如何使用EF 4.x DbContext生成器获取属性更改通知

Question

我正在使用Entity Framework 4.3，因此我使用DbContext Generator来创建上下文和实体类。

使用默认的EF 4代码生成器模板，实体类实现INotifyPropertyChanged，并在属性设置器中添加Changing和Changed部分方法。

当我使用EF 4.x DbContext生成器时，如下图所示，实体类更轻，并且不包括任何跟踪属性更改的方法。

以下是一个例子：

//------------------------------------------------------------------------------
// <auto-generated>
//    This code was generated from a template.
//
//    Manual changes to this file may cause unexpected behavior in your application.
//    Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Collections.Generic;

namespace SomeNamespace
{
    public partial class SomeTable
    {
        public SomeTable()
        {
            this.Children = new HashSet<Child>();
        }

        public long parent_id { get; set; }
        public long id { get; set; }
        public string filename { get; set; }
        public byte[] file_blob { get; set; }

        public virtual Parent Parent { get; set; }
        public virtual ICollection<Child> Children { get; set; }
    }
}

我必须错过一个重要的难题，但我的搜索没有结果。所以我的问题是：如何使用EF 4.3生成包含属性更改通知的类型？

修改

我完全同意@derape的答案;但我很好奇为什么当EF 4默认代码生成模板已经有钩子时，我需要更改.tt文件。我的意思是什么时候绑定到WPF DependencyProperty'？如果没有INotifyPropertyChanged，命令对一堆对象中的一组属性所做的更改将不会反映在UI中。我错过了什么？

Answer 1

我最近偶然发现了这个问题，我编辑了我的Entity.tt来实现以下更改，快速补丁但效果很好..

将以下内容添加到CodeStringGenerator类

public string EntityClassOpening(EntityType entity)
{
    return string.Format(
        CultureInfo.InvariantCulture,
        "{0} {1}partial class {2}{3} : {4}",
        Accessibility.ForType(entity),
        _code.SpaceAfter(_code.AbstractOption(entity)),
        _code.Escape(entity),
        _code.StringBefore(" : ", _typeMapper.GetTypeName(entity.BaseType)),
        "INotifyPropertyChanged");
}


public string Property(EdmProperty edmProperty)
{
    return string.Format(
        CultureInfo.InvariantCulture,
        "{0} {1} {2} {{ {3}{6} {4}{5} }}",
        Accessibility.ForProperty(edmProperty),
        _typeMapper.GetTypeName(edmProperty.TypeUsage),
        _code.Escape(edmProperty),
        _code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
        _code.SpaceAfter(Accessibility.ForSetter(edmProperty)),
        "set { _"+_code.Escape(edmProperty).ToLower()+" = value; OnPropertyChanged(\""+_code.Escape(edmProperty)+"\");}",
        "get { return _"+_code.Escape(edmProperty).ToLower()+"; }");

}
public string Private(EdmProperty edmProperty) {
    return string.Format(
        CultureInfo.InvariantCulture,
        "{0} {1} _{2};",
        "private",
        _typeMapper.GetTypeName(edmProperty.TypeUsage),
        _code.Escape(edmProperty).ToLower());

}

将以下内容添加到生成器

using System.ComponentModel;
<#=codeStringGenerator.EntityClassOpening(entity)#>
{
<#
var propertiesWithDefaultValues = typeMapper.GetPropertiesWithDefaultValues(entity);
var collectionNavigationProperties = typeMapper.GetCollectionNavigationProperties(entity);
var complexProperties = typeMapper.GetComplexProperties(entity);
#>

public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}

进一步下降

foreach (var edmProperty in simpleProperties)
{
#>
<#=codeStringGenerator.Private(edmProperty)#>
    <#=codeStringGenerator.Property(edmProperty)#>
<#
}


foreach(var complexProperty in complexProperties)
{
#>
<#=codeStringGenerator.Private(complexProperty)#>
    <#=codeStringGenerator.Property(complexProperty)#>
<#
}

