Hi. I need something like this

MyFilter.PredicateExpression.AddWithAnd(false);

With this filter any EntityCollection will be empty.

P.S. Sorry for my english,

Use a filter which will always return false, like PK == -1.

Walaa wrote:

Use a filter which will always return false, like PK == -1.

Thank you, but I want to use filter to fetch ANY kind of entity.

For example, i have OrganizationEntity and CustomerEntity. I need 1 RelationPredicateBucket object for these types.

Drive your own Predicate from any of the available FieldPredicates and override ToQueryText() to produce the sql that your want.

Does this help?

[Serializable]
    public class MatchNonePredicate: Predicate
    {
        public static readonly MatchNonePredicate Instance = new MatchNonePredicate();

        MatchNonePredicate() { }

        protected override bool InterpretPredicate(IEntityCore entity) { return false; }

        public override string ToQueryText(ref int uniqueMarker) { return "(0=1)"; }

        public override string ToQueryText(ref int uniqueMarker, bool inHavingClause) { return "(0=1)"; }
    }

Cheers Simon

Just out of interest - why would you want to run a query to return no entities ?

The usual reason for doing this with a datatable is to get the column names but no data, but if this is the case you can just create a new entity...

Matt

simmotech wrote:

Does this help?

Thank you. This is what I needed.

MTrinder wrote:

Just out of interest - why would you want to run a query to return no entities ?

The usual reason for doing this with a datatable is to get the column names but no data, but if this is the case you can just create a new entity...

Matt

We have a web site with a searh page. The Request parameters are analyzed on this page and if the parameters are incorrect the results of the request will be empty. At searh page there are several UserControls which take RelationPredicateBucket as a property. And my search page returns MatchNonePredicate for these controls in that case.