CODEWITHSUNDEEP
c#linq
Maximus Decimus
Maximus Decimus

Reputation: 5271

How to use OrderBy Linq when object is null and property is integer

I want to order a collection with a property which is null but if not using a property that is integer.

repeaterEmployees.DataSource = employees.Distinct(new EmployeeComparer())
                                        .OrderBy(x => x.Status ?? x.Status.ID);
repeaterEmployees.DataBind();

Employees is a class extending the List`Employee. And Employee has a property Status which is from a class Status

I got a message in the OrderBy method "Operator ?? cannot be applied to operands of type Status and int"

Upvotes: 2

Views: 5129

Answers (2)

Yacoub Massad
Yacoub Massad

Reputation: 27861

You can use -1 (or any other value that you know is outside the range of valid ID values) if Status is null like this:

repeaterEmployees.DataSource =
    employees.Distinct(new EmployeeComparer())
    .OrderBy(x => x.Status == null ? -1 : x.Status.ID );

Upvotes: 9

johnny 5
johnny 5

Reputation: 20995

If this is coming from a SQL DB you should be fine, null references won't happen if calling into the database. If you just call order by, by default nulls will go to the top.

repeaterEmployees.DataSource = employees.Distinct(new EmployeeComparer())
                                    .OrderBy(x => x.Status.ID);
repeaterEmployees.DataBind();

If your calling from linq to objects you'll have to check for null

repeaterEmployees.DataSource = employees.Distinct(new EmployeeComparer())
                                    .OrderBy(x => x.Status == null ? -1 : x.Status.ID);

Upvotes: 0

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