Answer 2

我在Anders答案中创建了一个变体，但有以下不同之处：

• 对Entity.tt文件的更改较少
• 为INotifyPropertyChanged实现使用基类（方便引入其他常用功能）
• 生成的模型类中的清洁代码布局

所以我的步骤是：

为要扩展的模型类创建基类：

public abstract class BaseModel : INotifyPropertyChanged
{
    protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName] String propertyName = null)
    {
        if (object.Equals(storage, value)) return false;

        storage = value;
        this.OnPropertyChanged(propertyName);
        return true;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

感谢Juan Pable Gomez的建议改进！我喜欢你的改进，即使其他评论者没有：）

将Entity.tt文件中的EntityClassOpening方法更新为以下内容：

public string EntityClassOpening(EntityType entity)
{
    return string.Format(
        CultureInfo.InvariantCulture,
        "{0} {1}partial class {2}{3}",
        Accessibility.ForType(entity),
        _code.SpaceAfter(_code.AbstractOption(entity)),
        _code.Escape(entity),
        _code.StringBefore(" : ", string.IsNullOrEmpty(_typeMapper.GetTypeName(entity.BaseType)) ? "BaseModel" : _typeMapper.GetTypeName(entity.BaseType)));
}

找到一行：

<#=Accessibility.ForType(complex)#> partial class <#=code.Escape(complex)#>

并将其更新为：

<#=Accessibility.ForType(complex)#> partial class <#=code.Escape(complex)#> : BaseModel

感谢Manolo！

将Entity.tt文件中的Property方法更新为以下内容：

public string Property(EdmProperty edmProperty)
{
    return string.Format(
        CultureInfo.InvariantCulture,
        "private {1} {3};\r\n"+
        "\t{0} {1} {2} \r\n" +
        "\t{{ \r\n" +
            "\t\t{4}get {{ return {3}; }} \r\n" +
            "\t\t{5}set {{ SetProperty(ref {3}, value); }} \r\n" + 
        "\t}}\r\n",
        Accessibility.ForProperty(edmProperty),
        _typeMapper.GetTypeName(edmProperty.TypeUsage),
        _code.Escape(edmProperty),
        "_" + Char.ToLowerInvariant(_code.Escape(edmProperty)[0]) + _code.Escape(edmProperty).Substring(1),
        _code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
        _code.SpaceAfter(Accessibility.ForSetter(edmProperty)));
}

你已经完成了！现在您的模型类将如下所示：

public partial class User : BaseModel
{
    private int _id;
    public int Id 
    { 
        get { return _id; } 
        set { SetProperty(ref _id,value);}
    }

    private string _name;
    public string Name 
    { 
        get { return _name; } 
        set { SetProperty(ref _name , value); }
    }

如果您能看到其他改进，请随时（尝试）编辑此解决方案。

Answer 3

我试图编辑 Brian Hinchey解决方案但是EDIT被拒绝了。然后我在这里发布我的addapts。

此解决方案为每个属性Setter生成较少的代码，利用 CallerMemberName属性。

注意：我正在使用EF 6.1，它运行良好。

BaseClass现在看起来像这样。

public abstract class BaseModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName] String propertyName = null)
    {
        if (object.Equals(storage, value)) return false;

        storage = value;
        this.OnPropertyChanged(propertyName);
        return true;
    }


    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var eventHandler = this.PropertyChanged;
        if (eventHandler != null)
        {
            eventHandler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

更新Entity.tt中的EntityClassOpening方法完全和Brian一样：

public string EntityClassOpening(EntityType entity)
{
    return string.Format(
        CultureInfo.InvariantCulture,
        "{0} {1}partial class {2}{3}",
        Accessibility.ForType(entity),
        _code.SpaceAfter(_code.AbstractOption(entity)),
        _code.Escape(entity),
        _code.StringBefore(" : ", string.IsNullOrEmpty(_typeMapper.GetTypeName(entity.BaseType)) ? "BaseModel" : _typeMapper.GetTypeName(entity.BaseType)));
}

