How to use the BO business object to achieve a tree-like relationship

[knox007]

I want to create a structure similar to a tree menu. It has many levels. I have created a PageNode class, which is an editable child business object, and PageNode_List, an editable child list .In the PageNode class , there is a child item of type PageNode_List. However, when I attempted to save a PageNode node, an error occurred, indicating that it is not possible to directly save the child items.

[Bowman74]

Sounds like potentially the dataportal.update is being called on a pagenode instance marked as a child. Hard to know without seeing the data portal code for updating the tree.

[StefanOssendorf]

I think the problem here is that you are missing a Root Objectt in your tree.
One list or node needs to be a root which initiates the update and cascades that down to all childs.

[knox007]

Sorry for the late reply. Here are all the bo codes. @Bowman74

[Serializable]
public class PageNode : BusinessBase
{

public static readonly PropertyInfo<string> IdProperty = RegisterProperty<string>(nameof(Id));
public static readonly PropertyInfo<string> NameProperty = RegisterProperty<string>(nameof(Name));
public static readonly PropertyInfo<string> ParentIdProperty = RegisterProperty<string>(nameof(ParentId));
public static readonly PropertyInfo<PageNode_List> ChildrenProperty = RegisterProperty<PageNode_List>(nameof(Children));
#region Exposed Properties and Methods


public string Id
{
    get { return GetProperty(IdProperty); }
    set { SetProperty(IdProperty, value); }
}


public string Name
{
    get { return GetProperty(NameProperty); }
    set { SetProperty(NameProperty, value); }
}


public string ParentId
{
    get { return GetProperty(ParentIdProperty); }
    set { SetProperty(ParentIdProperty, value); }
}

public PageNode_List Children
{
    get { return GetProperty(ChildrenProperty); }
    set { SetProperty(ChildrenProperty, value); }
}


#endregion


#region Validation

protected override void AddBusinessRules()
{
    base.AddBusinessRules();

    // TODO: Add any complex business rules that cannot be achieved through attributes
}

#endregion

#region Authorisation 

[EditorBrowsable(EditorBrowsableState.Never)]
public static void AddObjectAuthorizationRules()
{
    // TODO: Add any per-property authorisation rules required
}

#endregion

#region Data Access

[CreateChild]
private async Task DataPortal_CreateAsync([Inject] IChildDataPortal<PageNode_List> childDataPortal)
{
    using (BypassPropertyChecks)
    {
        // TODO: Set default values for any fields that need to be initialised
        LoadProperty(IdProperty, Guid.NewGuid().ToString()); // Example: Generate a new unique identifier
        LoadProperty(ChildrenProperty,await childDataPortal.CreateChildAsync());

    }
    BusinessRules.CheckRules();

    
}

[FetchChild]
private async Task DataPortal_FetchChildAsync(PageNode_DTO data)
{
    await LoadObjectAsync(data);
}

private Task LoadObjectAsync(PageNode_DTO data)
{
    // Load the object from the DTO
    using (BypassPropertyChecks)
    {
        LoadProperty(IdProperty, data.Id);
        LoadProperty(NameProperty, data.Name);
        LoadProperty(ParentIdProperty, data.ParentId);
        // Complete the load by requesting any children load themselves
    }

    // Check that the object retrieved from the store meets the latest business rules
    BusinessRules.CheckRules();

    return Task.CompletedTask;
}



[InsertChild]
private async Task DataPortal_InsertAsync(PageNode parent,[Inject] IPageNode_Repository repository)
{
    PageNode_DTO data;

    if (repository is null) throw new ArgumentNullException(nameof(repository));

    // TODO: Write parent's unique identifiers into the child
    throw new NotImplementedException("Please write unique identifiers from the parent into this object!");
    data = LoadDTO();
    data.ParentId = parent == null ? string.Empty : parent.Id;
    data = await repository.InsertAsync(data);
    LoadObjectChanges(data);

    // Request that children insert themselves as well
    await FieldManager.UpdateChildrenAsync(this);


}

[UpdateChild]
private async Task DataPortal_UpdateAsync(PageNode parent,[Inject] IPageNode_Repository repository)
{
    PageNode_DTO data;

    if (repository is null) throw new ArgumentNullException(nameof(repository));

  
        if (IsSelfDirty)
        {
            // TODO: Write parent's unique identifiers into the child, if they are editable
            throw new NotImplementedException("Please write unique identifiers from the parent into this object, if they are editable!");
            data = LoadDTO();
            data.ParentId = parent == null ? string.Empty : parent.Id;
            data = await repository.UpdateAsync(data);
            LoadObjectChanges(data);
        }

        // Request that any children update themselves as well
        await FieldManager.UpdateChildrenAsync(this);
 

