我正在使用Entity Framework在WPF应用程序上使用VS 2015。 在这个应用程序中，我在我的一个WPF窗口中可以序列化一个画布，我在其上获得了一些自定义控件。
今天我尝试向我的一个自定义控件添加一个新的dependencyproperty，它是一个observablecollection，类型是一个实体（在我的例子中是一个名为Formulas的表）。
通常，不可能序列化泛型类型。
所以我在我的应用程序中添加了一个新类，并在我的代码中将其用作属性类型。
public class AssignedFormulasCollection : ObservableCollection<Formulas> { public AssignedFormulasCollection() { } public AssignedFormulasCollection(List<Formulas> list) : base(list) { } }这是实体Formulas的代码：
public partial class Formulas { public Formulas() { this.Formula_Attributes = new HashSet<Formula_Attributes>(); this.Formula_Field_Attributes = new HashSet<Formula_Field_Attributes>(); this.Input_Field_Formulas = new HashSet<Input_Field_Formulas>(); this.Stepfunctions = new HashSet<Stepfunctions>(); } public int formula_id { get; set; } public int description_id { get; set; } public string formula_name { get; set; } public string formula_version { get; set; } public string formula_expression { get; set; } public string formula_type { get; set; } public Nullable<float> result1 { get; set; } public Nullable<float> result2 { get; set; } public Nullable<float> result3 { get; set; } public Nullable<int> version { get; set; } public string changer { get; set; } public Nullable<System.DateTime> change_date { get; set; } public virtual Descriptions Descriptions { get; set; } public virtual ICollection<Formula_Attributes> Formula_Attributes { get; set; } public virtual ICollection<Formula_Field_Attributes> Formula_Field_Attributes { get; set; } public virtual ICollection<Input_Field_Formulas> Input_Field_Formulas { get; set; } public virtual ICollection<Stepfunctions> Stepfunctions { get; set; } }我通过这种方法序列化画布：
public string SerializeControlToXaml(FrameworkElement element) { var elementToXaml = new StringBuilder(); var settings = new XmlWriterSettings(); settings.Indent = true; settings.OmitXmlDeclaration = true; var serializationManager = new XamlDesignerSerializationManager(XmlWriter.Create(elementToXaml, settings)); serializationManager.XamlWriterMode = XamlWriterMode.Expression; XamlWriter.Save(element, serializationManager); var xaml = elementToXaml.ToString(); return xaml; }但是当我尝试使用自定义控件序列化画布时，我收到以下错误消息：
用户代码未处理System.Reflection.TargetInvocationException。 HResult = -2146232828 Message = System.Data.Entity.DynamicProxies.Formulas_CF5776A4E794BA378BEBDBE1E29E7967B4AACCF844AB5416006C852677145A0A对象的PropertyAccessorDescriptions导致以下异常：ObjectContext实例已被丢弃，无法再用于需要连接的事务。
来源=系统
堆栈跟踪： 在System.ComponentModel.ReflectPropertyDescriptor.GetValue（对象组件） 在System.Windows.Markup.Primitives.ElementProperty.get_Value（） 在System.Windows.Markup.Primitives.ElementPropertyBase.get_IsComposite（） 在System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces（ScopeScope，MarkupObject项，IValueSerializerContext上下文，布尔lastWasString） 在System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces（ScopeScope，MarkupObject项，IValueSerializerContext上下文，布尔lastWasString）在System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces（ScopeScope，MarkupObject项，IValueSerializerContext上下文，布尔lastWasString）在系统.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces（ScopeScope，MarkupObject项，IValueSerializerContext上下文，Boolean lastWasString）在System.Windows.Markup.Primitives.MarkupWriter.WriteItem（MarkupObject项）At System.Windows.Markup.Primitives.MarkupWriter.SaveAsXml （XmlWriter writer，MarkupObject项）在System.Windows.Markup.Primitives.MarkupWriter.SaveAsXml（XmlWriter writer，Object instance，XamlDesignerSerializationManager manager）At System.Windows.Markup.XamlWriter.Save（Object obj，XamlDesignerSerializationManager manager）At P16Common.XamlDeSerializer .SerializeControlToXaml（FrameworkElement元素） 在C：\ svn_checkout \ P16_RoeV \ Sourcen \ P16Admintool_develop \ P16Common \ XamlDeSerializer.cs：第50行。