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Can you help me with how to use covariance contravariance for the example below?
I am calling a WCF service and want to convert List<srvc.employee> object returned from service to List<employee> object in my wpf app. How to do that?
EmployeeSrv.EmpClient EmployeeSrvc = new EmployeeSrv.EmpClient();
List<EmployeeSrv.Employee> lstEmployee = new List<EmployeeSrv.Employee>();
lstEmployee = EmployeeSrv.GetEmployeeDetails();
List<Employee> lstEmpWPF = lstEmployee;
------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates
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2 thing come to mind, if they are the same why do you care which one you use?
and
List<Employee> lstEmpWPF = new List<Employee>(lstEmployee);
Never underestimate the power of human stupidity
RAH
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I am writing a layered WPF application and want to call a WCF service. The method is below.
I have Presentation - Business - Service and DataAccess layer.
Can you please suggest which layer the below code should be written? Should it be in Business or Service layer?
I am not sure even if there should be two different layers - Business and Service. What do you think?
public List<EmpSrv.Employee> GetUserList()
{
EmpSrv.Client EmployeeSrvc = new EmpSrv.Client;List<EmpSrv.Employee> lstEmployee = new List<EmpSrv.Employee();
try
{
lstEmployee = EmpSrv.GetEmployeeDetails();
}
catch (Exception ex)
{ throw ex;}
return lstEmployee;
}
------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates
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Take a look at MVVM structures, they are very similar to your but if you use MVVM there is a lot of support and examples.
Presentation = View
Business = ViewModel
Service = WCF (has the model)
DAL = DAL (between the WCF and the database)
Never underestimate the power of human stupidity
RAH
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Thanks! I have started looking at MVVM.
------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates
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DotNetXenon wrote: Should it be in Business or Service layer?
It depends on what this code is doing.
It appears that this would go in the business layer.
If it is just populating a list of Employees (without doing any business layer stuff) then it could even be in the presentation layer.
Too much of heaven can bring you underground
Heaven can always turn around
Too much of heaven, our life is all hell bound
Heaven, the kill that makes no sound
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WCF Service returns List<employee>. I call from wpf app and have User class which contains the same properties as Employee class in wcf service.
Eservice EmployeeSrvc = new Eservice();
List<user> lstUser= new List<user>();
lstEmployee = EmployeeSrvc.GetEmployeeDetails();
I get the error "Cannot implicitly convert type .."
I am not sure how to convert the WCF return list to List<user> in my wpf app. Please help!
------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates
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Hi,
"List" is a generic type which means, it provides functionality, which can be applied to abitrary (other) types. That's why you can't have "List" as the return type of a webservice (or just any method), but List<T> where "T" is another type.
If you have two instances of List<T> and the involded "T"s are different, the List-types are not convertible (neither implicitly nor explicitly). So, if you have
List<User> lstUser = new List<User>(); you can't assign the result of
List<Employee> lstEmployee = EmployeeSrvc.GetEmployeeDetails(); This is true for .Net until 3.5; in .Net 4 MS has made some improvements. Just search for "covariance"/"contravariance".
If "Emplpoyee" and "User" have the same properties, you should just use one class (e. g. "Person").
Another possible solution could be to loop through the results of the service (employees) and create and add new users.
Cheers
Jürgen
If this answer saves you some time, please spend a bit of it to vote.
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Jurgen, Thanks a ton!
I used the same List<employee> which is used in the WCF service instead of creating List<user> in my application separately like below.
Eservice EmployeeSrvc = new Eservice();
List<eservice.employee> lstEmployee = new List<eservice.employee>();
lstEmployee = EmployeeSrvc.GetEmployeeDetails();
------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates
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i have one multi series line chart. i m displaying datetime on x-axis. i have rotate my datetime values by 270 degree angle. now problem is that x-axis values showing on two places on chart. one at bottom and aother at top of chart area. i need only one x-axis valur as we do in any standard chart.
