Question

Possible Duplicate:
How do I combine LINQ expressions into one?

public bool IsUnique(params Expression<Func<Employee, bool>>[] properties)
{
    var combinedProperties = Combine(properties);
    var rowCount = _session.QueryOver<Employee>().Where(combinedProperties).ToRowCountQuery().RowCount();
    return rowCount == 0;
}

Expression<Func<Employee, bool>> Combine(Expression<Func<Employee, bool>>[] properties)
{
    ???
}

Usage:

var isUnique = _employeeRepository.IsUnique(x => x.FirstName == commandMessage.FirstName, x => x.LastName == commandMessage.LastName);

Is there a way of combining predicates with an AND operator?

Answer 1

The simplest way would be to loop over your params array and call .Where for each expression.

Pseudo
var query = _session.QueryOver<Employee>()
for each expression in expressions
   query = query.Where(expression)

I know this isn’t precisely what you asked, but it may be good enough as it achieves the overall goal?