在P16Common.CommonMethods.SerializeToXml（FrameworkElement designerGrid）到C：\ svn_checkout \ P16_RoeV \ Sourcen \ P16Admintool_develop \ P16Common \ CommonMethods.cs：Line 61.在P16Admintool.Helper.InputMaskHelper.UpdateInputMask（InputMasksView designerwindow）到C：\ svn_checkout \ P16_RoeV \ Resources \ P16Admintool_develop \ P16Admintool \ Helper \ InputMaskHelper.cs：第39行。在C16中的P16Admintool.ViewModels.ChangeElementPropertiesViewModel.SetElementProperties（）： \ svn_checkout \ P16_RoeV \ Sourcen \ P16Admintool_develop \ P16Admintool \ ViewModels \ ChangeElementPropertiesViewModel.cs：第152行。对于C：\ svn_checkout \ P16_RoeV \ Resources \ P16Admintool_develop \ P16Admintool \ Views中的P16Admintool.Views.ChangeElementProperties.btn_set_properties_Click（Object sender，RoutedEventArgs e） \ ChangeElementProperties.xaml.cs：第77行。 在System.Windows.RoutedEventHandlerInfo.InvokeHandler（Object target，RoutedEventArgs routedEventArgs）在System.Windows.EventRoute.InvokeHandlersImpl（Object source，RoutedEventArgsArgs，Boolean reRaised）At System.Windows.UIElement.RaiseEventImpl（DependencyObject sender，RoutedEventArgs args）At System。 Windows.UIElement.RaiseEvent（RoutedEventArgs e）在System.Windows.Controls.Primitives.ButtonBase.OnClick（）At System.Windows.Controls.Button.OnClick（）At System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp（MouseButtonEventArgs e ）在System.Windows.UIElement.OnMouseLeftButtonUpThunk（Object sender，MouseButtonEventArgs e）System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler（Delegate genericHandler，Object genericTarget）At System.Windows.RoutedEventArgs.InvokeHandler（Delegate handler，Object target）At System .Windows.RoutedEventHandlerInfo.InvokeHandler（Object target，RoutedEventArgs routedEventArgs）在System.Windows.EventRoute.InvokeHandlersImpl（Object source，RoutedEventArgsArgs，Boolean reRaised）At System.Windows.UIElement.ReRaiseEventAs（DependencyObject sender，RoutedEventArgs args，RoutedEvent newEvent）At System.Windows.UIElement.OnMouseUpThunk（Object sender，MouseButtonEventArgs） e）在System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler（Delegate genericHandler，Object genericTarget）At System.Windows.RoutedEventArgs.InvokeHandler（Delegate handler，Object target）At System.Windows.RoutedEventHandlerInfo.InvokeHandler（Object target，RoutedEventArgs routedEventArgs）At System.Windows.EventRoute.InvokeHandlersImpl（Object source，RoutedEventArgsArgs，Boolean reRaised）在System.Windows.UIElement.RaiseEventImpl（DependencyObject sender，RoutedEventArgs args）在System.Windows.UIElement.RaiseTrustedEvent（RoutedEventArgs args）处于System.Windows.UIElement。 RaiseEvent（RoutedEventAr gs args，布尔值信任）在System.Windows.Input.InputManager.ProcessStagingArea（）处于System.Windows.Input.InputManager.ProcessInput（InputEventArgs输入）
I'm working with VS 2015 on a WPF application using Entity Framework. In this application I have in one of my WPF window the possibility to serialize a canvas on which I got some custom controls.
Today I tried to add to one of my custom controls a new dependencyproperty which is an observablecollection which type is an entity (in my case a table called Formulas).
Normally it's not possible to serialize generic types.
