C# – The ObjectContext instance has been disposed and can no longer be used for operations that require a connection. – List

cdatabaseentity-frameworknet

In my ASP.NET MVC4 project I got an entity that has a list of another entity.

public virtual IList<SupportTicketMessage> Messages { get; set; }

I can access the messages just fine however when I exit the dbcontext (exit using) I get the error:

The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.

I perfectly understand why I get the error but I'm wondering how I should deal with it? How can I access the messages when I'm not in the dbcontext anymore?

Best Answer

You should include them in your original query. You can do this using Include:

List<Item> items;
using (var context = new YourContext())
{
    items = context.Items.Include(x => x.Messages).ToList();
}

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C# – The ObjectContext instance has been disposed and can no longer be used for operations that require a connection

I suspect the problem is in the code marked ..., which you're not showing.

Make sure to fully evaluate your query before returning it. For example, instead of just doing:

return studentQry;

Try doing:

return studentQry.ToList();

Edit:

Now that you've changed your question to reflect that you're returning IQueryable<T> instead of IEnumerable<T>, there is a separate issue. By returning IQueryable<T> from your method, you're suggesting that the type can be "queried" directly on the server side.

However, WCF is serializing this across the wire, and needs to use a concrete implementation type. IEnumerable<T> is allowed, but not IQueryable<T>. You should switch this to a type that will evaluate fully so the results can be passed correctly.

Best Answer

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C# – The ObjectContext instance has been disposed and can no longer be used for operations that require a connection

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