CODEWITHSUNDEEP
c#entity-frameworklambda
prashant
prashant

Reputation: 471

Error in selecting nullable using linq to Entities

I am using linq to Entities. I am trying to select a nullable Int field with below code but I am getting Exception

    List<MyClass> myList = myContext.Accounts
            .Where(x => x.ACCOUNT_TYPE_ID == 58 && x.IS_DELETED == 0)
            .Select(x=> new PayorCode
                {
                    Id = x.ID,
                    Payor = x.CODE_NUM + " - "+ x.DESCRIPTION
                }).ToList();


In Accounts property CODE_NUM is of Nullable<global::System.Int32> .

I am getting the below exception

Unable to cast the type 'System.Nullable`1' to type 'System.Object'. LINQ to Entities only supports casting EDM primitive or enumeration types.

How should I use the nullable field in Linq to Entites ? I tried with Convert.ToInt32 and object.Equals but both didn't worked.
Any help will be appreciated

Upvotes: 1

Views: 1621

Answers (2)

Patrick Hogan
Patrick Hogan

Reputation: 1

The class list "List" can't be used with the strongly type class list PayorCode referenced in your select. Either use a "var query = ..." along with PayorCode or if List is the same as PayorCode then substitute PayorCode with MyClass. So .Select(x => new MyClass { ....}

Then answer 2 should work fine.

Upvotes: -1

Jamiec
Jamiec

Reputation: 136154

Dealing with nullable ints in EF should be no different to dealing with them under normal circumstances. You can check that they have a value using .HasValue, you can read the value directly using .Value and you can null-coalesce using ??. Depending on what you want to happen in the case that this property is null, you should be able to do something along the lines of:

.Select(x=> new PayorCode
            {
                Id = x.ID,
                Payor = x.CODE_NUM.HasValue 
                            ? x.CODE_NUM.Value + " - "+ x.DESCRIPTION
                            : "CODE_NUM Missing"
            })

or perhaps:

.Select(x=> new PayorCode
            {
                Id = x.ID,
                Payor = (x.CODE_NUM ?? "0") + " - "+ x.DESCRIPTION,
            })

Upvotes: 3

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