Re: My Thoughts On My WPF App Design - WPF Discussion Boards

12-Jul-13 11:40

I'd like to get your thoughts on this design...

So I am writing some software for personal use. I'm an independent developer, and I wanted to put together an app to track the work I'm doing and handle invoicing and billing. Conceptually I understand what I want, but programmatically I am working on the design. This is more about me learning than producing an app.

So, I am building this WPF/MVVM app in components. Most pieces are user controls. I decided that I would use relay messages to communicate between the user control a& its host.

For example, the Client View is found in the Client Center.

Each Client is viewed in its own tab in the Client Center. The Client Center has a toolbar with New, Edit, Save, Cancel and Print buttons. Since the center doesn't really know about the Client views in the tabs, the Center will broadcast a message for each function. The Client Center has an instance of a TabManager class, which is a collection of TabItems. The TabItem's Tag property contains the PK of the entity in the tab's content. So, this is available in the View Model.

As an example, when the Save button on the Client Center toolbar is clicked, then it does:

ClientViewSaveMessage message = new ClientViewSaveMessage
{
    // Get the Client's PK from the active tab's Tag property
    Clientid = getActiveTabEntityPK()
};

Messenger.Instance.Send<ClientViewSaveMessage>(message);

Then in the client view I have

//CTOR
public ClientViewModel
{
    messenger.Instance.Register<ClientViewSaveMessage>(p => receiveSaveMessage(ClientViewSaveMessage)p)
}

and then the receiveSaveMessage

private void receiveSaveMessage(ClientViewSaveMessage message)
{
    // Only call Save if the message is for this Client
    if(this.Client.Id == message.ClientId)
    {
        saveChanges();  
    }
}

This technique has the advantage of decoupling all the components. So far it's working well. It's easy to develop, and so far, easy to maintain.

A drawback might be that I will need a lot of messages. I could make one message that has different properties...

Any way, I'd like to hear what you guys think.

Thanks

If it's not broken, fix it until it is

Mycroft Holmes12-Jul-13 13:06

12-Jul-13 13:06

2 things come to mind. You have low expectations of your client base (reasonable in an independant developer) as you are using a tabcontrol as your client collection UI. I would use a grid. In the late 90 after about 5 years of consulting I had well over 50 organisations I was keeping tabs on, once a client or even a quote always a potential.

One reason not to use a messaging paradigm is that it is a bitch to maintain, there is no direct link between the firer of the message and the consumer of that message. a bitch to support.

Never underestimate the power of human stupidity
RAH

Kevin Marois14-Jul-13 13:42

14-Jul-13 13:42

Mycroft Holmes wrote:
You have low expectations of your client base (reasonable in an independant
developer) as you are using a tabcontrol as your client collection UI

I never said that. I said when a client is opened, it's opened in a new tab in the client center. There is a list of clients on the side .

Mycroft Holmes wrote:
One reason not to use a messaging paradigm is that it is a bitch to maintain,
there is no direct link between the firer of the message and the consumer of
that message. a bitch to support.

That's what I said in my OP. Other than that, I cannot see any reason not to use this design,

If it's not broken, fix it until it is

Mycroft Holmes14-Jul-13 14:11

14-Jul-13 14:11

Kevin Marois wrote:
There is a list of clients on the side

Ah somewhat like the outlook bar, that makes sense.

Kevin Marois wrote:
Other than that,

Yeah but support is a major factor in the cost of an app and we will go a long way to make it easier for the next poor sod who has to support the app.

Never underestimate the power of human stupidity
RAH

Kevin Marois15-Jul-13 5:11

15-Jul-13 5:11

SO far it seems to be working well. Overall it's very little code, but the number of message classes is growing. I think that's where the confusion might come in. I could make one generic message class.

As far as knowing who sent a message, the call stack shows that. But I understand what you're saying.

If it's not broken, fix it until it is

Mycroft Holmes16-Jul-14 21:46

16-Jul-14 21:46

Kevin
Can you describe in one paragraph how you constructed your dynamic tab control. I have a similar requirement (max 5 tabs). If so please email me direct (your email is disabled on the messages).

Never underestimate the power of human stupidity
RAH

Kevin Marois17-Jul-14 6:49

17-Jul-14 6:49

I'm not sure what you mean by "constructed your dynamic tab control.

