I am using varbinaries to store extensible bitmasks and am damned if I can figure out how to create an appropriate expression.

I am trying to build up queries from sub expressions like:

(([Applicant].[PreferenceMask] & 1) != 0) AND (([Applicant].[LocationMask] & 8 ) != 0) OR ([Applicant].[PreferenceMask] & 1) = 0)

and

((([Applicant].[PreferenceMask] & 3) != 0) AND ([Applicant].[Bedrooms] > 1) AND [Applicant].[Bedrooms] < 6)) OR ([Applicant].[PreferenceMask] & 1) = 0)

Can I build expressions like this, or am I going to have to implement a sproc

Ryan

You can use SqlServer's bit operators in an expression . It's a bit more work, you first have to create an expression of field bitop value and then use that expression to compare it to a value.

Otis wrote:

You can use SqlServer's bit operators in an expression . It's a bit more work, you first have to create an expression of field bitop value and then use that expression to compare it to a value.

Got that far, but am struggling with the object model a little

RelationPredicateBucket bkt = new RelationPredicateBucket();    
bkt.Relations.Add(ForSaleEntity.Relations.AppraisalEntityUsingForSaleID);

Expression maskBitWiseAnd = new Expression(EntityFieldFactory.Create(ApplicantFieldIndex.PreferenceMask),
    ExOp.BitwiseAnd,LURequirementsListManager.Operations.Fetch("Price").IndexID - 1);

Expression maskBitWiseTrue = new Expression(maskBitWiseAnd,ExOp.NotEqual,0);

Expression maskBitWiseFalse = new Expression(EntityFieldFactory.Create(ApplicantFieldIndex.PreferenceMask),
    ExOp.BitwiseAnd,LURequirementsListManager.Operations.Fetch("Price").IndexID - 1);
    
PredicateExpression maskFalseTest = new Expression(maskBitWiseTrue,ExOp.Equal,0);

PredicateExpression maskTest = new PredicateExpression()
maskTest.AddWithAnd(PredicateFactory.CompareValue(ApplicantFieldIndex.PriceFrom,
    ComparisonOperator.GreaterEqual,((AppraisalEntity)forsale.Appraisal[0]).AskingPrice));
maskTest.AddWithAnd(PredicateFactory.CompareValue(ApplicantFieldIndex.PriceTo,
    ComparisonOperator.LessEqual,((AppraisalEntity)forsale.Appraisal[0]).AskingPrice));     

I figure that is the correct way of building up the expressions and predicates for the query, but am having problems working out how to combine them.

Ryan

The expression: (([Applicant].[PreferenceMask] & 1) != 0) should be formulated as: Field != 0, and you apply the expression Field & 1 to the field. So, you'll do:

EntityField2 field = EntityFieldFactory.Create(ApplicantFieldIndex.PreferenceMask);
field.ExpressionToApply = new Expression(EntityFieldFactory.Create(ApplicantFieldIndex.PreferenceMask), ExOp.BitwiseAnd, 1);
FieldCompareValuePredicate firstFilter = new FieldCompareValuePredicate(field, null, ComparisonOperator.NotEqual, 0);

Then: (([Applicant].[LocationMask] & 8 ) != 0) should be formulated as:

EntityField2 field2 = EntityFieldFactory.Create(ApplicantFieldIndex.LocationMask);
field2.ExpressionToApply = new Expression(EntityFieldFactory.Create(ApplicantFieldIndex.LocationMask), ExOp.BitwiseAnd, 8);
FieldCompareValuePredicate secondFilter = new FieldCompareValuePredicate(field2, null, ComparisonOperator.NotEqual, 0);

Then: ([Applicant].[PreferenceMask] & 1) = 0) should be formulated as: (re-using expression field)

FieldCompareValuePredicate thirdFilter = new FieldCompareValuePredicate(field, null, ComparisonOperator.Equal, 0);

Then, build the predicate expressions. First: (([Applicant].[PreferenceMask] & 1) != 0) AND (([Applicant].[LocationMask] & 8 ) != 0)

PredicateExpression andPredicate = new PredicateExpression(firstFilter, PredicateExpressionOperator.And, secondFilter);

As the Or predicate is already done, we can add it to the complete filter:

PredicateExpression completePredicate = new PredicateExpression(andPredicate, PredicateExpressionOperator.Or, thirdFilter);

so, in full, it looks like:

EntityField2 field = EntityFieldFactory.Create(ApplicantFieldIndex.PreferenceMask);
field.ExpressionToApply = new Expression(EntityFieldFactory.Create(ApplicantFieldIndex.PreferenceMask), ExOp.BitwiseAnd, 1);
FieldCompareValuePredicate firstFilter = new FieldCompareValuePredicate(field, null, ComparisonOperator.NotEqual, 0);

EntityField2 field2 = EntityFieldFactory.Create(ApplicantFieldIndex.LocationMask);
field2.ExpressionToApply = new Expression(EntityFieldFactory.Create(ApplicantFieldIndex.LocationMask), ExOp.BitwiseAnd, 8);
FieldCompareValuePredicate secondFilter = new FieldCompareValuePredicate(field2, null, ComparisonOperator.NotEqual, 0);

FieldCompareValuePredicate thirdFilter = new FieldCompareValuePredicate(field, null, ComparisonOperator.Equal, 0);

PredicateExpression andPredicate = new PredicateExpression(firstFilter, PredicateExpressionOperator.And, secondFilter);
PredicateExpression completePredicate = new PredicateExpression(andPredicate, PredicateExpressionOperator.Or, thirdFilter);

Thanks muchly Frans, normaly wouldn't try to get you to do my work for me, damn deadlines

Ryan