正如布莱恩所说，记得改变：

<#=Accessibility.ForType(complex)#> partial class <#=code.Escape(complex)#>
FOR 
<#=Accessibility.ForType(complex)#> partial class <#=code.Escape(complex)#> : BaseModel

我的最后一项更改是属性方法

public string Property(EdmProperty edmProperty)
{
    return string.Format(
        CultureInfo.InvariantCulture,
        "private {1} {3};\r\n"+
        "\t{0} {1} {2} \r\n" +
        "\t{{ \r\n" +
            "\t\t{4}get {{ return {3}; }} \r\n" +
            "\t\t{5}set {{ SetProperty(ref {3}, value); }} \r\n" + 
        "\t}}\r\n",
        Accessibility.ForProperty(edmProperty),
        _typeMapper.GetTypeName(edmProperty.TypeUsage),
        _code.Escape(edmProperty),
        "_" + Char.ToLowerInvariant(_code.Escape(edmProperty)[0]) + _code.Escape(edmProperty).Substring(1),
        _code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
        _code.SpaceAfter(Accessibility.ForSetter(edmProperty)));
}

最后这个课程看起来像是：

public partial class User : BaseModel
{
    private int _id;
    public int Id 
    { 
        get { return _id; } 
        set { SetProperty(ref _id , value);} 
    }

    private string _name;
    public string Name 
    { 
        get { return _name; } 
        set { SetProperty(ref _name , value);}
    } 
}

这使得生成的clases更轻。

最近我正在使用 PropertyChanged.Fody 库，但原因不明（至少对我而言）它有时无法正常工作。这就是我降落在这里的原因。这个解决方案（布莱恩的解决方案）每次都有效。

Answer 4

以上Anders的解决方案有效，但我在此过程中发现了一些问题：

在步骤1中，它说“将以下内容添加到CodeStringGenerator类”，只能添加“public string Private（...”函数，因为其他两个已经存在。所以，你需要找到它们并替换它们这两个函数不会添加它们，否则你会得到错误。要找到你需要放置它们的确切位置，搜索“public class CodeStringGenerator”，并查找下面的函数。

在步骤2“将以下内容添加到生成器”中，您只需要添加“using System.ComponentModel”行，以及来自（包括）“public event PropertyChangedEventHandler ...”的行。同样，其他行已经存在，你会发现它们位于.tt文件的顶部附近。

在第3步“又向下”，这两个“foreach”循环也已经存在，因此必须更换它们而不是添加它们。最终每个foreach循环只添加一行，“＆lt;＃= codeStringGenerator.Private（edmProperty）＃＆gt;”和“＆lt;＃= codeStringGenerator.Private（complexProperty）＃＆gt;”分别在每个循环中。

另外，不要更换错误的循环，在需要替换的循环之上还有两个额外的循环，它们循环通过相同的对象...确保替换正确的循环： - ）

我想我会提到这个，因为作为MVVM / EF新手（曾经使用过NHibernate）我不得不对它进行调整才能正常工作。

Answer 5

这取决于你想要做什么。如果您只想实现自定义属性/方法，则可以使用部分类的功能。 如果你想在实体设计器中更改属性的setter / getter，则必须调整dbContext生成器模板文件。这是一个T4模板。

Answer 6

我创建了以下内容用于EF 6.1.2，但测试相当有限，因此使用风险自负。

<#@ template language="C#" debug="false" hostspecific="true"#>
<#@ include file="EF6.Utility.CS.ttinclude"#><#@ 
 output extension=".cs"#><#

const string inputFile = @"Model.edmx";
var textTransform = DynamicTextTransformation.Create(this);
var code = new CodeGenerationTools(this);
var ef = new MetadataTools(this);
var typeMapper = new TypeMapper(code, ef, textTransform.Errors);
var fileManager = EntityFrameworkTemplateFileManager.Create(this);
var itemCollection = new EdmMetadataLoader(textTransform.Host, textTransform.Errors).CreateEdmItemCollection(inputFile);
var codeStringGenerator = new CodeStringGenerator(code, typeMapper, ef);

if (!typeMapper.VerifyCaseInsensitiveTypeUniqueness(typeMapper.GetAllGlobalItems(itemCollection), inputFile))
{
    return string.Empty;
}

