Ticket Q423413

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Override Save, Delete functions

Pawel Botwina

created 13 years ago

Hello,

I'm building an XAF application on legacy database.
I need to create, modify, delete the objects of some types using a API. How to override the functions such a save, delete?

I tried:
protected override void OnSaving()
{
//base.OnSaving();
}

protected override void OnSaved()
{
//base.OnSaved();
}

but Xaf still persists objects as normal - puts record into database.

I want to achieve a functionality like this:

The user cliks save of the detail view.
Instead of xaf saving, I use the API function to save object in the specific manner.

Where to put the code?

Answers approved by DevExpress Support

Dennis Garavsky (DevExpress)

created 12 years ago (modified 12 years ago)

Hello Pawel,
I wrote the following controller to prevent the Detail objects from being saved:

C#
public class Q423413 : ObjectViewController<DetailView, Master> {  
    List<Detail> detailObjectsCache = new List<Detail>();  
    protected override void OnActivated() {  
        base.OnActivated();  
        View.ObjectSpace.CustomCommitChanges += ObjectSpace_CustomCommitChanges;  
        View.ObjectSpace.Committing += ObjectSpace_Committing;  
        View.ObjectSpace.Committed += ObjectSpace_Committed;  
        View.ObjectSpace.Reloaded += ObjectSpace_Reloaded;  
    }  
    protected override void OnDeactivated() {  
        View.ObjectSpace.CustomCommitChanges -= ObjectSpace_CustomCommitChanges;  
        View.ObjectSpace.Committing -= ObjectSpace_Committing;  
        View.ObjectSpace.Committed -= ObjectSpace_Committed;  
        View.ObjectSpace.Reloaded -= ObjectSpace_Reloaded;  
        base.OnDeactivated();  
    }  
    void ObjectSpace_Reloaded(object sender, EventArgs e) {  
        detailObjectsCache.Clear();  
    }  
    void ObjectSpace_Committed(object sender, EventArgs e) {  
        detailObjectsCache.Clear();  
    }  
    void ObjectSpace_Committing(object sender, CancelEventArgs e) {  
        IObjectSpace os = (IObjectSpace)sender;  
        for (int i = os.ModifiedObjects.Count - 1; i >= 0; i--) {  
            object item = os.ModifiedObjects[i];  
            if (typeof(Detail).IsAssignableFrom(item.GetType())) {  
                detailObjectsCache.Add(item as Detail);  
                os.RemoveFromModifiedObjects(item);  
            }  
        }  
    }  
    void ObjectSpace_CustomCommitChanges(object sender, HandledEventArgs e) {  
        //Dennis: Implement a custom saving for your Detail objects here.  
        foreach (Detail detailObject in detailObjectsCache) {  
            //...  
        }  
    }  
}

I also recommend you handle the ObjectSpace.CustomCommitChanges event to plug-in your custom saving algorithm. It will be easier than maintaining your own ObjectSpace. Take special note that you can subscribe to the ObjectSpace events globally in the overridden CreateObjectSpaceCore method of your XafApplication descendant.
I hope you find this information helpful.

Show previous comments (2)

Zoltan Etelvari 12 years ago

Hi Anatol !
"I am afraid that the newly created record cannot be replaced with the existing record."
O.K. I understand that.
I would like only that only update an existing record with the newly created datas, so no insert.
If you view the code above, if it simply disable the INSERT, so no save into database.
Is there any flag to update ?
Thanks, but it will simplify my project. I view your latest answer.
Thanks

Dennis Garavsky (DevExpress) 12 years ago

Hello Zoltan,
If I understand your task correctly, in the simplest case it is sufficient to deactivate the corresponding New Actions via a custom ViewController as shown at How to remove or hide (deactivate, disable) a button ( Action ) from tool bar.
Otherwise, there are no any flags to disable for you. If the UI-level solution I suggested does not meet your needs, then please create a separate ticket and describe your requirements in greater detail.

