I try sort my queryable collection with custom expression:
.Lambda #Lambda1<System.Func`2[MyProject.Client,System.Object]>(MyProject.Client $var1)
{
.Block() {
.If ($var1.Legal == null) {
.Return #Label1 { (System.Object)($var1.Person).Email }
} .Else {
.Return #Label1 { (System.Object)($var1.Legal).Email }
};
.Label
.Constant<System.Object>(System.Object)
.LabelTarget #Label1:
}
}
However, when attempting cast my collection to list application throws exception:
An exception of type 'System.NotSupportedException' occurred in EntityFramework.SqlServer.dll but was not handled in user code
Additional information: Unknown LINQ expression of type 'Block'.
UPD to Stilgar
I use conditional expression. My sort extension:
public static IOrderedQueryable<TSource> SortMultipleField<TSource>(this IQueryable<TSource> source, string propNames, bool ascending)
{
var type = typeof(TSource);
var param = Expression.Parameter(type);
var sortFields = propNames.Split(',');
Expression firstParent = param;
var firstFieldPath = sortFields[0].Split('.');
foreach (var item in firstFieldPath)
firstParent = Expression.Property(firstParent, item);
firstParent = Expression.Convert(firstParent, typeof(object));
Expression secondParent = param;
foreach (var item in sortFields[1].Split('.'))
secondParent = Expression.Property(secondParent, item);
secondParent = Expression.Convert(secondParent, typeof(object));
var check = Expression.Property(param, firstFieldPath[0]);
var checkNullExpression = Expression.Equal(check, Expression.Constant(null, check.Type));
var returnTarget = Expression.Label(typeof(object));
var block = Expression.Block(
Expression.IfThenElse(
checkNullExpression,
Expression.Return(returnTarget, secondParent),
Expression.Return(returnTarget, firstParent)),
Expression.Label(returnTarget, Expression.Constant(new object())));
var sortExpression = Expression.Lambda<Func<TSource, object>>(block, param);
if (ascending)
return source.OrderBy(sortExpression);
return source.OrderByDescending(sortExpression);
}
I believe Entity Framework does not support statement lambdas only expressions. You may have more luck if you can somehow convert the if statement into a conditional expression.
It seems that you are trying to sort on multiple properties. I think this would be easier to do using the ThenBy method.