If it's not broken, fix it until it is

Mycroft Holmes17-Jul-14 12:43

17-Jul-14 12:43

I was under the impression your tabcontrol populated the tabs and content based on data rather than at design time. I have a number of ideas how to achieve this but I am trying to reduce the experimentation time required to get it working and was hoping you had already researched this and had some guidance or links to examples you had used.

Never underestimate the power of human stupidity
RAH

Kevin Marois17-Jul-14 12:59

17-Jul-14 12:59

Ok, I see

My tab control is bound to a class, so in the XAML I have

<TabControl Grid.Row="2"
            Grid.Column="2"
            x:Name="MyTabControl"
            BorderBrush="#6593CF"
            Background="White"
            ItemsSource="{Binding TabManager.Tabs}"
            SelectedItem="{Binding TabManager.ActiveTab}"
            Margin="2"/>

My Tab Manager class is this

public class ViewManager : BindableBase, ITabManager
{
    #region Events
    public event EventHandler TabActivated;
    #endregion

    #region Bound Properties
    private ObservableCollection<TabItem> _Tabs = new ObservableCollection<TabItem>();
    public ObservableCollection<TabItem> Tabs
    {
        get { return _Tabs; }
        set
        {
            if (_Tabs != value)
            {
                _Tabs = value;
                RaisePropertyChanged("Tabs");
            }
        }
    }

    private TabItem _ActiveTab;
    public TabItem ActiveTab
    {
        get { return _ActiveTab; }
        set
        {
            if (_ActiveTab != value)
            {
                _ActiveTab = value;
                RaisePropertyChanged("ActiveTab");

                if (TabActivated != null)
                {
                    TabActivated(this, new EventArgs());
                }
            }
        }
    }

    private bool _TabsVisible;
    public bool TabsVisible
    {
        get { return _TabsVisible; }
        set
        {
            if (_TabsVisible != value)
            {
                _TabsVisible = value;
                RaisePropertyChanged("TabsVisible");
            }
        }
    }
    #endregion

    #region Public Methods
    public void ActivateTab(ViewInfo TabInfo)
    {
        var tab = GetTab(TabInfo);
        ActiveTab = tab;
    }
    public void AddTab(TabItem Tab, bool Activate = true, int IndexPosition = -1)
    {
        if (IndexPosition == -1)
        {
            Tabs.Add(Tab);
        }
        else
        {
            Tabs.Insert(IndexPosition, Tab);
        }

        if (Activate)
        {
            ActivateTab((ViewInfo)Tab.Tag);

            // Show/Hide the tab control based on whether there are any tabs open
            TabsVisible = Tabs.Count > 0;
        }
    }
    public bool CloseAllButThisTab(ViewInfo TabInfo)
    {
        bool retVal = true;

        for (int i = Tabs.Count - 1; i >=0; i-- )
        {
            var tab = Tabs[i];
            var tabInfo = (ViewInfo)tab.Tag;

            if (tabInfo.View == TabInfo.View && tabInfo.EntityId == TabInfo.EntityId)
            {
                continue;
            }
            else
            {
                retVal = CloseTab(tabInfo);

                if (!retVal)
                {
                    break;
                }
            }
        }

        return retVal;
    }
    public bool CloseAllTabs()
    {
        bool retVal = true;

        for(int i = Tabs.Count - 1; i > 0; i--)
        {
            var tab = Tabs[i];
            retVal = CloseTab((ViewInfo)tab.Tag);
        }

        return retVal;
    }
    public bool CloseTabAtIndex(int Index)
    {
        Tabs.RemoveAt(Index);
        return true;
    }
    public bool CloseActiveTab()
    {
        return CloseTab((ViewInfo)ActiveTab.Tag);
    }
    public bool CloseTab(ViewInfo TabInfo)
    {
        bool retVal = true;
        var tab = GetTab(TabInfo);

        if (tab != null)
        {
            // Make the tab active
            ActivateTab((ViewInfo)tab.Tag);

            // Get the view off the tab
            var view = (UserControl)tab.Content;

            // If the view is a Center...
            if (view.DataContext is _CenterViewModelBase)
            {
                // Get the view Entity off the center
                _CenterViewModelBase centerVM = (_CenterViewModelBase)view.DataContext;

                // Go through all the tab's subtabs and try to close each one...
                for(int i = centerVM.TabManager.Tabs.Count - 1; i > -1 ; i--)
                //foreach (var centerTab in centerVM.TabManager.Tabs)
                {
                    // Get the tab
                    TabItem centerTab = centerVM.TabManager.Tabs[i];