So I added a new class to my app and used that in my code as property type.
public class AssignedFormulasCollection : ObservableCollection<Formulas> { public AssignedFormulasCollection() { } public AssignedFormulasCollection(List<Formulas> list) : base(list) { } }This is the code of the entity Formulas:
public partial class Formulas { public Formulas() { this.Formula_Attributes = new HashSet<Formula_Attributes>(); this.Formula_Field_Attributes = new HashSet<Formula_Field_Attributes>(); this.Input_Field_Formulas = new HashSet<Input_Field_Formulas>(); this.Stepfunctions = new HashSet<Stepfunctions>(); } public int formula_id { get; set; } public int description_id { get; set; } public string formula_name { get; set; } public string formula_version { get; set; } public string formula_expression { get; set; } public string formula_type { get; set; } public Nullable<float> result1 { get; set; } public Nullable<float> result2 { get; set; } public Nullable<float> result3 { get; set; } public Nullable<int> version { get; set; } public string changer { get; set; } public Nullable<System.DateTime> change_date { get; set; } public virtual Descriptions Descriptions { get; set; } public virtual ICollection<Formula_Attributes> Formula_Attributes { get; set; } public virtual ICollection<Formula_Field_Attributes> Formula_Field_Attributes { get; set; } public virtual ICollection<Input_Field_Formulas> Input_Field_Formulas { get; set; } public virtual ICollection<Stepfunctions> Stepfunctions { get; set; } }I serialize the canvas by this method:
public string SerializeControlToXaml(FrameworkElement element) { var elementToXaml = new StringBuilder(); var settings = new XmlWriterSettings(); settings.Indent = true; settings.OmitXmlDeclaration = true; var serializationManager = new XamlDesignerSerializationManager(XmlWriter.Create(elementToXaml, settings)); serializationManager.XamlWriterMode = XamlWriterMode.Expression; XamlWriter.Save(element, serializationManager); var xaml = elementToXaml.ToString(); return xaml; }But when I try to serialize the canvas with the custom controls I get the following error message:
System.Reflection.TargetInvocationException was not handled by user code. HResult = -2146232828 Message = The PropertyAccessorDescriptions for the System.Data.Entity.DynamicProxies.Formulas_CF5776A4E794BA378BEBDBE1E29E7967B4AACCF844AB5416006C852677145A0A object caused the following exception: The ObjectContext instance was discarded and can no longer be used for transactions that require a connection.
Source = System
StackTrace: At System.ComponentModel.ReflectPropertyDescriptor.GetValue (Object component) At System.Windows.Markup.Primitives.ElementProperty.get_Value () At System.Windows.Markup.Primitives.ElementPropertyBase.get_IsComposite () At System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces (ScopeScope, MarkupObject item, IValueSerializerContext context, Boolean lastWasString) At System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces (ScopeScope, MarkupObject item, IValueSerializerContext context, Boolean lastWasString) At System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces (ScopeScope, MarkupObject item, IValueSerializerContext context, Boolean lastWasString) At System.Windows.Markup.Primitives.MarkupWriter.RecordNamespaces (ScopeScope, MarkupObject item, IValueSerializerContext context, Boolean lastWasString) At System.Windows.Markup.Primitives.MarkupWriter.WriteItem (MarkupObject item) At System.Windows.Markup.Primitives.MarkupWriter.SaveAsXml (XmlWriter writer, MarkupObject item) At System.Windows.Markup.Primitives.MarkupWriter.SaveAsXml (XmlWriter writer, Object instance, XamlDesignerSerializationManager manager) At System.Windows.Markup.XamlWriter.Save (Object obj, XamlDesignerSerializationManager manager) At P16Common.XamlDeSerializer.SerializeControlToXaml (FrameworkElement element) in C: \ svn_checkout \ P16_RoeV \ Sourcen \ P16Admintool_develop \ P16Common \ XamlDeSerializer.cs: Line 50. At P16Common.CommonMethods.SerializeToXml (FrameworkElement designerGrid) to C: \ svn_checkout \ P16_RoeV \ Sourcen \ P16Admintool_develop \ P16Common \ CommonMethods.cs: Line 61. At