Call is failing with null parameter

Question

I have the following code: ``` public static ContactEventValue GetContactEventValue(ContactEventType contactEventType, string programCode, string brandCode) { AdvocacyEntities ent = AdvocacyEntities.GetReadOnlyInstance(); ContactEventValue value = ent.ContactEventValues.SingleOrDefault( x => x.ContactEventTypeID == contactEventType.ContactEventTypeID && x.ProgramCode == programCode && x.BrandCode == brandCode); } ``` When I call it with values for brandCode and programCode, I get the expected value back from the database. When I make the call but explicitly setting x.ProgramCode and x.BrandCode to null I get the expected default value back from the database: ``` ContactEventValue value = ent.ContactEventValues.Single( x => x.ContactEventTypeID == contactEventType.ContactEventTypeID && x.ProgramCode == null && x.BrandCode == null); ``` However, when I call the method with null for programCode and brandCode, I get null back from the database! I tried changing the == to .Equals() per the…

Accepted Answer

I don't know what version of EF you're using, but null comparison was an issue prior to version 5. If you inspect the SQL that is actually being emitted, you'll probably see that `IS NULL` is not used in the query.

In EF 6, you'll be able to set the `UseDatabaseNullSemantics` configuration option exposed on `DbContext`:

```
public class MyContext : DbContext
{
    public MyContext()
    {
        this.Configuration.UseDatabaseNullSemantics = true;
    }
}
```

For EF 5, you can use the `UseCSharpNullComparisonBehavior` setting on the underlying `ObjectContext`:

```
public class MyContext : DbContext
{
    public MyContext()
    {
        var objectContextAdapter = this as IObjectContextAdapter;
        objectContextAdapter.
            ObjectContext.ContextOptions.UseCSharpNullComparisonBehavior = true;    
    }
}
```

However, you will need to use .NET Framework 4.5 for your project. If you don't wish to use 4.5, then you can use one of the workarounds listed at How can i query for null values in entity framework?.

Call is failing with null parameter

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