FileDescriptor.Value : Handling null value

[Steven]

Good morning,

I am using your CustomFilterDescript sample from your RadControl demos and I have an error when my descriptor.value is null.

private IFilterDescriptor CreateFilterForColumn(GridViewDataColumn column)
        {
            FilterOperator filterOperator = GetFilterOperatorForType(column.DataType);
            FilterDescriptor descriptor = new FilterDescriptor(column.UniqueName, filterOperator, this.filterValue);
            descriptor.MemberType = column.DataType;

            return descriptor;
        }

For example I have : ColumnName is EqualTo Null.
This produce an error on this line :

convertedValue = Convert.ChangeType(this.FilterValue, descriptor.MemberType, CultureInfo.CurrentCulture);

How can I handle this?

Regards,
Steven

[Rossen Hristov]

Hello Steven,

Add a check for when a null value arrives and replace it with the special singleton value FilterDescriptor.UnsetValue. When the Value if a FilterDescriptor is FilterDescriptor.UnsetValue it is as though it does not exist at all.

Alternatively, you can modify the code to do nothing, i.e. to not produce any descriptor when the incoming value is null.

I hope this helps.

Greetings,
Ross
the Telerik team

[Steven]

Thank you :)