2

I'm having some problems with retrieving my Project entity in the EntityFramework. It keeps giving me the Objest instance has been disposed error.

I've got 2 instances, as seen in the image below.enter image description here

And the following code gives me the error:

    public Project GetProjectyById(int id)
    {
        using (var context = new CoderaDBEntities())
        {
            return context.Projects.First(c => c.Id == id);
        }
    }

Everything from Project is retrieved fine, but the Category object inside the Project object (the association) delivers me the object has been disposed error. What's going on?

Thanks!

Edit: Does this association look odd to you?

Mittchel
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    *"Does this association look odd to you"* - your relationship states 1 category can be associated with many projects, or another way of putting it, each project can only have 1 category. Seems reasonable to me - what should the rule be? – James Nov 04 '12 at 11:23

1 Answers1

5

It looks like you are attempting to access the Category related object using Lazy Loading when the DBContext object has already been disposed (wrapping it in a using statement will dispose it once it goes out of scope). Lazy Loading is when EF loads related entities only when they are requested in the code.

To avoid this you should explicitly load the related object with a Include statement :

return context.Projects.Include("Category").First(c => c.Id == id);

alternatively you could load this in a strongly typed fashion as below but be sure to add the 'using System.Data.Entity; ' reference

return context.Projects.Include(x => x.Category).First(c => c.Id == id);

Another alternative is to allow for Lazy Loading by not wrapping the DbContext object in a using statement as below. 

  public Project GetProjectyById(int id)
    {
        var context = new CoderaDBEntities() 
        return context.Projects.First(c => c.Id == id);       
    }
Judo
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  • Oh god.. I forgot that :o I warned myself to keep that in mind, but stil forgot it :( Thanks Judo! – Mittchel Nov 04 '12 at 11:15
  • By the way.. does the association look right to you? Since I can also make 1 Category instance with multiple project instances (would never happen, but still) – Mittchel Nov 04 '12 at 11:16
  • I'm not quite sure the structure of the data, but if a Project should only have one Category and several Projects could be under the same Category this is correct. If a Project could have multiple Categories then a many-to-many relationship would be best. – Judo Nov 04 '12 at 11:24
  • No, I would like to have 1 category for each Project so its fine like this indeed. I would like to contribute by saying I'm able to turn off Lazy Loading in the EDMX file, but then the Category object is NULL – Mittchel Nov 04 '12 at 11:56