WriteHeader(codeStringGenerator, fileManager);

foreach (var entity in typeMapper.GetItemsToGenerate<EntityType>(itemCollection))
{
    fileManager.StartNewFile(entity.Name + ".cs");
    BeginNamespace(code);
#>
<#=codeStringGenerator.UsingDirectives(inHeader: false)#>
<#=codeStringGenerator.EntityClassOpening(entity)#>
{
<#
    var propertiesWithDefaultValues = typeMapper.GetPropertiesWithDefaultValues(entity);
    var collectionNavigationProperties = typeMapper.GetCollectionNavigationProperties(entity);
    var complexProperties = typeMapper.GetComplexProperties(entity);

    if (propertiesWithDefaultValues.Any() || collectionNavigationProperties.Any() || complexProperties.Any())
    {
#>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public <#=code.Escape(entity)#>()
    {
<#
        foreach (var edmProperty in propertiesWithDefaultValues)
        {
#>
        this.<#=code.Escape(edmProperty)#> = <#=typeMapper.CreateLiteral(edmProperty.DefaultValue)#>;
<#
        }

        foreach (var navigationProperty in collectionNavigationProperties)
        {
#>
        this.<#=code.Escape(navigationProperty)#> = new HashSet<<#=typeMapper.GetTypeName(navigationProperty.ToEndMember.GetEntityType())#>>();
<#
        }

        foreach (var complexProperty in complexProperties)
        {
#>
        this.<#=code.Escape(complexProperty)#> = new <#=typeMapper.GetTypeName(complexProperty.TypeUsage)#>();
<#
        }
#>
    }

<#
    }

    var simpleProperties = typeMapper.GetSimpleProperties(entity);
    if (simpleProperties.Any())
    {
        foreach (var edmProperty in simpleProperties)
        {
#>
    <#=codeStringGenerator.Property(edmProperty)#>
<#
        }
    }

    if (complexProperties.Any())
    {
#>

<#
        foreach(var complexProperty in complexProperties)
        {
#>
    <#=codeStringGenerator.Property(complexProperty)#>
<#
        }
    }

    var navigationProperties = typeMapper.GetNavigationProperties(entity);
    if (navigationProperties.Any())
    {
#>

<#
        foreach (var navigationProperty in navigationProperties)
        {
            if (navigationProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many)
            {
#>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
<#
            }
#>
    <#=codeStringGenerator.NavigationProperty(navigationProperty)#>
<#
        }
    }
#>

    #region INotifyPropertyChanged Members
    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
    {
        OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
    }

    protected virtual void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        WhenPropertyChanged(e);

        if (PropertyChanged != null)
        {
            PropertyChanged(this, e);
        }
    }

    partial void WhenPropertyChanged(PropertyChangedEventArgs e);
    #endregion
}
<#
    EndNamespace(code);
}

foreach (var complex in typeMapper.GetItemsToGenerate<ComplexType>(itemCollection))
{
    fileManager.StartNewFile(complex.Name + ".cs");
    BeginNamespace(code);
#>
<#=codeStringGenerator.UsingDirectives(inHeader: false, includeCollections: false)#>
<#=Accessibility.ForType(complex)#> partial class <#=code.Escape(complex)#>
{
<#
    var complexProperties = typeMapper.GetComplexProperties(complex);
    var propertiesWithDefaultValues = typeMapper.GetPropertiesWithDefaultValues(complex);

    if (propertiesWithDefaultValues.Any() || complexProperties.Any())
    {
#>
    public <#=code.Escape(complex)#>()
    {
<#
        foreach (var edmProperty in propertiesWithDefaultValues)
        {
#>
        this.<#=code.Escape(edmProperty)#> = <#=typeMapper.CreateLiteral(edmProperty.DefaultValue)#>;
<#
        }

        foreach (var complexProperty in complexProperties)
        {
#>
        this.<#=code.Escape(complexProperty)#> = new <#=typeMapper.GetTypeName(complexProperty.TypeUsage)#>();
<#
        }
#>
    }

