Hej,
I'm trying to make som general functionality for my ListView, so that the content of a ListView can be exported to CSV directly.
I'm trying to achive this by getting the datacontext and analysing the ICollectionView for this. From here I have access to the all the objects from via ICollectionView via SourceCollection, in which I (for now) presume sorting/and filtering is respected.
The challange here is that I only want to output the columns that also are showed in the ListView.
When iterating my collection, is there a function where I can evluate if a property in a class (with notification suppoert) has a binding to it?
The esiest solution for now would be just to output all properties, but I'm not interested in this, since oid's are not fun to look at.
Thx in advanced.
/Ian
I suggest you recognize that the ability to determine which data is being displayed is a business requirement. Thus, you should embody this requirement in your model. In other words, your model should clearly indicate which columns are visible - you shouldn't be trying to infer this from your existing properties, nor should you be examining your view.
There are a whole bunch of ways you could do this, but the key is to have this information on hand in your model.
Why don't you just look at the DataTemplate and evaluate it including the binding inside?
There's no easy way to do it... You can check the binding on the target side (dependency property), but not on the source side.
For what you're trying to do, you could loop through the columns of the ListView and check their DisplayMemberBinding, but it could be undefined (the cell content might be defined using the CellTemplate property instead).
Related
I have a list of objects that is being used as the source for a DataGrid. This list of objects is a base class type, of which there are 2 or more inherited types. I am trying to bind to properties of the base class to display as values in the columns of the DataGrid. The subclasses have different properties available to them which I would like to be able to display, so my question is, does XAML have a way to dynamically change the value of a binding based on the type that is being pointed to? I have thought about potentially doing this with a converter, but if I understand correctly, then I would have to write a different converter for each subclass property that I need to bind to. Any advice or suggestions are appreciated. Thanks
This is probably possible, with attributes and some reflection you could mark the properties that should go in the various columns and then auto-generate those. You could also create a sparse grid, with columns for all possible properties; this should also be possible via reflection and does not require any additional metadata.
(You can auto-create the columns based on the items using an attached property (like this) if the native DataGrid event is not sufficient for this.)
You can define multiple DataTemplates and specify the intended type through the DataType property. The correct template will be selected depending on the type of the bound object.
https://msdn.microsoft.com/en-us/library/system.windows.datatemplate.datatype(v=vs.110).aspx
The means to achieve this would be a CellTemplateSelector.
See this link.
I have a listbox that is databound to a List with a bindingsource, what I would like to obtain is that the listbox only shows certain object properties like for example firstName,lastName instead of firstName,lastName,Address,Country,...
How could I manage this?
I'm using winforms.
What about create another type which will be your exact view model and use list of this type?
my last project was a big project in winforms,and i was told that the data bound controls effectively reduce the overall performance of the application.
so the whole group had to work programmatically when adding data to a control,let it be datagrid,combo box,or any other windows control.
i would suggest you do the same too,Adding data to your Controls using code.that way you also decide what you want your clients to see and whatnot.
i would also suggest you take a look here :
how-might-i-add-an-item-to-a-listbox
I apologize for the crappy title, I wasn't quite sure how to summarize what I'm trying to do.
My scenario:
I am refactoring an existing WinForms application to WPF and MVVM. I'm currently working on a module that provides search functionality for a database comprised of many different tables such as Contact, User, Case, Product, etc. In code-behind there are classes which provide an Object for each. I have written wrapper classes for each of the searchable table Objects that expose only the properties a user would want/need to see in the search results for each type of Object, for binding to a DataGrid.
Once these search results exist, they need to be displayed in a combination of Tab Controls and Data Grids, like so:
Because of some use cases, I need to be able to create an individual display Tab+DataGrid for the results of every single search that is performed. I cannot have a single tab for each type of search that is shown/hidden as needed.
I'm not sure how to proceed from where I currently am to the goal pictured and described above. Thanks for any help anyone can provide.
Not sure I entirely understand your question, but it looks to me that it might be a candidate for datatemplateselector.
Basically, you use an ItemsControl bound to your result collection and then - using a datatemplateselector - you swap in the appropriate template to display the item based upon a code inspection.
That will let you present all the results in a single list.
If you want to display your results in a tabs, I would present a collection of each result type in your viewmodel. So you have a Users collection and a seperate Products collection. Then you can bind individual data grids to each template.
If you want to then hide the tabs when no results are present, add a data trigger using the expression.interactivity namespace to trigger the visibility of each tab page based on its respective collection count.