my code is:
<UserControl xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
xmlns:toolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit" x:Class="TestExcelChart.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:charting="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit"
xmlns:layout="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Layout.Toolkit"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<UserControl.Resources>
</UserControl.Resources>
<Canvas x:Name="LayoutRoot" Background="White" Width="600" >
<sdk:TabControl x:Name="pnlxlChart" TabStripPlacement="Top" VerticalAlignment="Top"
Height="700" Width="600" HorizontalAlignment="Left" Canvas.Left="24"
>
<sdk:TabItem Height="20" Header=" Excel Data">
<StackPanel>
<sdk:DataGrid x:Name="excelData" AutoGenerateColumns="False" />
</StackPanel>
</sdk:TabItem>
<sdk:TabItem Height="20" Header="Column Chart">
</sdk:TabItem>
<sdk:TabItem Height="20" Header="Line Chart">
<charting:Chart x:Name="LineChart" Grid.Row="2" Title="Line Chart" Height="500">
<charting:Chart.Series>
<charting:LineSeries DataContext="users"
IndependentValuePath="Name" DependentValuePath="Score" >
<charting:LineSeries.IndependentAxis>
<charting:CategoryAxis Orientation="X">
<charting:CategoryAxis.AxisLabelStyle>
<Style TargetType="charting:AxisLabel">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="charting:AxisLabel">
<layout:LayoutTransformer>
<layout:LayoutTransformer.LayoutTransform>
<RotateTransform Angle="270"/>
</layout:LayoutTransformer.LayoutTransform>
<TextBlock Text="{TemplateBinding FormattedContent}" RenderTransformOrigin="0.5,0.5"/>
</layout:LayoutTransformer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</charting:CategoryAxis.AxisLabelStyle>
</charting:CategoryAxis>
</charting:LineSeries.IndependentAxis>
</charting:LineSeries>
<charting:LineSeries DataContext="users"
IndependentValuePath="Name" DependentValuePath="Score2" >
<charting:LineSeries.IndependentAxis>
<charting:CategoryAxis Orientation="X">
<charting:CategoryAxis.AxisLabelStyle>
<Style TargetType="charting:AxisLabel">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="charting:AxisLabel">
<layout:LayoutTransformer>
<layout:LayoutTransformer.LayoutTransform>
<RotateTransform Angle="270"/>
</layout:LayoutTransformer.LayoutTransform>
<TextBlock Text="{TemplateBinding FormattedContent}" RenderTransformOrigin="0.5,0.5" />
</layout:LayoutTransformer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</charting:CategoryAxis.AxisLabelStyle>
</charting:CategoryAxis>
</charting:LineSeries.IndependentAxis>
</charting:LineSeries>
</charting:Chart.Series>
</charting:Chart>
</sdk:TabItem>
</sdk:TabControl>
</Canvas>
</UserControl>
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Hi,
How to open or navigate to a XAML page from a button click in the .aspx page in the .web project.
Thankyou
YPKI
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Redirect .aspx to the page that's hosting the Xaml!
C# has already designed away most of the tedium of C++.
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Hi all -
I added a Silverlight application to my solution - an asp.net website.
It added an html and aspx file in the root, also a ClientBin dir.
If I link to the html or aspx file, the SL content displays - in a page by itself.
So, I tried to add the SL object to an asp:wizard page. I copied the div from the aspx and put it on the page. I also added the javascript error code and the link to the js file.
The SL content wont show in the wizard. I set the source to "..\\ClientBin\..." and the js to "..\\silverlight.js" because the wizard is at the same level as the ClientBin content. changing the size and background of the object does work, and not adding ..\\ causes the javascript onerror code to execute.
Can anyone let me know what else I need to do? Any help would be appreciated.
Thanks!
J
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Have you tried to change the width and height to pixels instead of %?
This post may be of help : http://forums.silverlight.net/p/232055/569580.aspx[^]
------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates
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Hi Xenon - thanks for the response.
Yes I tried setting the height and width to pixels and I do get a box that will bring up the silverlight menu when you right click inside it, but thats all.
Basically, if the pages that load the sl object are in the root of my project - like the test aspx and html pages added by default when the sl project is created - it works fine.
If I try and load the sl object from a page in a folder (at the same level as ClientBin) It doesn't work. even if I copy the same html or aspx pages directly from the root.
I have to change a couple things -
<param name="source" value="ClientBin/Silverlight Object.xap"/>
becomes
<param name="source" value="..\\ClientBin/Silverlight Object.xap"/> and
<script type="text/javascript" src="Silverlight.js"></script>
becomes
<script type="text/javascript" src="..\\Silverlight.js"></script>
(I don't think the .js is being used, so I don't think I need to do this. If I don't change the ClientBin to ..\\ClientBin, I will get a load error thrown.
Do I need to set mime types or something? I read something about them only being set for the root of the project directory. I am using VS2010.
Thanks!
