Question

I have a LINQ expression that joins two tables. I want to conditionally check another boolean value: (notice text between ********* below)

bool status = testfunc();

var List = 
    from t in Houses
    join k in Tbl_HouseOwner on t.HouseCode equals k.HouseCode
    where k.ReqCode== t.ReqCode 
    *********** if (status) { where k.Name.Contains(Name) } **********
    select new
    {
        ...
        name = k.Name,
        ...
    };

Answer 1

You can use status to mask the condition, like this:

where k.ReqCode == t.ReqCode && (!status || k.Name.Contains(Name))

If the status is false, the OR || will succeed immediately, and the AND && will be true (assuming that we’ve got to evaluating the OR ||, the left-hand side of the AND && must have been true). If the status is true, on the other hand, the k.Name.Contains(Name) would need to be evaluated in order to finish evaluating the condition.