Is it possible to evaluate a predicate expression without actually sending it to the database? Something like the following code:

PredicateExpression bizzRule = BusinessRulesEngine.Rule1();
bool ruleOK = EvaluateRule(bizzRule, someEntity);

This would be a great way to define business rules only once. We would be able to use the above form in situations where we do complex logic inside C# code and reuse the same expression when fetching a collection that satisfies the business rule.

Sure, you can examine every predicate in the predicate expression. Do a foreach over the PredicateExpression object, and you'll get predicateexpressionelement objects. These can be a predicate, predicate expression or an operator (AND/OR).

I think i'm missing something. The PredicateExpression object is not enumerable.

PredicateExpression test = new PredicateExpression();
foreach(IPredicateExpressionElement element in test)

You're right , use a for loop, use the Count property and use the indexer.

Thanks, i have now a working concept.

The only thing is that it requires a lot of conditional processing. This is probably not the best way under heavy loads. I will try to find some alternatives.

wvnoort wrote:

Thanks, i have now a working concept.

The only thing is that it requires a lot of conditional processing. This is probably not the best way under heavy loads. I will try to find some alternatives.

A predicate contains an enum value, which might help you: InstanceType, it's an int but of type PredicateType. You can use that to quickly determine the actual type of the predicate object: a predicateexpression or a particular predicate class. This can help controlling the flow of the interpretation.