<#
    }

    var simpleProperties = typeMapper.GetSimpleProperties(complex);
    if (simpleProperties.Any())
    {
        foreach(var edmProperty in simpleProperties)
        {
#>
    <#=codeStringGenerator.Property(edmProperty)#>
<#
        }
    }

    if (complexProperties.Any())
    {
#>

<#
        foreach(var edmProperty in complexProperties)
        {
#>
    <#=codeStringGenerator.Property(edmProperty)#>
<#
        }
    }
#>
}
<#
    EndNamespace(code);
}

foreach (var enumType in typeMapper.GetEnumItemsToGenerate(itemCollection))
{
    fileManager.StartNewFile(enumType.Name + ".cs");
    BeginNamespace(code);
#>
<#=codeStringGenerator.UsingDirectives(inHeader: false, includeCollections: false)#>
<#
    if (typeMapper.EnumIsFlags(enumType))
    {
#>
[Flags]
<#
    }
#>
<#=codeStringGenerator.EnumOpening(enumType)#>
{
<#
    var foundOne = false;

    foreach (MetadataItem member in typeMapper.GetEnumMembers(enumType))
    {
        foundOne = true;
#>
    <#=code.Escape(typeMapper.GetEnumMemberName(member))#> = <#=typeMapper.GetEnumMemberValue(member)#>,
<#
    }

    if (foundOne)
    {
        this.GenerationEnvironment.Remove(this.GenerationEnvironment.Length - 3, 1);
    }
#>
}
<#
    EndNamespace(code);
}

fileManager.Process();

#>
<#+

public void WriteHeader(CodeStringGenerator codeStringGenerator, EntityFrameworkTemplateFileManager fileManager)
{
    fileManager.StartHeader();
#>
//------------------------------------------------------------------------------
// <auto-generated>
// <#=CodeGenerationTools.GetResourceString("Template_GeneratedCodeCommentLine1")#>
//
// <#=CodeGenerationTools.GetResourceString("Template_GeneratedCodeCommentLine2")#>
// <#=CodeGenerationTools.GetResourceString("Template_GeneratedCodeCommentLine3")#>
// </auto-generated>
//------------------------------------------------------------------------------
<#=codeStringGenerator.UsingDirectives(inHeader: true)#>
<#+
    fileManager.EndBlock();
}

public void BeginNamespace(CodeGenerationTools code)
{
    var codeNamespace = code.VsNamespaceSuggestion();
    if (!String.IsNullOrEmpty(codeNamespace))
    {
#>
namespace <#=code.EscapeNamespace(codeNamespace)#>
{
<#+
        PushIndent("    ");
    }
}

public void EndNamespace(CodeGenerationTools code)
{
    if (!String.IsNullOrEmpty(code.VsNamespaceSuggestion()))
    {
        PopIndent();
#>
}
<#+
    }
}

public const string TemplateId = "CSharp_DbContext_Types_EF6";

public class CodeStringGenerator
{
    private readonly CodeGenerationTools _code;
    private readonly TypeMapper _typeMapper;
    private readonly MetadataTools _ef;

    public CodeStringGenerator(CodeGenerationTools code, TypeMapper typeMapper, MetadataTools ef)
    {
        ArgumentNotNull(code, "code");
        ArgumentNotNull(typeMapper, "typeMapper");
        ArgumentNotNull(ef, "ef");