Zoltan Etelvari 12 years ago

Hi Dennis !
Thanks for the help, I will create the new ticket.
Zoltan

Other Answers

Anatol (DevExpress)

created 13 years ago (modified 9 years ago)

Hello Pawel,
The OnSaving and OnSaved methods are only responsible for throwing the corresponding events. The only way to avoid the object saving via these methods is to throw an exception, but in this case the exception should be handled in your code. However, this is not the recommended way. It appears that the most appropriate solution for your situation is to override the Save action's behavior, as shown in the Override Controller Behavior help topic. Alternatively, implement a custom Object Space (IObjectSpace implementor) and perform the necessary actions in its CommitChanged method. To use the custom Object Space, either override the XafApplication.CreateObjectSpaceCore method, or implement a custom ObjectSpaceProvider and pass it via the XafApplication.CreateCustomObjectSpaceProvider event.

You can learn more on this from the following XAF documentation:
Ways to Implement Business Logic
Create, Read, Update and Delete Data

Show previous comments (8)

Pawel Botwina 13 years ago

Hello,
I've implemented IObjectSpace implementor:
public class XLObjectSpace : XPObjectSpace
    {
        public XLObjectSpace(ITypesInfo typesInfo, XpoTypeInfoSource xpoTypeInfoSource,
            CreateUnitOfWorkHandler createUnitOfWorkDelegate) : base(typesInfo, xpoTypeInfoSource, createUnitOfWorkDelegate)
        {
        }
        protected override void OnCustomCommitChanges(HandledEventArgs args)
        {
            isCommitting = true;
            if (objectsToSave.OfType<CDN_TwrKarty>().Any())
            {
                foreach (var ob in objectsToSave)
                {
                    if (IsNewObject(ob))
                        ApiXL.TowarNowyXL(ob); // saving through API
                    ReloadObject(ob); // not working
                }
                isCommitting = false;
                args.Handled = true;
                DropIsNewCache();
                objectsToSave.Clear();
            }
        }
    }
I have problem with the updating status of Save button and refreshing a ListView.
Can you help me how to tell the XAF that I saved the object?

Dennis Garavsky (DevExpress) 13 years ago

Hello Pawel,
The Save Actions are updated against the IObjectSpace.IsModified property. Our DetailViewController subscribes to the IObjectSpace.ModifiedChanged event and updates its Actions from there.
So, please verify that the SetIsModified(false) method is called in your particular case. If this is OK, then please provide us with your problematic sample project. We will be glad to research it and help you further.

Pawel Botwina 13 years ago

Hello,
I think that SetIsModified(false) is called by CommitChanges() so I don't have to do it.
By the way, the function UpdateActionState() in WinDetailViewController makes two checks:
protected override void UpdateActionState() {
               base.UpdateActionState();
               if((View != null)) {
                    bool changed = ObjectSpace.IsModified || ObjectSpace.IsNewObject(((ObjectView)View).CurrentObject);
…
}
In my project, ObjectSapce.IsNewObject(…) always return true, that's why the Save button is not disabled after save.
Second problem is the new object doesn't appear on the ListView after save.
I've attached the sample project.

Q423413.rar

Dennis Garavsky (DevExpress) 13 years ago

Pawel,
Thank you for your update. About SetModified, I just thought that you might also override the default commit procedure in your code…
You are right about the IsNewObject method, because I see that both problems occur because you do not commit your objects (args.Handled = True):

C#
if(!customCommitArgs.Handled) {  
    DoCommit();  
}

To avoid this problems and to conform to your original business requirements, it will be necessary for you to override the UpdateActionState method and also manually add the objects you created via your routine (you will have to first reread them from the database) to the ListView's CollectionSource.
To learn more on how the latter part is done in XAF by default, check out the ObjectSpace_Committing/ObjectSpace_Committed methods of the DetailViewLinkController class.
I hope you will find this information helpful.