J
here's the page source I get -
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>
Silverlight Object
</title>
<style type="text/css">
.style1
{
width: 100%;
}
html, body {
height: 100%;
overflow: auto;
}
body {
padding: 0;
margin: 0;
}
#silverlightControlHost {
height: 500px;
text-align:center;
}
</style>
<script type="text/javascript" src="..\\Silverlight.js"></script>
<script type="text/javascript">
function onSilverlightError(sender, args) {
var appSource = "";
if (sender != null && sender != 0) {
appSource = sender.getHost().Source;
}
var errorType = args.ErrorType;
var iErrorCode = args.ErrorCode;
if (errorType == "ImageError" || errorType == "MediaError") {
return;
}
var errMsg = "Unhandled Error in Silverlight Application " + appSource + "\n";
errMsg += "Code: " + iErrorCode + " \n";
errMsg += "Category: " + errorType + " \n";
errMsg += "Message: " + args.ErrorMessage + " \n";
if (errorType == "ParserError") {
errMsg += "File: " + args.xamlFile + " \n";
errMsg += "Line: " + args.lineNumber + " \n";
errMsg += "Position: " + args.charPosition + " \n";
}
else if (errorType == "RuntimeError") {
if (args.lineNumber != 0) {
errMsg += "Line: " + args.lineNumber + " \n";
errMsg += "Position: " + args.charPosition + " \n";
}
errMsg += "MethodName: " + args.methodName + " \n";
}
alert(errMsg);
throw new Error(errMsg);
}
</script>
</head>
<body>
<form method="post" action="Page1.aspx" id="form1">
<div class="aspNetHidden">
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUJODExMDE5NzY5ZGR3pKj0yol3dSXA8CS0ZrlCCYJQXLMakDaYymKobcWj8w==" />
</div>
<span id="Label1">Not Silverlight</span>
<div id="silverlightControlHost">
<object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="400px" height="400px">
<param name="source" value="..\\ClientBin/Silverlight Object.xap"/>
<param name="onError" value="onSilverlightError" />
<param name="background" value="blue" />
<param name="minRuntimeVersion" value="4.0.50826.0" />
<param name="autoUpgrade" value="true" />
<a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50826.0" style="text-decoration:none">
<img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/>
</a>
</object><iframe id="_sl_historyFrame" style="visibility:hidden;height:0px;width:0px;border:0px"></iframe></div>
</form>
</body>
</html>
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- my own stupid mistake.
<param name="source" value="..\\ClientBin/Silverlight Object.xap"/>
should have been -
<param name="source" value="../ClientBin/Silverlight Object.xap"/>
it is working great now 
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Hey,
Ive wrote a WPF application and now i wont to give a user the this feature:
1.User will write some DLL that will be based on WPF GUI.
2.When the user will ask my application to load his DLL my APP will load it and present it on the main window then user will work with it.
3.After he will finish to work with it he will ask to unload it.
Question:
1.How it possible to write DLL with WPF GUI?
2.I dont know which DLL's will be so i need to load them dynamicly,how can i do this(maybe user have to implement some inteface in his DLL)?
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To be able to unload dll's you need to load them into a separate ApplicationDomain and when you are done with the dll you need to unload the AppDomain.
//daniel
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I've added xmlns="" to all my XmlDataProvider (after Googling for sometime[^]), but from Visual Studio output Window still getting the very annoying error message - "XmlDataProvider has inline XML that does not explicitly set its XmlNamespace (xmlns="")"
<XmlDataProvider x:Key="MoreColors" XPath="/colors">
<x:XData>
<colors xmlns="" >
<color name="pink"/>
<color name="white"/>
<color name="black"/>
<color name="cyan"/>
<color name="gray"/>
<color name="magenta"/>
</colors>
</x:XData>
</XmlDataProvider>
Any idea? Thanks
dev
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I reproduced your code but it works fine here without any issues. Have you inserted this code inside a resources tag? Eg:
<Grid.Resources>
<XmlDataProvider x:Key="MoreColors" XPath="/colors">
<x:XData>
<colors xmlns="" >
<color name="pink"/>
<color name="white"/>
<color name="black"/>
<color name="cyan"/>
<color name="gray"/>
<color name="magenta"/>
</colors>
</x:XData>
</XmlDataProvider>
</Grid.Resources>
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I almost never use ToString(), but when I do, its for a representation of the entire object. The DataTemplate is binding to a single property (or multiple ones with a value converter).
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DataTemplate is actually often used for the represantation of the entire object, arbitrarily complex (both the object and the representation).
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If I only need to show 1 value in my combobox I normally just set the DisplayMemberPath of the combobox to the property I want to show.
It is said that your life flashes before your eyes just before you die. That is true, it's called Life. - Terry Pratchett
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I would say that ToString "converts" the whole object to a string, simple as that. Which means 1) you can't return any fancy colorful represantation other than a simple string and 2) the ToString() is global application-wise, meaning that you can't make two comboboxes displaying the same list of items make display slightly different things (which you can do with DataTamplates).
DataTemplates are much more versatile, can be specific for a particular control (combobox) or used globally. They can also display much more complex data than just a string.
Then there are value converters...
The call is yours, ToString may be just fine for simple combobox item represatation, setting ItemTemplate doesn't hurt either.
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I wasn't wrong, just not really answering your question, sorry for that. I just wanted to outline the main differences between the two approaches, which is not really what you asked. Ad 1) sure, VM does not return colors, what I had in mind was a rather more complex object than just DisplayName and then ToString() forces you to condense all the data to one string, which can be very limiting and styling is of no help. Ad 2) of course you can use DataTemplates but I was talking about limitations of ToString().
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