Usually these filter expressions are set from code (in most cases to the client binder controls) and their syntax is the same as an SQL filtering (with AND, OR, DESC and so on). However, there is one thing that I am not sure I understand. Can you give me more details on where exactly do you want to set the filter expression? Do you want to directly set it in the url (with the escaping and everything)? If you have a control, or a field, it would be better to do it inside them, or wire to the client binders and set the filter expression there. I would appreciate a better picture of the end purpose, so that I can give you the right directions on what to use. Thanks in advance.
All the best,
the Telerik team
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