Pawel Botwina 12 years ago

Hello, I have a question in this topic.
I have implemented the custom ObjectSpace and override its DoCommit method. In this method I have custom save and delete functions for nearly every object in my app. I use XPO save method's too (ObjectSpace.CommitChanges()).
I have two objects: Master and Detail. They are associated by non-aggregated collection and represented by DetailView and Nested ListView.
When I modify the Master object - the master's ObjectSpace has 1 object to save.
When I modify the Detail object by double clicking on nested ListView - the detail's ObjectSpace has 1 object to save.
When I modify the Master object and then the Detail object by Inline editing - I have 2 modified objects in the master's ObjectSpace. It's OK.
What I want to do is save the Detail object using the API function and the Master object using the XPO. I can't use Session.CommitChanges() cause it will save the both objects in XPO manner. Session.Save() does not work either.
I have tried to create the new session (UOW), pass the Master object to it and save it only with this new session but with no success.
I need to save only the Master object not all ObjectSpace's objects. Is it possible?
I ran out of ideas.

Dennis Garavsky (DevExpress) 12 years ago

Can't you clone your persistent object into a new Session, modify it and then save it from the session?
You can leverage our built-in Cloner class for that.
If not, or if this does not work for you, I would appreciate a small sample project that can be debugged, so that we can research this situation further.

Pawel Botwina 12 years ago

Change name of the Master object and then change name of the Detail via inline editing (2 modified object in one ObjectSpace).
Save it.
Detail object should be updated via API function (in the sample it's a sample query) and Master should be saved in XPO manner.
In this sample project there are only 2 objects, but in real there are more. The order of saving is unknown.
I've tried Cloner but with no success. It creates new objects and I need only update the existing ones.
All code is in the WinApplication.cs file.

Q423413.rar

Dennis Garavsky (DevExpress) 12 years ago

Pawel, thank you for the clarification. I need some additional time to find the best solution for your requirement. Please bear with me.

Dennis Garavsky (DevExpress) 12 years ago

Hello Pawel,
I wrote the following controller to prevent the Detail objects from being saved:

C#
public class Q423413 : ObjectViewController<DetailView, Master> {  
    List<Detail> detailObjectsCache = new List<Detail>();  
    protected override void OnActivated() {  
        base.OnActivated();  
        View.ObjectSpace.CustomCommitChanges += ObjectSpace_CustomCommitChanges;  
        View.ObjectSpace.Committing += ObjectSpace_Committing;  
        View.ObjectSpace.Committed += ObjectSpace_Committed;  
        View.ObjectSpace.Reloaded += ObjectSpace_Reloaded;  
    }  
    protected override void OnDeactivated() {  
        View.ObjectSpace.CustomCommitChanges -= ObjectSpace_CustomCommitChanges;  
        View.ObjectSpace.Committing -= ObjectSpace_Committing;  
        View.ObjectSpace.Committed -= ObjectSpace_Committed;  
        View.ObjectSpace.Reloaded -= ObjectSpace_Reloaded;  
        base.OnDeactivated();  
    }  
    void ObjectSpace_Reloaded(object sender, EventArgs e) {  
        detailObjectsCache.Clear();  
    }  
    void ObjectSpace_Committed(object sender, EventArgs e) {  
        detailObjectsCache.Clear();  
    }  
    void ObjectSpace_Committing(object sender, CancelEventArgs e) {  
        IObjectSpace os = (IObjectSpace)sender;  
        for (int i = os.ModifiedObjects.Count - 1; i >= 0; i--) {  
            object item = os.ModifiedObjects[i];  
            if (typeof(Detail).IsAssignableFrom(item.GetType())) {  
                detailObjectsCache.Add(item as Detail);  
                os.RemoveFromModifiedObjects(item);  
            }  
        }  
    }  
    void ObjectSpace_CustomCommitChanges(object sender, HandledEventArgs e) {  
        //Dennis: Implement a custom saving for your Detail objects here.  
        foreach (Detail detailObject in detailObjectsCache) {  
            //...  
        }  
    }  
}

Pawel Botwina 12 years ago

Thank you Dennis.
I am using a modified version of your idea and it works.

Dennis Garavsky (DevExpress) 12 years ago

Thank you for your confirmation, Pawel!

Created: August 10, 2012 2:21 PM

Modified: October 6, 2015 7:04 PM

Platform: App Frameworks (UI, API, ORM)

Product: XAF - Specify UI Platform

Build: 12.1.5

IDE: Microsoft Visual Studio 2010

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Override Save, Delete functions

Answers approved by DevExpress Support

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