        _code = code;
        _typeMapper = typeMapper;
        _ef = ef;
    }

    public string Property(EdmProperty edmProperty)
    {
        StringBuilder propertyCode = new StringBuilder();
        propertyCode.AppendFormat("private {0} _{1};",_typeMapper.GetTypeName(edmProperty.TypeUsage), _code.Escape(edmProperty));
        propertyCode.AppendFormat(
            CultureInfo.InvariantCulture,
            "{0} {1} {2} {{ {3}get{{ return _{2};}} {4}set{{if(_{2} != value){{_{2} = value; OnPropertyChanged(\"{2}\");}}}}}}",
            Accessibility.ForProperty(edmProperty),
            _typeMapper.GetTypeName(edmProperty.TypeUsage),
            _code.Escape(edmProperty),
            _code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
            _code.SpaceAfter(Accessibility.ForSetter(edmProperty)));

        return propertyCode.ToString();
    }

    public string NavigationProperty(NavigationProperty navProp)
    {
        var endType = _typeMapper.GetTypeName(navProp.ToEndMember.GetEntityType());
        return string.Format(
            CultureInfo.InvariantCulture,
            "{0} {1} {2} {{ {3}get; {4}set; }}",
            AccessibilityAndVirtual(Accessibility.ForNavigationProperty(navProp)),
            navProp.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many ? ("ICollection<" + endType + ">") : endType,
            _code.Escape(navProp),
            _code.SpaceAfter(Accessibility.ForGetter(navProp)),
            _code.SpaceAfter(Accessibility.ForSetter(navProp)));
    }

    public string AccessibilityAndVirtual(string accessibility)
    {
        return accessibility + (accessibility != "private" ? " virtual" : "");
    }

    public string EntityClassOpening(EntityType entity)
    {
        return string.Format(
            CultureInfo.InvariantCulture,
            "{0} {1}partial class {2} : INotifyPropertyChanged{3}",
            Accessibility.ForType(entity),
            _code.SpaceAfter(_code.AbstractOption(entity)),
            _code.Escape(entity),
            _code.StringBefore(", ", _typeMapper.GetTypeName(entity.BaseType)));
    }

    public string EnumOpening(SimpleType enumType)
    {
        return string.Format(
            CultureInfo.InvariantCulture,
            "{0} enum {1} : {2}",
            Accessibility.ForType(enumType),
            _code.Escape(enumType),
            _code.Escape(_typeMapper.UnderlyingClrType(enumType)));
        }

    public void WriteFunctionParameters(EdmFunction edmFunction, Action<string, string, string, string> writeParameter)
    {
        var parameters = FunctionImportParameter.Create(edmFunction.Parameters, _code, _ef);
        foreach (var parameter in parameters.Where(p => p.NeedsLocalVariable))
        {
            var isNotNull = parameter.IsNullableOfT ? parameter.FunctionParameterName + ".HasValue" : parameter.FunctionParameterName + " != null";
            var notNullInit = "new ObjectParameter(\"" + parameter.EsqlParameterName + "\", " + parameter.FunctionParameterName + ")";
            var nullInit = "new ObjectParameter(\"" + parameter.EsqlParameterName + "\", typeof(" + TypeMapper.FixNamespaces(parameter.RawClrTypeName) + "))";
            writeParameter(parameter.LocalVariableName, isNotNull, notNullInit, nullInit);
        }
    }

    public string ComposableFunctionMethod(EdmFunction edmFunction, string modelNamespace)
    {
        var parameters = _typeMapper.GetParameters(edmFunction);

        return string.Format(
            CultureInfo.InvariantCulture,
            "{0} IQueryable<{1}> {2}({3})",
            AccessibilityAndVirtual(Accessibility.ForMethod(edmFunction)),
            _typeMapper.GetTypeName(_typeMapper.GetReturnType(edmFunction), modelNamespace),
            _code.Escape(edmFunction),
            string.Join(", ", parameters.Select(p => TypeMapper.FixNamespaces(p.FunctionParameterType) + " " + p.FunctionParameterName).ToArray()));
    }

    public string ComposableCreateQuery(EdmFunction edmFunction, string modelNamespace)
    {
        var parameters = _typeMapper.GetParameters(edmFunction);