}

[DeleteSelfChild]
private async Task DataPortal_DeleteSelfAsync([Inject] IPageNode_Repository repository)
{
    if (repository is null) throw new ArgumentNullException(nameof(repository));

    if (IsNew)
    {
        return;
    }
   
    PageNode_DTO data;
    data = LoadDTO();
    await repository.DeleteAsync(data);
    await FieldManager.UpdateChildrenAsync(this);
  
}

private PageNode_DTO LoadDTO()
{
    PageNode_DTO data = new PageNode_DTO();

    data.Id = ReadProperty(IdProperty);
    data.Name = ReadProperty(NameProperty);
    data.ParentId = ReadProperty(ParentIdProperty);

    return data;
}

private void LoadObjectChanges(PageNode_DTO data)
{
    using (BypassPropertyChecks)
    {
        LoadProperty(IdProperty, data.Id);
        LoadProperty(NameProperty, data.Name);
        LoadProperty(ParentIdProperty, data.ParentId);
    }
}



#endregion

}

[Serializable]
public class PageNode_List : BusinessListBase<PageNode_List, PageNode>
{

#region Data Access

[CreateChild]
private Task DataPortal_CreateAsync()
{
    return Task.CompletedTask;
}



[FetchChild]
private async Task DataPortal_FetchChildAsync(IList<PageNode_DTO> items, [Inject] IPageNode_Repository repository, [Inject] IChildDataPortal<PageNode> childDataPortal)
{

    if (repository is null) throw new ArgumentNullException(nameof(repository));

    await LoadObjectsAsync(items, childDataPortal);
}

private async Task LoadObjectsAsync(IList<PageNode_DTO> items, IChildDataPortal<PageNode> childDataPortal)
{
    bool raiseEvents;

    raiseEvents = RaiseListChangedEvents;
    RaiseListChangedEvents = false;

    foreach (var item in items)
    {
        Add(await childDataPortal.FetchChildAsync(item));
    }

    RaiseListChangedEvents = raiseEvents;
}

[UpdateChild]
private async Task DataPortal_UpdateAsync()
{
    using (LoadListMode)
    {
        await Child_UpdateAsync();
    }
}

#endregion

}

[knox007]

It's not a problem of lacking the root object. I added the object, but the problem still occurred. Now I feel that CSLA seems to have limited support for cascading structures. @StefanOssendorf

[StefanOssendorf]

The object graph itself is a cascading structure. That's not the problem.
Is your code above up2date? I can't find a Create or Fetch to create the root object. Furthermore you'd need an Update and/or Insert method in said root object to cascade down to it's children.

[Bowman74]

I've made cascading structures many, many times using CSLA.

[knox007]

Thank you very much for your guidance.I have modified the code according to your instructions, and it is now functioning properly. @StefanOssendorf
`
[Serializable]
public class RootNode : BusinessBase
{

public static readonly PropertyInfo<string> IdProperty = RegisterProperty<string>(nameof(Id));
public static readonly PropertyInfo<string> NameProperty = RegisterProperty<string>(nameof(Name));
public static readonly PropertyInfo<PageNode_List> ChildrenProperty = RegisterProperty<PageNode_List>(nameof(Children));
#region Exposed Properties and Methods

public string Id
{
    get { return GetProperty(IdProperty); }
    set { SetProperty(IdProperty, value); }
}

public string Name
{
    get { return GetProperty(NameProperty); }
    set { SetProperty(NameProperty, value); }
}

public PageNode_List Children
{
    get { return GetProperty(ChildrenProperty); }
    set { SetProperty(ChildrenProperty, value); }
}

#endregion


#region Validation

protected override void AddBusinessRules()
{
    base.AddBusinessRules();

    // TODO: Add any complex business rules that cannot be achieved through attributes
}

#endregion

#region Authorisation 

[EditorBrowsable(EditorBrowsableState.Never)]
public static void AddObjectAuthorizationRules()
{
    // TODO: Define authorisation rules

}

#endregion

#region Data Access



[Create]
[RunLocal]
private async Task DataPortal_CreateAsync([Inject] IChildDataPortal<PageNode_List> childDataPortal)
{
    using (BypassPropertyChecks)
    {
        // TODO: Set default values for any fields that need to be initialised
        LoadProperty(IdProperty, Guid.NewGuid().ToString());
        LoadProperty(ChildrenProperty, await childDataPortal.CreateChildAsync());

    }
    BusinessRules.CheckRules();
    
}



[Insert]
private async Task DataPortal_InsertAsync( )
{
  

    // Request that any children insert themselves as well
    await FieldManager.UpdateChildrenAsync(this);

}

[Update]
private async Task DataPortal_UpdateAsync( )
{        
    //if (IsSelfDirty)
    //{
        
    //}   
    // Request that any children update themselves as well
    await FieldManager.UpdateChildrenAsync(this);


}

[DeleteSelf]
private async Task DataPortal_DeleteAsync( )
{
  
    if (IsNew)
    {
        return;
    }
     
    await FieldManager.UpdateChildrenAsync(this);