                    // Call back into this method, passing in the sub tab's View Info to close it
                    bool closed = centerVM.TabManager.CloseTab((ViewInfo)centerTab.Tag);

                    // If the tab was not closed...
                    if (!closed)
                    {
                        // Turn off the retun flag and exit...
                        retVal = false;
                        break;
                    }
                }
            }
            else
            {
                // Get the data entry VM off the tab
                dynamic vm = (_DataEntryViewModelBase)view.DataContext;

                // If the VM has pending changes, prompt the user to save
                retVal = vm.PromptSaveChanges(true);
            }

            // If ok to continue closing...
            if (retVal)
            {
                // If the tab was saved, remove it
                Tabs.Remove(tab);

                // Show/Hide the tab control based on whether there are any tabs open
                TabsVisible = Tabs.Count > 0;
            }
        }

        return retVal;
    }
    public bool HasDirtyTabs()
    {
        bool retVal = false;

        foreach(var tab in Tabs)
        {
            // Activate the tab
            ActivateTab((ViewInfo)tab.Tag);

            // Get the view off the tab
            var view = (UserControl)tab.Content;

            // Get the View Entity off the view
            _DataEntryViewModelBase vm = (_DataEntryViewModelBase)view.DataContext;

            // See if the tab is dirty
            retVal = vm.IsDirty();

            // If so, exit the loop
            if (retVal)
            {
                break;
            }
        }

        return retVal;
    }
    public bool IsTabOpen(ViewInfo TabInfo)
    {
        TabItem tabItem = GetTab(TabInfo);
        return tabItem != null;
    }
    public TabItem GetTab(ViewInfo TabInfo)
    {
        // This doesn't work for some reason
        //TabItem tab = Tabs.Where(t => ((ViewInfo)t.Tag).View == TabInfo.View && ((ViewInfo)t.Tag).EntityId == TabInfo.EntityId).FirstOrDefault();
        TabItem retVal = null;

        foreach (var tab in Tabs)
        {
            ViewInfo vi = (ViewInfo)tab.Tag;

            if (vi.View == TabInfo.View && vi.EntityId == TabInfo.EntityId)
            {
                retVal = tab;
                break;
            }

        }

        return retVal;
    }
    public void RefreshTabInfo(AppMessageArgs Args)
    {
        foreach (var tab in Tabs)
        {
            UserControl view = tab.Content as UserControl;
            _DataEntryViewModelBase vm = view.DataContext as _DataEntryViewModelBase;
            ViewInfo vi = (ViewInfo)tab.Tag;

            if (vi.View == Args.ViewType)
            {
                tab.Header = vm.GetEntityCaption(); ;
                vi.EntityId = vm.GetEntityId();

                tab.Tag = vi;
            }
        }
    }
    public bool SaveAllOpenTabs()
    {
        bool retVal = false;

        foreach (var tab in Tabs)
        {
            // Activate the tab
            ActivateTab((ViewInfo)tab.Tag);

            // Get the view off the tab
            var view = (UserControl)tab.Content;

            // Get the View Entity off the view
            _DataEntryViewModelBase vm = (_DataEntryViewModelBase)view.DataContext;

            // Attempt to save changes
            retVal = vm.PromptSaveChanges(true);

            // If not saved, cancel out
            if (!retVal)
            {
                break;
            }
        }

        return retVal;
    }
    #endregion
}

Then when I want to add a tab from a VM I do this:

private void loadView(BOMArgs Args)
{
    // Create a View Info instance
    ViewInfo tabInfo = new ViewInfo
    {
        View = View.BOM,
        EntityId = Args.BOM.Id
    };

    if (tabInfo.EntityId > 0 && TabManager.IsTabOpen(tabInfo))
    {
        TabManager.ActivateTab(tabInfo);
    }
    else
    {
        // Create an instance of the BOM view Entity and load it
        BOMViewModel vm = new BOMViewModel(Engine);
        vm.Load(Args);

        // Create the view and assign the view Entity to it
        UserControl view = new BOMView();
        view.DataContext = vm;

        // Cretae a tab and assign the presenter view to it
        TabItem tabItem = new TabItem
        {
            Header = vm.GetEntityCaption(),
            Content = view,
            Tag = tabInfo
        };

        // Add the tab and activate it
        TabManager.AddTab(tabItem, true);
    }
}

Works perfect, although I need to de-couple the view => vm dependency in the 'else' section.

