CODEWITHSUNDEEP
c#linqentity-framework
Jaan
Jaan

Reputation: 3393

Linq generic parameter error

I know why this is happening but can somebody help me in the right direction of syntax? Currently I have three tables joined by one to one optional relationship. And I joined them as left outer join. My query is....

var model = from t1 in db.Doctors
            join d in db.DoctorAddress on t1.DoctorId equals  d.DoctorId into listi
            join dc in db.DoctorCharges on t1.DoctorId equals dc.DoctorId into listj
            join da in db.DoctorAvailablities on t1.DoctorId equals da.DoctorId into listk
            from d in listi.DefaultIfEmpty()
            from dc in listj.DefaultIfEmpty()
            from da in listk.DefaultIfEmpty()
            select new
            {
                Name = t1.Name,
                RoomNo = da.RoomNo,
                IPDCharge = dc.OPDCharge,
                Address = d.Address,
            };

My problem is that OPDCharge is of type Decimal(not null)

The error I get is:

Exception Details: System.InvalidOperationException: The cast to value type 'Double' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.

What would be the correct syntax?

Upvotes: 1

Views: 135

Answers (3)

stevepkr84
stevepkr84

Reputation: 1657

If you want to accept null as being 0 then try:

IPDCharge = dc.OPDCharge ?? 0;

More info: http://msdn.microsoft.com/en-us/library/ms173224.aspx

Upvotes: 1

Alessandro D'Andria
Alessandro D'Andria

Reputation: 8868

Try with

IPDCharge = dc.OPDCharge.GetValueOrDefault(0)

Upvotes: 0

Magnus
Magnus

Reputation: 46947

I think an explicit cast to a nullable should do it:

IPDCharge = (decimal?)dc.OPDCharge

But the error message suggest that the type of OPDCharge is actually double, so maybe cast to double? instead?

Upvotes: 1

Related Questions