No way to explain this issue except by example:
Say you have a custom UserControl with two DependencyPropertys, StatList Stats and string ImportantStat. The job of the user control is to display a table showing all of the values in Stats but with special visual treatment (like a pie chart) of the ImportantStat.
My instinct was to write a block of XAML that looked more or less like:
<PieChart Value="{Binding Path={Binding ImportantStat} }"/>
where the DataContext is prior set to Stats. So, the user passes in ImportantStat = "WinPercentage" and the pie chart binds to the WinPercentage Property of the stat line. But the user can just as easily pick some other Property to emphasize.
The problem (of course, you already know this, educated Stacker) is that you get an error message stating that you can't convert from Binding to string, which is what the outer Binding expects for Path. Though I haven't proven it to myself, I am guessing this is simply because Path is not a DependencyProperty.
So, is there any way to achieve my goal here? Feel free to break my assumptions in that first paragraph. Maybe, for example, ImportantStat can't be a string but must itself be a Binding.
Edit: Attempt #1 Failed
I was hoping that exposing from the code-behind a new DependencyProperty Binding ImportantStatBinding would allow me to rewrite the XAML as:
<PieChart Value="{Binding ImportantStatBinding, RelativeSource=... }"/>
...but to no avail. The indirect Binding is just stuck into Value itself with no attempts to resolve it.
My backup solution, which might be where this is headed, will be to just create the content inside the code-behind where I have access to ImportantStat directly and so can get away with a single Binding.
Far as I know, there is no way to concatenate data bindings in this way, without additional code. To put the problem more simply, we can have data binding (of course) of the form:
A --> B --> C
but you cannot have data binding of the form:
A --> B --> *A (*A indicates the target depends on the value of A)
because the relationships must be fixed.
It seems like it might be possible to create a Converter whose job is to convert a string into an arbitrary value by actually dereferencing a Binding using some additional context and that string as the property path. That sounds messy with type issues, so I chose the only other way I could think of:
I added a new DependencyProperty for the PieChart to the code behind and made sure that I constructed it at the appropriate times, so that the XAML could consume it. It's ugly, but it works. I just feel a little dead inside :) Hope someone finds this useful some day.
Related
I have a DevExpress dxe:TextEdit control with EditValueType="{x:Type system:Decimal}". I would like this TextEdit control to display and accept values that are 10,000 times the actual value. E.g., if someone enters 15, it should save the actual value as .0015. And if the value in the viewmodel is .0015, it should display 15.
I am new to WPF and I am not sure the best way to accomplish this. It seems like I can't do it with format strings, but I could be wrong. A value converter seems like overkill. I also thought about modifying the setter on my model object, but I don't think that would work, and it seems sort of hack-y.
I've worked with DevExpress a while ago.
As far as I can remember, you can create your own TextEdit class. (Derive from TextEditBase or even go further and derive from BaseEdit).
However, talking about over-killing, I think this is a much greater over-kill than just creating a converter, which will be a really good solution IMHO.
I would use the get/set functions to accomplish this. Perfect way of using them to translate presentation format to/from storage format.
I want to create a class and its properties on run time, the properties will be like Year2001, Year2002, Year2003, Year2004, Year2005... I get these property names on run-time, I get them in a list. Later I need to use this class to create a list which I need to show in the kendo grid.I surfed a lot and thought of using ExpandoObject, but was unsuccessful.
If all properties will be of the form YearX and contain some information about or related to that year, then I would strongly recommend you (if at all possible) to go with something along the lines of an IList<YearInfo> where YearInfo is some object containing the info you need for every year, including an integer property indicating what year the object corresponds to. If you require these objects to be unique you could use an IDictionary<int, YearObject> or ISet<YearObject> instead.
Reflection can be powerful, but it it comes at the price of complexity and loss of type safety/compile-time checks. Avoid when possible.
Sounds to me like you are really wanting to a grid with grouping support. Your idea of having the system create a CLASS at runtime is not going to fly. Even if it were possible, which I doubt it is, it is absolutely the wrong approach.
Like I say - have a read about Grouping / Hierarchy on Grid Controls (Kendo grid example here), and maybe have a look at OLAP cubes as well...
Although you have had some answers I would also like to suggest an alternative way of doing this which is using DataTables. This is the approach I take when I have any "Dynamic" data sets that I want to present to the grid.
This is also the approach that Telerik themselves take with one of their code samples.
here are a couple of links to show them doing this to DataTables and Dynamic Objects
Grid Binding to Data Table
Grid Binding to Dynamic Objects
Personally I find the binding to Tables easier to deal with as I am used to dealing with Data Tables.
