remove an object from context GetChanges().GetUpdates() list

[AndreaT]

Hi

I have a set of objects that can be loaded or newly added to the context and then (only after been loaded or added) a set of rules determines if those objects have to be persisted.

What is the best way to achieve this? Removing objects from their respective list is correct?

Ctx.GetChanges().GetUpdates<MyObject>().Remove(obj);
//....
Ctx.GetChanges().GetInserts<MyObject>().Remove(obj);
//...

Ctx.SaveChanges();

Thanks

AndreaT

[AndreaT]

I self-reply to my post:

Collection is read-only

well, apparently there is nothing I can do other than a ClearChanges() which clears *all*  the changes not only the desidered.

AndreaT

[IT-Als]

Hi AndreaT,

For the inserts I believe you can remove the object from the context again. Since it have never been persisted., it will just be removed from the scope without issuing a delete, nor an insert statement in SQL.

For the updates, I don't know what to do.

Regards

Henrik

[AndreaT]

Hi Henrik,

i think you are right for the insert. For the updates the doubt still remains. This is my first large scale project with OA (we have dozens of projects my myBatis and nHibernate). At the moment OA lacks of a method to check if an object already exists in the context (I have a DAL that hide insert/update behind a generic save method), right now I intercept the exception eventually thrown by Ctx.Add, second it lacks of a method to get rid of an object from the context without implying a DB delete, that is mimicking the object has never been loaded/added to the context.

AndreaT

[IT-Als]

Hi AndreaT,

Did you check the answer Jan was giving you on this thread?

/Henrik

[Damyan Bogoev]

Hi Andrea,
You could use the approach proposed by Jan and even simplify it. You do not need to obtain the underlying IObjectScope instance for your OpenAccessContext. The OpenAccessContextBase.GetContext method will return the OpenAccessContextBase instance that manages the passed persistent object. You could refactor the IsManagedByMe method in the following way:

 

public bool IsManagedByMe(object o)
{
    OpenAccessContextBase context = OpenAccessContextBase.GetContext(o);
    return ReferenceEquals(context, this);
}

Hope that helps.

Kind regards,
Damyan Bogoev
the Telerik team

[AndreaT]

Hi Damyan,

it sounds good. Your solution comes in handy to build a generic property IsChanged wich refers to the local context.

public bool IsChanged
{
    get
    {

        OpenAccessContextBase ctx = OpenAccessContextBase.GetContext(this);

        return ReferenceEquals(ctx, this) &&
                (ctx.GetChanges().GetUpdates<DbListing>().Contains(this) ||
                    ctx.GetChanges().GetInserts<DbListing>().Contains(this));
    }
}

[Damyan Bogoev]

Hello AndreaT,

Yes, you could use the provided approach to check if the object is in an insert or update mode.
If any other questions arise please contact us back.

Sincerely yours,
Damyan Bogoev
the Telerik team