Int[].Contains doesn't work in EF6

Question

I have a strange issue, basically i have this code:

var langauges = (from l in context.languages 
                 where Model.LanguageIDs.Contains(l.LanguageID) 
                 select l)
                .ToList<language>();

I don't know why but I Always get an error:

System.NullReferenceException: Object reference not set to an instance of an object

The thing is it was working before, but after that i've upgraded all my application to MVC5 and EF6, it started to crash on this code.

Although if I check the Model.Langauges, it has several ID's so it is ok.

I also looped through tall the context.Languages and all of them have id's.

I also wrote like this:

var langauges = (from l in context.languages 
                 where 1==l.LanguageID 
                 select l)
                .ToList<language>();

And this WORKS also, so i really don't get it, what am i doing wrong?

Anyone can elaborate ...?

StackTrace:

   at MySql.Data.Entity.SqlGenerator.Visit(DbPropertyExpression expression)
   at MySql.Data.Entity.SqlGenerator.Visit(DbInExpression expression)
   at System.Data.Entity.Core.Common.CommandTrees.DbInExpression.Accept[TResultType](DbExpressionVisitor`1 visitor)
   at MySql.Data.Entity.SqlGenerator.VisitBinaryExpression(DbExpression left, DbExpression right, String op)
   at MySql.Data.Entity.SqlGenerator.Visit(DbAndExpression expression)
   at System.Data.Entity.Core.Common.CommandTrees.DbAndExpression.Accept[TResultType](DbExpressionVisitor`1 visitor)
   at MySql.Data.Entity.SelectGenerator.Visit(DbFilterExpression expression)
   at System.Data.Entity.Core.Common.CommandTrees.DbFilterExpression.Accept[TResultType](DbExpressionVisitor`1 visitor)
   at MySql.Data.Entity.SqlGenerator.VisitInputExpression(DbExpression e, String name, TypeUsage type)
   at MySql.Data.Entity.SelectGenerator.VisitInputExpressionEnsureSelect(DbExpression e, String name, TypeUsage type)
   at MySql.Data.Entity.SelectGenerator.Visit(DbProjectExpression expression)
   at System.Data.Entity.Core.Common.CommandTrees.DbProjectExpression.Accept[TResultType](DbExpressionVisitor`1 visitor)
   at MySql.Data.Entity.SelectGenerator.GenerateSQL(DbCommandTree tree)
   at MySql.Data.MySqlClient.MySqlProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree)
   at System.Data.Entity.Core.Common.DbProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Core.Common.DbProviderServices.CreateCommandDefinition(DbCommandTree commandTree, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition..ctor(DbProviderFactory storeProviderFactory, DbCommandTree commandTree, DbInterceptionContext interceptionContext, IDbDependencyResolver resolver, BridgeDataReaderFactory bridgeDataReaderFactory, ColumnMapFactory columnMapFactory)
   at System.Data.Entity.Core.EntityClient.Internal.EntityProviderServices.CreateCommandDefinition(DbProviderFactory storeProviderFactory, DbCommandTree commandTree, DbInterceptionContext interceptionContext, IDbDependencyResolver resolver)
   at System.Data.Entity.Core.EntityClient.Internal.EntityProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Core.Common.DbProviderServices.CreateCommandDefinition(DbCommandTree commandTree, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlanFactory.CreateCommandDefinition(ObjectContext context, DbQueryCommandTree tree)
   at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlanFactory.Prepare(ObjectContext context, DbQueryCommandTree tree, Type elementType, MergeOption mergeOption, Boolean streaming, Span span, IEnumerable`1 compiledQueryParameters, AliasGenerator aliasGenerator)
   at System.Data.Entity.Core.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable`1 forMergeOption)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClassb.<GetResults>b__a()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClassb.<GetResults>b__9()
   at System.Data.Entity.Infrastructure.DefaultExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.LazyInitValue()
   at System.Lazy`1.get_Value()
   at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at MyProject.Infrastructure.DAL.Operations.UpdateUserinfo(Int32 id, Model Model) in :line 168

yes 1 or 3 or 4 ==l.LanguageID it works, so it only doesn't work with int[].contains :( — Alnedru, Jan 09 '14 at 19:17
You said there are several languages in `Model.Languages`, but in your query you're using `Model.LanguageIDs`. — MarcinJuraszek, Jan 09 '14 at 19:18
I think ,might be simple Contains work else than model.lan.bla bla — Charlie, Jan 09 '14 at 19:19
but the thing is before it was working fine, and normally if i have to int[] i can use contains ... and then why it gives me a null reference exception and not something else :/ What can the other possibliity be to use something else except contains? — Alnedru, Jan 09 '14 at 19:24
You seem to use a MySql provider for EF (according to stack trace). Did you check that it officially supports EF 6? (Or if there is an update for the provider that supports EF 6?) — Slauma, Jan 09 '14 at 19:34
yes, it supports from 6.8.x, and i have 6.8.3 and the thing is i can update everything else except the languages .... and i retrieve the information — Alnedru, Jan 09 '14 at 19:43
Well, the null ref exception is deep inside MySql provider code which, I think, indicates that this is a bug. I'd try to reproduce the problem with a small test model and the same query using `Contains` and if the problem occurs again I'd report this at MySql forum/support. — Slauma, Jan 09 '14 at 20:04
ok, ill try, to do that, meanwhile what would be the workaround for me? No the foreach i hope? ) — Alnedru, Jan 09 '14 at 20:12
I think I'd try `context.Language.SqlQuery(...)...` as workaround for now and build a SQL query string as parameter, probably with an `IN (1,2,3,...)` clause. — Slauma, Jan 09 '14 at 20:20

score 0 · Answer 1 · answered Jan 09 '14 at 19:20

0

Is it possible that Model.LanguageIDs is null or your context has not yet been setup?

Also, do you allow for null language entries in context.languages? If anyone of those is null, you'll get this exception.

answered Jan 09 '14 at 19:20

poy

10,063
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context.languages there is nothing null, all have primary keys etc ... i just did a seperate loop on them and got the ID's. Model.LanguageIDs is also not null i checked it in debug mode – Alnedru Jan 09 '14 at 19:21
1

This is more a comment than an answer, because you are asking clarification questions and taking stabs in the dark. – gunr2171 Jan 09 '14 at 19:21

score 0 · Answer 2 · answered Apr 10 '14 at 09:38

Ok, i am faced exact same problem, but found solution which might help you.

In my case LanguageIDs collection type was List<long>(unisgned int in DB), and LanguageID was int. And this type difference caused problem.

I know, that it's still a bug, and from .net point of view it's absolutely correct, but hope my post will help somebody

Int[].Contains doesn't work in EF6

2 Answers2

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