I am trying to get multilingual translation("label or caption") string value for the given elementname in wpf.
For example; for elementname "txtDescription" ; my IValueConverter implementation will return with "Description" ; for another language will return different translation string(i.e. descripción for Spanish) and the translation string will be Text=... of the same element.
I am new to wpf; I cant make it work. Is there any elegant way to do that with similiar manner as below.
<TextBlock Name="txtDescription" Text="{Binding Converter={StaticResource MultiLingualConverter} }"</TextBlock>
If this is not simple or requires more code then as an alternative sending "txtDescription" as an argument to MultiLingualConverter is acceptable but I dont now how to do that neither.
Definitely, you should build good localization support in your system, better then using converter for every string.
Until today, the best solution i have found and i almost always use it is this:
http://blogs.microsoft.co.il/tomershamam/2007/10/30/wpf-localization-on-the-fly-language-selection/
give it a try. good luck
You can pass the element name via the ConverterParameter property, this is an example of how it is used to pass a string to the converter.
However, WPF localization is more than returning different strings for different languages. You can read this article for more information and there is a Run Dialog Box example in the page to get you started.
Due to cyclical dependency restrictions you cannot reference a control inside itself or its descendants in the tree.
I would recommend you not to use converter for multilingual support. it is not a best way to do this.
got here for best way to do.
https://msdn.microsoft.com/en-us/library/ms745650(v=vs.110).aspx
I'm fairly new to WP7 and totally new to Expression Blend.
I have a ListBox bound to a List of custom objects,
List<Person>
Each item in the list contains a custom control, MyControl which is bound to Person.
MyControl contains a TextBox which is bound to the Username property of Person.
All of this works fine. My question is: how do I set a default value for the TextBlock so that it becomes visible in the Designer or ExpressionBlend? With it being data bound, it has no text till it runs ... so I can't actually do any fancy styling using these wonderful tools unless I repeatedly delete the binding code to replace it with a string, make the changes, replace the binding code, repeat. Seems long winded!
Thanks,
Steven
What you want is "Design time data".
There are a number of ways of doing this. Fortunately there are also lots of resources online which explain it.
#Steven Have you looked at creating sample data in Blend to do what you require and then some binding to actually attached the data to the control bound to your list? You might like to check out Blend Sample Data as it guides you through a simple example of doing just that. You might then be able to adapt to to your own ends.
It depends if you are using any MVVM model or not.
My suggestion, if you are not using a MVVM, is to use Blend Sample data, is fast and quick.
If you are MVVM Light I've found very usefull to create two files:
DataService.cs - contains the real connection and data
DesignDataService.cs - contains the sample data
The two libraries are identical, from an call perspective so that in the ViewModelLocator you can swap them:
if (ViewModelBase.IsInDesignModeStatic)
{
SimpleIoc.Default.Register<IDataService, Design.DesignDataService>();
}
else
{
//SimpleIoc.Default.Register<IDataService, Design.DesignDataService>();
SimpleIoc.Default.Register<IDataService, DataService>();
}
In the Design class I've decided to create an XML file for each Model so that it's easy to change the sample data and test all possible scenarios.
I then use the Deserialize function to read it:
csNodeList _Copyrights = new csNodeList();
resource = System.Windows.Application.GetResourceStream(new Uri(#"Design/sampledata.xml", UriKind.Relative));
streamReader = new StreamReader(resource.Stream);
serializer = new XmlSerializer(typeof(csNodeList));
_Copyrights = (csNodeList)serializer.Deserialize(streamReader);
Please note that the file sampledata.xml has to be stored in folder Design and must be defined as Content not as Resource.
It is suggested to improve performance and load time.
M
I thought I had type editors and converters nailed until I tried to persist a Readonly Reference type property after editing it in a UITypeEditor.
In my UITypeEditor, because I'm working with a read only property, I'm careful to pass back the original value (after updating the relevant sub property).
This change is reflected immediately on the designer but will not be persisted unless I do something like resize the control that the property is attached to.
To fix this I, blindly, include a call to context.OnComponentChanged() before returning the value.
I can see why this is needed. It's a reference type, I've altered it (not replaced it), and the property grid doesn't know this. I have a couple of questions for clarification:
Do I need a call to context.OnComponentChanging as well? A simple call to OnComponentChanged works in the tests I've done so far, but I don't want biting on the arse at some point in the future.
Also, is there any danger that, with my call to OnComponentChanging, I'll be persisting other components, in DesignerTransactions, that I shouldn't be persisting?