Grid sorting on custom collections

[Martin Dufour]

Hi,

When binding the grid to a List<CutomObject>, it throws an exception (Object Reference Not Set) in System.Linq.EnumerableSorter`2.ComputeKeys.

I already read other threads about that, it seems that setting EnableLinqExpression to false should do the trick.
It doesn't work for me.

I use a LinqDataSource to bind the grid.

Please help, it seems so obvious to me that this should work!

Patrick

[Mira]

Hello Patrick,

I tried to replicate the issue which you described, but to no avail. Attached to this message, you will find the code which I used for testing.

Please, take a look at it and let me know if there are any differences at your end, which I may be leaving out.

Greetings,
Mira
the Telerik team

[Martin Dufour]

Hi,

I forgot to mention an important thing, sorting doesn't work if CutomObject has nested object properties that can be null.
For example, if the column has a SortExpression = "ParentCustomObject.Name" and that ParentCustomObject is null, the exception is thrown.

Anyway, I found a solution for that problem.  For the above example to work, the SortExpression should be:
ParentCustomObject != null ? ParentCustomObject.Name : ""

If fact, the linq framework parse this code so at runtime it works perfect.

Here's the code I use to generate a proper SortExpression:

          

string dataField = GetDataField();

//For each '.' we found, we check null value
string[] split = dataField.Split('.');
if (split.Length == 1)
    return dataField;

//Ex1: "A != null ? A.B : \"\"";
//Ex2: "A != null && A.B != null ? A.B.C : \"\"";
StringBuilder sbObjectToCheck = new StringBuilder();
StringBuilder sbSortExpression = new StringBuilder();
for (int i = 0; i < split.Length - 1; i++)
{
    if (i > 0)
    {
        sbObjectToCheck.Append(".");
        sbSortExpression.Append(" && ");
    }

    sbObjectToCheck.Append(split[i]);
    sbExpression.AppendFormat("{0} != null", sbObjectToCheck.ToString());
}

string sortExpression = string.Format("{0} ? {1} : \"\"", sbExpression.ToString(), dataField);
return sortExpression;

Maybe you should add this workaround in a future release.

Thank you for your quick support !

[Mira]

Hello Patrick,

I am glad that the issue is resolved.

Thank you for sharing the solution with the community.

All the best,
Mira
the Telerik team