        return string.Format(
            CultureInfo.InvariantCulture,
            "return ((IObjectContextAdapter)this).ObjectContext.CreateQuery<{0}>(\"[{1}].[{2}]({3})\"{4});",
            _typeMapper.GetTypeName(_typeMapper.GetReturnType(edmFunction), modelNamespace),
            edmFunction.NamespaceName,
            edmFunction.Name,
            string.Join(", ", parameters.Select(p => "@" + p.EsqlParameterName).ToArray()),
            _code.StringBefore(", ", string.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray())));
    }

    public string FunctionMethod(EdmFunction edmFunction, string modelNamespace, bool includeMergeOption)
    {
        var parameters = _typeMapper.GetParameters(edmFunction);
        var returnType = _typeMapper.GetReturnType(edmFunction);

        var paramList = String.Join(", ", parameters.Select(p => TypeMapper.FixNamespaces(p.FunctionParameterType) + " " + p.FunctionParameterName).ToArray());
        if (includeMergeOption)
        {
            paramList = _code.StringAfter(paramList, ", ") + "MergeOption mergeOption";
        }

        return string.Format(
            CultureInfo.InvariantCulture,
            "{0} {1} {2}({3})",
            AccessibilityAndVirtual(Accessibility.ForMethod(edmFunction)),
            returnType == null ? "int" : "ObjectResult<" + _typeMapper.GetTypeName(returnType, modelNamespace) + ">",
            _code.Escape(edmFunction),
            paramList);
    }

    public string ExecuteFunction(EdmFunction edmFunction, string modelNamespace, bool includeMergeOption)
    {
        var parameters = _typeMapper.GetParameters(edmFunction);
        var returnType = _typeMapper.GetReturnType(edmFunction);

        var callParams = _code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()));
        if (includeMergeOption)
        {
            callParams = ", mergeOption" + callParams;
        }

        return string.Format(
            CultureInfo.InvariantCulture,
            "return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction{0}(\"{1}\"{2});",
            returnType == null ? "" : "<" + _typeMapper.GetTypeName(returnType, modelNamespace) + ">",
            edmFunction.Name,
            callParams);
    }

    public string DbSet(EntitySet entitySet)
    {
        return string.Format(
            CultureInfo.InvariantCulture,
            "{0} virtual DbSet<{1}> {2} {{ get; set; }}",
            Accessibility.ForReadOnlyProperty(entitySet),
            _typeMapper.GetTypeName(entitySet.ElementType),
            _code.Escape(entitySet));
    }

    public string UsingDirectives(bool inHeader, bool includeCollections = true)
    {
        return inHeader == string.IsNullOrEmpty(_code.VsNamespaceSuggestion())
            ? string.Format(
                CultureInfo.InvariantCulture,
                "{0}using System;" + Environment.NewLine + 
                "using System.ComponentModel;{1}" +
                "{2}",
                inHeader ? Environment.NewLine : "",
                includeCollections ? (Environment.NewLine + "using System.Collections.Generic;") : "",
                inHeader ? "" : Environment.NewLine)
            : "";
    }
}

public class TypeMapper
{
    private const string ExternalTypeNameAttributeName = @"http://schemas.microsoft.com/ado/2006/04/codegeneration:ExternalTypeName";

    private readonly System.Collections.IList _errors;
    private readonly CodeGenerationTools _code;
    private readonly MetadataTools _ef;

    public TypeMapper(CodeGenerationTools code, MetadataTools ef, System.Collections.IList errors)
    {
        ArgumentNotNull(code, "code");
        ArgumentNotNull(ef, "ef");
        ArgumentNotNull(errors, "errors");

        _code = code;
        _ef = ef;
        _errors = errors;
    }

    public static string FixNamespaces(string typeName)
    {
        return typeName.Replace("System.Data.Spatial.", "System.Data.Entity.Spatial.");
    }

    public string GetTypeName(TypeUsage typeUsage)
    {
        return typeUsage == null ? null : GetTypeName(typeUsage.EdmType, _ef.IsNullable(typeUsage), modelNamespace: null);
    }

    public string GetTypeName(EdmType edmType)
    {
        return GetTypeName(edmType, isNullable: null, modelNamespace: null);
    }

