CODEWITHSUNDEEP
c#asp.net-mvcasp.net-mvc-4entity-framework-5
Sonic Soul
Sonic Soul

Reputation: 24959

Entity Framework 5 database first - null reference in production only

I've been using EF5 db first for some time in a .net 4.5 web project, and it's working well.

I have one query that throws a null reference when calling Count() or ToList() or Any() etc.

        lastQuery =  dbContext.Set<T>();
        logger.Info("last Query: {0}", lastQuery); // this shows the correct query 
        lastQuery.ToList(); // only when the query is executed, null reference is thrown

lastQuery.ToString() shows the correct db query.

this code works from localhost, dev, qa, and localhost pointing to uat/prod database.

entity framework 5 assembly (EntityFramework.dll 5.0.0.net45) is included in deployment and referenced locally.

It only breaks when this code is run on uat/prod server.

it was my suspicion that asp.net mvc 4 was not up to date, so i deployed a standalone install, but that didn't fix it.

looking for ideas on how else to troubleshoot it, or what components may be missing in prod etc..

call stack:

System.NullReferenceException: Object reference not set to an instance of an object.
 at System.Data.EntityKey.ValidateTypeOfKeyValue(MetadataWorkspace workspace, EdmMember keyMember, Object keyValue, Boolean isArgumentException, String argumentName)
 at System.Data.EntityKey.ValidateEntityKey(MetadataWorkspace workspace, EntitySet entitySet, Boolean isArgumentException, String argumentName)
 at System.Data.Objects.ObjectStateManager.CheckKeyMatchesEntity(IEntityWrapper wrappedEntity, EntityKey entityKey, EntitySet entitySetForType, Boolean forAttach)
 at System.Data.Objects.ObjectStateManager.AddEntry(IEntityWrapper wrappedObject, EntityKey passedKey, EntitySet entitySet, String argumentName, Boolean isAdded)
 at System.Data.Common.Internal.Materialization.Shaper.HandleEntityAppendOnly[TEntity](Func`2 constructEntityDelegate, EntityKey entityKey, EntitySet entitySet)
 at lambda_method(Closure , Shaper )
 at System.Data.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper)
 at System.Data.Common.Internal.Materialization.Shaper`1.SimpleEnumerator.MoveNext()
 at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
 at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)

Upvotes: 1

Views: 1272

Answers (2)

Jason
Jason

Reputation: 46

This is a old thread, but I did cannot find the direct answer. Finally, I figure out by checking the code line by line.

In my case: One of the column in view of db is nullable, but the view entity(inside file *.demx) which auto generated by EntityFramework IsNullable was set false by exception. It work good after I modify the IsNullable to true and removed it from key list manually. Alternatively, just delete the view model from the *.edmx and re-update it from the database.

was

// file: *.Designer.cs
[EdmScalarPropertyAttribute(EntityKeyProperty=true, IsNullable=false)]
public global::System.String columnName
{
...
    set
    {
        ...
        _columnName = StructuralObject.SetValidValue(value, false);
        ...
    }
}

// file: *.demx
<Property Name="columnName" Type="varchar" MaxLength="50" Nullable="false" />

is

// file: *.Designer.cs
[EdmScalarPropertyAttribute(EntityKeyProperty=flase, IsNullable=true)]
public global::System.String columnName
{
...
    set
    {
        ...
        _columnName = StructuralObject.SetValidValue(value, true);
        ...
    }
}

// file: *.demx
<Property Name="columnName" Type="varchar" MaxLength="50" Nullable="true" />

Remark

It throw the NullReferenceException exception as value of one of the key column is NULL. Not match the column definition IsNullable=false.

System.NullReferenceException: Object reference not set to an instance of an object. This is the exception message to indicated that a NullReferenceException.

at System.Data.EntityKey.ValidateTypeOfKeyValue... This line indicated that the exception final coming from the key value validation.

Upvotes: 0

Sonic Soul
Sonic Soul

Reputation: 24959

think i figured it out.

since this view is using db first, a primary key has to be defined.

in this case, there was no primary key column, so PK was composite of few fields:

modelBuilder.Entity<V_MVC_USER_ACTION_PERMISSION>().HasKey(u => new { u.LOGIN_NAME, u.CONTROLLER_NAME, u.ACTION_NAME, u.APPLICATION_NAME });

and in production a bunch of records were coming back with null action_name

this appears to be a dbcontext no no, and it will trip with a null context exception.

as a interim solution, i added a filter to my view

where Action_Name is not null

however, it would be nice to find a more comprehensive solution, where all such rows would be ignored instead of nulling the whole return value.

Upvotes: 2

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