protected override Expression VisitMember(MemberExpression m)
{
var expression = Visit(m.Expression);
if (expression is ConstantExpression constExpr)
{
var container = constExpr.Value;
var member = m.Member;
object value = null;
var valueRetrieved = false;
switch (member)
{
case FieldInfo field:
value = field.GetValue(container);
valueRetrieved = true;
break;
case PropertyInfo prop:
value = prop.GetValue(container, null);
valueRetrieved = true;
break;
}
if (valueRetrieved)
{
var dbObject = _dbFactory.BuildConstant(value, true);
_state.ResultStack.Push(dbObject);
return(m);
}
}
var typeInfo = m.Type.GetTypeInfo();
if (m.Expression.Type.IsAnonymouse())
{
var dbRef = (DbReference)_state.ResultStack.Peek();
if (dbRef.RefSelection.ContainsKey(m.Member.Name))
{
var dbObj = dbRef.RefSelection[m.Member.Name];
// pop out the dbRef from the stack, it was the result of
// translate a parameter, and it is not required for following translation
_state.ResultStack.Pop();
_state.ResultStack.Push(dbObj);
return(m);
}
}
if (m.Expression.Type.IsGrouping())
{
var dbRef = (DbReference)_state.ResultStack.Pop();
var dbSelect = dbRef.OwnerSelect;
if (dbSelect.GroupBys.IsSingleKey)
{
var kColumn = dbSelect.GroupBys.Single();
_state.ResultStack.Push(kColumn);
}
else
{
_state.ResultStack.Push(dbRef);
}
return(m);
}
// if the member is a queryable entity, we need to translate it
// into a relation, which means a join
var entityInfo = _infoProvider.FindEntityInfo(m.Type);
if (entityInfo != null)
{
var dbObj = _state.ResultStack.Pop();
var refCol = dbObj as IDbRefColumn;
var fromRef = refCol != null ? refCol.Ref : (DbReference)dbObj;
var fromEntity = _infoProvider.FindEntityInfo(m.Expression.Type);
var relation = fromEntity.GetRelation(m.Member.Name);
var dbJoin = GetOrCreateJoin(relation, fromRef, refCol ?? fromRef.ReferredRefColumn);
// RefColumnAlias is used as alias in case we need to create a ref column for this dbRef
dbJoin.To.RefColumnAlias = m.Member.Name;
if (refCol != null)
{
refCol = _dbFactory.BuildRefColumn(dbJoin.To, m.Member.Name);
if (dbJoin.To.Referee is IDbSelect subSelect)
{
refCol.RefTo = subSelect.Selection.OfType <IDbRefColumn>().Single();
}
_state.ResultStack.Push(refCol);
return(m);
}
_state.ResultStack.Push(relation.IsChildRelation ? dbJoin.To.Referee : dbJoin.To);
return(m);
}
if (typeInfo.Namespace.StartsWith("System"))
{
var dbObj = _state.ResultStack.Pop();
var refCol = dbObj as IDbRefColumn;
var dbRef = refCol != null ? refCol.Ref : (DbReference)dbObj;
var fieldInfo = _infoProvider.FindFieldInfo(m.Member);
var col = _dbFactory.BuildColumn(dbRef, fieldInfo.DbName, fieldInfo.ValType);
_state.ResultStack.Push(col);
// if we create a column whose DbRef is using by a RefColumn
// we need to make sure the column is added to the ref column's owner select
// This normally happen when we are accessing a column from a child relation
refCol = refCol ?? dbRef.ReferredRefColumn;
// if the ref column is not now, and it is referring another ref column
// we need to make sure the column we translated is in the sub select which
// owns the ref column that referred by the current refColumn
refCol?.RefTo?.AddToReferedSelect(_dbFactory, fieldInfo.DbName, fieldInfo.ValType);
return(m);
}
return(base.VisitMember(m));
}