protected override Expression VisitMember(MemberExpression memberExpression)
{
var newExpression = Visit(memberExpression.Expression);
var boundProperty = TryBindProperty(memberExpression, newExpression, memberExpression.Member.Name);
var result = boundProperty ?? memberExpression.Update(newExpression);
// add null safety when accessing property of optional navigation
// we don't need to do it for collections (i.e. collection.Count) because they will be converted into subqueries anyway
if (boundProperty == null &&
newExpression is NavigationBindingExpression navigationBindingExpression &&
navigationBindingExpression.NavigationTreeNode.Optional &&
navigationBindingExpression.NavigationTreeNode.Navigation?.IsCollection() != true)
{
var nullProtection = new NullConditionalExpression(newExpression, result);
if (nullProtection.Type == result.Type)
{
return(nullProtection);
}
result = Expression.Convert(nullProtection, memberExpression.Type);
}
return(result);
}
private void VisitNullConditionalExpression(NullConditionalExpression nullConditionalExpression)
{
if (nullConditionalExpression.AccessOperation is MemberExpression memberExpression)
{
Visit(nullConditionalExpression.Caller);
_stringBuilder.Append("?." + memberExpression.Member.Name);
}
else if (nullConditionalExpression.AccessOperation is MethodCallExpression methodCallExpression)
{
if (methodCallExpression.Object != null)
{
Visit(nullConditionalExpression.Caller);
_stringBuilder.Append("?." + methodCallExpression.Method.Name + "(");
VisitArguments(methodCallExpression.Arguments, s => _stringBuilder.Append(s));
_stringBuilder.Append(")");
}
var method = methodCallExpression.Method;
_stringBuilder.Append(method.DeclaringType?.Name + "." + method.Name + "(?");
Visit(nullConditionalExpression.Caller);
_stringBuilder.Append("?, ");
VisitArguments(methodCallExpression.Arguments.Skip(1).ToList(), s => _stringBuilder.Append(s));
_stringBuilder.Append(")");
}
else
{
_stringBuilder.Append("?");
Visit(nullConditionalExpression.AccessOperation);
_stringBuilder.Append("?");
}
}
private static Expression BuildCollectionAccessorExpression(
ParameterExpression parameter,
IEnumerable <IPropertyBase> navigations)
{
Expression result = parameter;
Expression memberExpression = parameter;
foreach (var navigation in navigations)
{
memberExpression = memberExpression.MakeMemberAccess(navigation.GetIdentifyingMemberInfo());
result = new NullConditionalExpression(result, memberExpression);
}
return(result);
}
private static void ApplyParentOrderings(
IEnumerable <Ordering> parentOrderings,
QueryModel queryModel,
QuerySourceMapping querySourceMapping,
bool reverseOrdering)
{
var orderByClause = queryModel.BodyClauses.OfType <OrderByClause>().LastOrDefault();
if (orderByClause == null)
{
queryModel.BodyClauses.Add(orderByClause = new OrderByClause());
}
foreach (var ordering in parentOrderings)
{
var newExpression
= CloningExpressionVisitor
.AdjustExpressionAfterCloning(ordering.Expression, querySourceMapping);
if (newExpression is MethodCallExpression methodCallExpression &&
methodCallExpression.Method.IsEFPropertyMethod())
{
newExpression
= new NullConditionalExpression(
methodCallExpression.Arguments[0],
methodCallExpression.Arguments[0],
methodCallExpression);
}
orderByClause.Orderings
.Add(new Ordering(newExpression, ordering.OrderingDirection));
}
if (reverseOrdering)
{
foreach (var ordering in orderByClause.Orderings)
{
ordering.OrderingDirection
= ordering.OrderingDirection == OrderingDirection.Asc
? OrderingDirection.Desc
: OrderingDirection.Asc;
}
}
}