If it's not broken, fix it until it is

Mycroft Holmes17-Jul-14 14:09

17-Jul-14 14:09

Excellent, thanks for the info, it clarified my design immensely. Have a bunch of 5s

Never underestimate the power of human stupidity
RAH

WPF ComboBox Problem

Kevin Marois10-Jul-13 19:13

10-Jul-13 19:13

Ok, what am I doing wrong here???

I have a Client Entity:

public class ClientEntity : _EntityBase
{
    private string _ClientName = string.Empty;
    public string ClientName 
    {
        get { return _ClientName; }
        set
        {
            if (_ClientName != value)
            {
                _ClientName = value;
                RaisePropertyChanged("ClientName");
                IsDirty = true;
            }
        }
    }

    private PayTypeEntity _PayType;
    public PayTypeEntity PayType
    {
        get { return _PayType; }
        set
        {
            if (_PayType != value)
            {
                _PayType = value;
                RaisePropertyChanged("PayType");
                IsDirty = true;
            }
        }
    }
}

In my XAML, I am binding the PayTypes combo like this:

<ComboBox Grid.Row="1"
            Grid.Column="3"
            ItemsSource="{Binding PayTypes}"
            SelectedValue="{Binding Client.PayType.Id, Mode=TwoWay}"
            SelectedValuePath="Id"
            DisplayMemberPath="Caption"/>

When I select a PayType it does not get set on the ClientEntity.

If it's not broken, fix it until it is

Re: WPF ComboBox Problem

Richard Deeming11-Jul-13 1:58

Richard Deeming

11-Jul-13 1:58

You're not binding to the PayType property on the ClientEntity class; you're binding to the Id property on the PayTypeEntityClass instance returned from the PayType property on the ClientEntity class.

Try this:

XML

<ComboBox
   Grid.Row="1" Grid.Column="3"
   ItemsSource="{Binding PayTypes}"
   SelectedValue="{Binding Client.PayType}"
   DisplayMemberPath="Caption"
/>

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: WPF ComboBox Problem

Kevin Marois11-Jul-13 17:48

11-Jul-13 17:48

That worked. Thank you

If it's not broken, fix it until it is

Re: WPF ComboBox Problem

Kevin Marois19-Jul-13 16:27

how to make an navigation title dropdownlist

19-Jul-13 16:27

Ok, so I'm still stuck here. I thought this was working, but it's not quite right. It saved the Id ok, but when I reopen it, it doesn't set the value back to what I selected. Here's what I have:

<ComboBox Grid.Row="1" 
            Grid.Column="3"
            IsEnabled="{Binding Path=FieldEnableHelper.PayType}"
            ItemsSource="{Binding PayTypes}"
            SelectedValue="{Binding Client.PayType}"
            DisplayMemberPath="Caption"
            TabIndex="10"
            Style="{StaticResource ComboBoxStyle}"
            Width="150"/>

If it's not broken, fix it until it is

neodeaths10-Jul-13 9:45

neodeaths

10-Jul-13 9:45

hi i am trying to create an navigation bar which allow me to select the page based on the dropdownlist when i select the title
e.g

home->pg1->pg2

and when pg1 is clicked a dropdownbox would dropdown and show the choices which are childs of home.

is there a name or a control which have this already?

please advice

Re: how to make an navigation title dropdownlist

Mycroft Holmes10-Jul-13 12:44

Any Idea CFL in Silverlight?

10-Jul-13 12:44

Never underestimate the power of human stupidity
RAH

Tanmoy Mahish9-Jul-13 19:57

Tanmoy Mahish

9-Jul-13 19:57

I want to make a Choose from list in my silverlight application. like click one button it will show a list of suggestion from that you can choose.

Mycroft Holmes9-Jul-13 21:10

9-Jul-13 21:10

Its called a combo box and it binds to a collection of objects (your class of suggestions) and a selected object, the suggestion the user has selected

Add a button on the view that populates the ObservableCollection<suggestionobject> in the Viewmodel/code behind.

Never underestimate the power of human stupidity
RAH

Tanmoy Mahish9-Jul-13 21:38

Tanmoy Mahish

9-Jul-13 21:38

Sorry but Combo box shows only one dimensional data but I have to show multiple column from that they can choose.

Mycroft Holmes9-Jul-13 22:45

9-Jul-13 22:45

Actually a combobox can take a DataTemplate and display multiple columns.

You use a ListBox or a DataGrid, it really depends on your requirements.

Never underestimate the power of human stupidity
RAH