How can i fix the dispose object error in static methods?

Question

How can i get a list with all the data and reference data from database from a static function? I try to use db.Configuration.LazyLoadingEnabled = true; but the function return only the project info and the reference data was null.

public static Project GetProject(Guid ProjectID)
        {
            if (!ProjectID.Equals(null))
            {
                using (var db = new dbEntity())
                {
                    return db.Projects.Single(Project => Project.Id.Equals(ProjectID));

                }

            }
            return null;
        }

Error:

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

Where i call the function:

@{var project = StaticMethods.GetProject(Guid.Parse(ViewContext.RouteData.Values["id"].ToString()));}
@for(var item in project.Users().ToList()){
 ....
}

@MichaelRandall its a auto-generated model from db ``` public System.Guid Id { get; set; } public string Name { get; set; } public string Number { get; set; } public virtual ICollection Users { get; set; } ``` — Cristian, Apr 08 '19 at 08:50
Also, `if (ProjectID.Equals(null))` is going to throw a NullReferenceException if `ProjectID` is `null`. — CodeCaster, Apr 08 '19 at 08:56

Risto M · Accepted Answer · 2019-04-08T08:54:07.943

You can use Linq eager loading and express explicitly what do you want to include to resulting objectgraph. Eager loading is achieved with .Include()-method.

You did not provide model classes of your entities, but I assume that relationship is one-one (Project has Reference as property). Following snippet loads Project with it's Reference-property:

public static Project GetProject(Guid ProjectID)
{
    if (!ProjectID.Equals(null))
    {
        using (var db = new dbEntity())
        {
            return db.Projects.Include(r => r.Reference).Single(Project => Project.Id.Equals(ProjectID));
        }
    }
    return null;
}

score 0 · Answer 2 · edited Dec 01 '20 at 20:37

0

In short, lazy loading is the problem.

It's caused by the following:

You open the DbContext
Perform your query
Return your Project
Access a virtual property which is trying to lazily load a related resources after the DbContext is disposed.

You will have to do one of the following:

Turn lazy loading off.
Include / Eager load any related resources Project uses.

edited Dec 01 '20 at 20:37

halfer

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answered Apr 08 '19 at 08:48

TheGeneral

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How can i fix the dispose object error in static methods?

2 Answers2