Hi Neil Mercer,
This is by design. When a property is used in a LINQ query, OpenAccess needs to know the field to which this property is associated. This is done via the 'FieldAlias' or 'Storage' attribute. It is not possible to use a property without a correponding field in the database, in a LINQ query.
In order to achieve your aim you could reformulate the query,if possible, in a way that the 'extended property' calculation is pushed to the server, maybe by explicitly specifying it in the query.
Do get back in case you need further assisstance with this.
the Telerik team
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