P16Admintool.Helper.InputMaskHelper.UpdateInputMask (InputMasksView designerwindow) to C: \ svn_checkout \ P16_RoeV \ Resources \ P16Admintool_develop \ P16Admintool \ Helper \ InputMaskHelper.cs: Line 39. At P16Admintool.ViewModels.ChangeElementPropertiesViewModel.SetElementProperties () in C: \ svn_checkout \ P16_RoeV \ Sourcen \ P16Admintool_develop \ P16Admintool \ ViewModels \ ChangeElementPropertiesViewModel.cs: Line 152. For P16Admintool.Views.ChangeElementProperties.btn_set_properties_Click (Object sender, RoutedEventArgs e) in C: \ svn_checkout \ P16_RoeV \ Resources \ P16Admintool_develop \ P16Admintool \ Views \ ChangeElementProperties.xaml.cs: Line 77. At System.Windows.RoutedEventHandlerInfo.InvokeHandler (Object target, RoutedEventArgs routedEventArgs) At System.Windows.EventRoute.InvokeHandlersImpl (Object source, RoutedEventArgsArgs, Boolean reRaised) At System.Windows.UIElement.RaiseEventImpl (DependencyObject sender, RoutedEventArgs args) At System.Windows.UIElement.RaiseEvent (RoutedEventArgs e) At System.Windows.Controls.Primitives.ButtonBase.OnClick () At System.Windows.Controls.Button.OnClick () At System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp (MouseButtonEventArgs e) At System.Windows.UIElement.OnMouseLeftButtonUpThunk (Object sender, MouseButtonEventArgs e) At System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler (Delegate genericHandler, Object genericTarget) At System.Windows.RoutedEventArgs.InvokeHandler (Delegate handler, Object target) At System.Windows.RoutedEventHandlerInfo.InvokeHandler (Object target, RoutedEventArgs routedEventArgs) At System.Windows.EventRoute.InvokeHandlersImpl (Object source, RoutedEventArgsArgs, Boolean reRaised) At System.Windows.UIElement.ReRaiseEventAs (DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent) At System.Windows.UIElement.OnMouseUpThunk (Object sender, MouseButtonEventArgs e) At System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler (Delegate genericHandler, Object genericTarget) At System.Windows.RoutedEventArgs.InvokeHandler (Delegate handler, Object target) At System.Windows.RoutedEventHandlerInfo.InvokeHandler (Object target, RoutedEventArgs routedEventArgs) At System.Windows.EventRoute.InvokeHandlersImpl (Object source, RoutedEventArgsArgs, Boolean reRaised) At System.Windows.UIElement.RaiseEventImpl (DependencyObject sender, RoutedEventArgs args) At System.Windows.UIElement.RaiseTrustedEvent (RoutedEventArgs args) At System.Windows.UIElement.RaiseEvent (RoutedEventArgs args, Boolean trusted) At System.Windows.Input.InputManager.ProcessStagingArea () At System.Windows.Input.InputManager.ProcessInput (InputEventArgs input)
最满意答案
延迟加载和序列化不能很好地混合，请参阅以下有关https://msdn.microsoft.com/en-us/library/jj574232(v=vs.113).aspx的文章。
在您的情况下，您可能需要急切地加载所有依赖项，即以下属性的集合。 就像你说的那样，首先从Descriptions属性开始可能是一个好主意。
public virtual Descriptions Descriptions { get; set; } public virtual ICollection<Formula_Attributes> Formula_Attributes { get; set; } public virtual ICollection<Formula_Field_Attributes> Formula_Field_Attributes { get; set; } public virtual ICollection<Input_Field_Formulas> Input_Field_Formulas { get; set; } public virtual ICollection<Stepfunctions> Stepfunctions { get; set; }每当您调用上下文加载Formulas您将需要在Descriptions和任何其他延迟加载的集合上调用.Include(..) 。
Lazy loading and serialization do not mix well, see the following article on why https://msdn.microsoft.com/en-us/library/jj574232(v=vs.113).aspx.
In your case you might need to eagerly load all the dependencies i.e. collections of the following properties. And like you said, it might be a good idea to start with the Descriptions property first.
public virtual Descriptions Descriptions { get; set; } public virtual ICollection<Formula_Attributes> Formula_Attributes { get; set; } public virtual ICollection<Formula_Field_Attributes> Formula_Field_Attributes { get; set; } public virtual ICollection<Input_Field_Formulas> Input_Field_Formulas { get; set; } public virtual ICollection<Stepfunctions> Stepfunctions { get; set; }Whenever you call your context to load Formulas you will need to call .Include(..) on the Descriptions and any other lazy loaded collections.
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