One more thing, if you want to create tab items dynamically, i.e. One tab for each search - the tab control has an ItemSource property. If you group each search result into an object an expose an observable collection of that object, you can bind that to your tab control and have it create tab items for each search result. Just make that object contain a collection of actual results and you should be able to create a itemscontrol as mentioned here already.
Sorry if this appears a bit of a mind dump, but like I said - not sure if I entirely get the question :)
Rather then chuck a load of code snippets in, there a plenty of samples just a google away if anything sounds helpful.
I have a C# CLI program that scans for missing Windows updates and writes them to command line or serializes them to XML depending on the flag passed in. I'm trying to build a WPF component to this but am unsure of a few things. Specifically I'd like to write all missing updates to a grid in the center of my WPF main window. The appearance would be something like this (with gridlines between the fields):
NAME SEVERITY DETECTED
Security Update for Windows 7 (KB1234567) Important 3/9/2014
Security Update for Windows 7 (KB7654321) Critical 3/9/2014
My specific questions:
What type of control would I need to add to the window to house this data?
How do I send the data (detected missing update names and properties) to the grid for display?
How can I set the control so that it is collapsed (or invisible) when no missing updates are detected?
Will I need to add a scrollbar to the grid or will one display automatically?
Apologies for the simple questions. I'm really just looking for some examples to get started, and I haven't been able to find anything thus far that meets my needs.
What type of control would I need to add to the window to house this
data?
DataGrid control is what you are looking for.
How do I send the data (detected missing update names and properties)
to the grid for display?
Bind ItemsSourceof DataGrid to ObservableCollection<T> where T will be class containing data with properties Name, Severity and Detected.
How can I set the control so that it is collapsed (or invisible) when
no missing updates are detected?
Add a DataTrigger to check if ItemsSource collection contains no data, collapse the visibility.
Will I need to add a scrollbar to the grid or will one display
automatically?
DataGrid internally use ScrollViewer. No need to add explicitly.
Refer to the dataGrid samples here and here.
As an alternative DataGrid can offer ListView control, it will be little "easier" than the DataGrid, he also supports the ability to sort columns. For him also need to bind a ItemsSource collection to display:
The ListView control provides the infrastructure to display a set of data items in different layouts or views. For example, a user may want to display data items in a table and also to sort its columns.
Example in MSDN.
Little add some notes to the wonderful answer of #RohitVats, all that has been said about DataGrid also applies to ListView:
How can I set the control so that it is collapsed (or invisible) when no missing updates are detected?
In this situation, I advise you to adhere to the principle of MVVM. Use Binding and Commands to create an independent application. You want to create property (for example IsEnabled) in Model / ViewModel and use bindings to set them in the View, in order to avoid apply directly to the Control. WinForms style app or "regular" applications creates a strong connection between logic and UI, which subsequently impedes further change and application maintenance.
So it seems like what I want to do should be straightforward, but I haven't been able to find a way to do it...
I need to display a list of objects that represent custom elements for entering data. Exactly how each object is displayed depends on the parameters of the object - so it could be a grid containing a name, description, and text box. It could be a grid with a couple labels and a dropdown. It could be an expander that contains multiple sub-objects. It could be something new that hasn't been built yet (so it needs to be extensible). Right now, I am populating this list by creating the FrameworkElement for each object and then adding it to a Grid by hand.
I would like to switch to keeping my objects in an ObservableCollection, and then binding that collection to a ListBox (or similar). That way, when new objects are added or removed from the list, the UI would automatically update itself accordingly. What I can't figure out is, is there a way to point it to my C# method for creating the custom-configured FrameworkElement for each object, so that when new objects are added the appropriate elements will be added to the UI?
Well, you're on the right track as far as wanting to use an ObservableCollection<T> and a ListBox control. Though, I'd venture to say you might want to simply use an ItemsControl since you probably don't care about selecting a particular item, but merely displaying an enumeration of items, and the ListBox would allow you to actually select one of those items.
Your problem is that you want each item in the list to display differently depending on certain criteria. For this you'll want to look at the DataTemplate and DataTemplateSelector classes.
Basically, a DataTemplate is a way of saying "I want my item to look like this.", and a DataTemplateSelector is a way of saying "I want to select this specific DataTemplate based on this criteria."
Here are a few examples on how to use the DataTemplate/DataTemplateSelector classes:
http://tech.pro/tutorial/807/wpf-tutorial-how-to-use-a-datatemplateselector
http://mikestedman.blogspot.com/2009/04/datatemplateselector.html
http://wpftutorial.net/DataTemplates.html
Seperating the presentation from the model is always a good idea. It seems like you are on the right track.
Foreach object type, you should create a DataTemplate and then use ItemTemplateSelector to select the correct template for each object type.
Good luck