尝试在转换器中转换DesignTime数据时出现InvalidCastException [英] InvalidCastException when trying to cast DesignTime data in a converter

问题描述

我在Expression Blend 4.0中为Silverlight 3.0项目创建了一些设计时数据。我使用"从类创建示例数据..."创建了它。 Blend的Data选项卡中的选项。

示例数据的一个属性是一个自定义类，我们使用IValueConverter将其转换为Polygon上的一组Point。 COnverter中的代码执行此操作

  var   planPoints  = （ 列表<  PlanPoint >）值; 
  var   points  =   new    PointCollection （） ; 
 planPoints.ForEach（pp  =>  points.Add（ new    Point (pp.X, pp.Y))); 
  return   points; 

问题是值参数没有传入我们期望的类型。我们期待List< CompanyName.Data.PlanPoint>但我们得到List< _.di1.CompanyName.Data.PlanPoint>。

为什么混合使用似乎是代理类型的东西以及我们如何阻止它？

TIA

Pat Long

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Pat Long munkiisoft blog

解决方案

您需要将示例数据设置为使用真实类型而不是虚假类型。

 这包括如何在VS中执行此操作。

  http://blogs.msdn.com/b/wpfsldesigner/archive/2010/06/ 30 / sample-data-in-the-wpf-and-silverlight-designer.aspx

干杯，

Karl

I have created some design time data in Expression Blend 4.0 for my Silverlight 3.0 project. I created it using the "Create Sample Data From Class.." option in the Data tab of Blend.

One of the properties on the sample data is a custom class that we convert to a set of Point on a Polygon using an IValueConverter. The code in the COnverter does this

var planPoints = (List<PlanPoint>)value;
var points = new PointCollection();
planPoints.ForEach(pp => points.Add(new Point(pp.X, pp.Y)));
return points;

The trouble is the value argument is not being passed in with the type we would expect. We are expecting List<CompanyName.Data.PlanPoint> but instead we are getting List<_.di1.CompanyName.Data.PlanPoint>.

Why is Blending using what seems to be a proxy type and how can we stop this?

TIA

Pat Long

---

Pat Long munkiisoft blog

解决方案

You need to set the sample data to use Real Types instead of faux types.

 This covers how to do this in VS.

 http://blogs.msdn.com/b/wpfsldesigner/archive/2010/06/30/sample-data-in-the-wpf-and-silverlight-designer.aspx

Cheers,

Karl

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