}
   
#endregion

}

[Serializable]
public class PageNode_List : BusinessListBase<PageNode_List, PageNode>
{

#region Factory Methods

#endregion

#region Data Access

[CreateChild]
private Task DataPortal_CreateChildAsync()
{
    return Task.CompletedTask;
}
    
[FetchChild]
private async Task DataPortal_FetchChildAsync(IList<PageNode_DTO> items, [Inject] IChildDataPortal<PageNode> childDataPortal)
{  
    await LoadObjectsAsync(items, childDataPortal);
}

private async Task LoadObjectsAsync(IList<PageNode_DTO> items, IChildDataPortal<PageNode> childDataPortal)
{
    bool raiseEvents;

    raiseEvents = RaiseListChangedEvents;
    RaiseListChangedEvents = false;

    foreach (var item in items)
    {
        Add(await childDataPortal.FetchChildAsync(item));
    }

    RaiseListChangedEvents = raiseEvents;
}


#endregion

}

[Serializable]
public class PageNode : BusinessBase
{

public static readonly PropertyInfo<string> IdProperty = RegisterProperty<string>(nameof(Id));
public static readonly PropertyInfo<string> NameProperty = RegisterProperty<string>(nameof(Name));
public static readonly PropertyInfo<string> ParentIdProperty = RegisterProperty<string>(nameof(ParentId));
public static readonly PropertyInfo<PageNode_List> ChildrenProperty = RegisterProperty<PageNode_List>(nameof(Children));

#region Exposed Properties and Methods


public string Id
{
    get { return GetProperty(IdProperty); }
    set { SetProperty(IdProperty, value); }
}


public string Name
{
    get { return GetProperty(NameProperty); }
    set { SetProperty(NameProperty, value); }
}


public string ParentId
{
    get { return GetProperty(ParentIdProperty); }
    set { SetProperty(ParentIdProperty, value); }
}
public PageNode_List Children
{
    get { return GetProperty(ChildrenProperty); }
    set { SetProperty(ChildrenProperty, value); }
}

#endregion

#region Factory Methods

#endregion

#region Validation

protected override void AddBusinessRules()
{
    base.AddBusinessRules();

    // TODO: Add any complex business rules that cannot be achieved through attributes
}

#endregion

#region Authorisation 

[EditorBrowsable(EditorBrowsableState.Never)]
public static void AddObjectAuthorizationRules()
{
    // TODO: Add any per-property authorisation rules required
}

#endregion

#region Data Access

[Create]
private Task DataPortal_CreateAsync()
{
    using (BypassPropertyChecks)
    {
        // TODO: Set default values for any fields that need to be initialised
        LoadProperty(IdProperty, Guid.NewGuid().ToString());

    }
    BusinessRules.CheckRules();

    return Task.CompletedTask;
}


[CreateChild]
private async Task DataPortal_CreateChildAsync([Inject] IChildDataPortal<PageNode_List> childDataPortal)
{
    using (BypassPropertyChecks)
    {
        // TODO: Set default values for any fields that need to be initialised
        LoadProperty(IdProperty, Guid.NewGuid().ToString());
        LoadProperty(ChildrenProperty, await childDataPortal.CreateChildAsync());

    }
    BusinessRules.CheckRules();

    
}


[InsertChild]
private async Task DataPortal_InsertChildAsync(RootNode parent)
{
  
         LoadProperty(ParentIdProperty, parent.Id);
        // Request that children insert themselves as well
        await FieldManager.UpdateChildrenAsync(this);
   

}


[InsertChild]
private async Task DataPortal_InsertChildAsync(PageNode parent)
{

    LoadProperty(ParentIdProperty, parent.Id);
    // Request that children insert themselves as well
    await FieldManager.UpdateChildrenAsync(this);


}
   
[UpdateChild]
private async Task DataPortal_UpdateChildAsync(RootNode parent)
{
    LoadProperty(ParentIdProperty, parent.Id);
    //if (IsSelfDirty)
    //{
            
    //}  
    await FieldManager.UpdateChildrenAsync(this);
      
}


[UpdateChild]
private async Task DataPortal_UpdateChildAsync(PageNode parent)
{
    LoadProperty(ParentIdProperty, parent.Id);
    //if (IsSelfDirty)
    //{

    //}

    await FieldManager.UpdateChildrenAsync(this);

}

[DeleteSelfChild]
private async Task DataPortal_DeleteChildSelfAsync( )
{
    if (IsNew)
    {
        return;
    }   
    await FieldManager.UpdateChildrenAsync(this);
    
}

[DeleteSelf]
private async Task DataPortal_DeleteSelfAsync()
{
    if (IsNew)
    {
        return;
    }
    await FieldManager.UpdateChildrenAsync(this);

}


#endregion

}

`