Question

I have the following 2 methods that i thing could be compressed in one method using generics. What i have tried can not compile. Can someone let me know how this can be done? I need to check that 2 differents field of the table AgeLengths have at least one values.
Str_table has one to many relationship with AgeLengths.

public static bool HasMeanWeight(int id)
{
    MyDataContext dc = new MyDataContext ();
    return  (from s in dc.Str_table 
             where s.SId == id 
             select s.AgeLengths
             .Where(a => a.MeanWeight != null ).Any() == true
            ).FirstOrDefault();
}

public static bool HasNumbersData(int id)
{
    MyDataContext dc = new MyDataContext ();
    return (from s in dc.Str_table 
            where s.sId == id 
            select s.AgeLengths
            .Where(a => a.Numbers  != null).Any() == true
           ).FirstOrDefault();
}

Thanks in advance
B

Answer 1

Update: Apologies, I didn’t realise this was linq to sql. Dennis’s answer appears to be on the mark.

Try injecting a Func<T, TResult> to inject the differing code:

public static bool HasData(int id, Func<AgeLength, object> selector)
{
    MyDataContext dc = new MyDataContext ();
    return (from s in dc.Str_table 
            where s.sId == id 
            select s.AgeLengths
                .Where(a => selector(a) != null)
                .Any())
           .FirstOrDefault();
}

And call like so:

HasData(1, a => a.Numbers);
HasData(1, a => a.MeanWeight);

If the Numbers and MeanWeight properties are in the same inheritance hierarchy, then you can substitute object with something more useful, but in this instance object is fine as you are just testing for null.