector.Parameters[0]] = projection.Projector;
map[resultSelector.Parameters[1]] = collectionProjection.Projector;
Expression result = Visit(resultSelector.Body);
pc = ProjectColumns(result, alias, projection.Source.Alias, collectionProjection.Source.Alias);
}
return(new ProjectionExpression(
new SelectExpression(alias, pc.Columns, join, null),
pc.Projector
));
}