    public string GetTypeName(TypeUsage typeUsage, string modelNamespace)
    {
        return typeUsage == null ? null : GetTypeName(typeUsage.EdmType, _ef.IsNullable(typeUsage), modelNamespace);
    }

    public string GetTypeName(EdmType edmType, string modelNamespace)
    {
        return GetTypeName(edmType, isNullable: null, modelNamespace: modelNamespace);
    }

    public string GetTypeName(EdmType edmType, bool? isNullable, string modelNamespace)
    {
        if (edmType == null)
        {
            return null;
        }

        var collectionType = edmType as CollectionType;
        if (collectionType != null)
        {
            return String.Format(CultureInfo.InvariantCulture, "ICollection<{0}>", GetTypeName(collectionType.TypeUsage, modelNamespace));
        }

        var typeName = _code.Escape(edmType.MetadataProperties
                                .Where(p => p.Name == ExternalTypeNameAttributeName)
                                .Select(p => (string)p.Value)
                                .FirstOrDefault())
            ?? (modelNamespace != null && edmType.NamespaceName != modelNamespace ?
                _code.CreateFullName(_code.EscapeNamespace(edmType.NamespaceName), _code.Escape(edmType)) :
                _code.Escape(edmType));

        if (edmType is StructuralType)
        {
            return typeName;
        }

        if (edmType is SimpleType)
        {
            var clrType = UnderlyingClrType(edmType);
            if (!IsEnumType(edmType))
            {
                typeName = _code.Escape(clrType);
            }

            typeName = FixNamespaces(typeName);

            return clrType.IsValueType && isNullable == true ?
                String.Format(CultureInfo.InvariantCulture, "Nullable<{0}>", typeName) :
                typeName;
        }

        throw new ArgumentException("edmType");
    }

    public Type UnderlyingClrType(EdmType edmType)
    {
        ArgumentNotNull(edmType, "edmType");

        var primitiveType = edmType as PrimitiveType;
        if (primitiveType != null)
        {
            return primitiveType.ClrEquivalentType;
        }

        if (IsEnumType(edmType))
        {
            return GetEnumUnderlyingType(edmType).ClrEquivalentType;
        }

        return typeof(object);
    }

    public object GetEnumMemberValue(MetadataItem enumMember)
    {
        ArgumentNotNull(enumMember, "enumMember");

        var valueProperty = enumMember.GetType().GetProperty("Value");
        return valueProperty == null ? null : valueProperty.GetValue(enumMember, null);
    }

    public string GetEnumMemberName(MetadataItem enumMember)
    {
        ArgumentNotNull(enumMember, "enumMember");

        var nameProperty = enumMember.GetType().GetProperty("Name");
        return nameProperty == null ? null : (string)nameProperty.GetValue(enumMember, null);
    }

    public System.Collections.IEnumerable GetEnumMembers(EdmType enumType)
    {
        ArgumentNotNull(enumType, "enumType");

        var membersProperty = enumType.GetType().GetProperty("Members");
        return membersProperty != null 
            ? (System.Collections.IEnumerable)membersProperty.GetValue(enumType, null)
            : Enumerable.Empty<MetadataItem>();
    }

    public bool EnumIsFlags(EdmType enumType)
    {
        ArgumentNotNull(enumType, "enumType");

        var isFlagsProperty = enumType.GetType().GetProperty("IsFlags");
        return isFlagsProperty != null && (bool)isFlagsProperty.GetValue(enumType, null);
    }

    public bool IsEnumType(GlobalItem edmType)
    {
        ArgumentNotNull(edmType, "edmType");

        return edmType.GetType().Name == "EnumType";
    }

    public PrimitiveType GetEnumUnderlyingType(EdmType enumType)
    {
        ArgumentNotNull(enumType, "enumType");

        return (PrimitiveType)enumType.GetType().GetProperty("UnderlyingType").GetValue(enumType, null);
    }

    public string CreateLiteral(object value)
    {
        if (value == null || value.GetType() != typeof(TimeSpan))
        {
            return _code.CreateLiteral(value);
        }

        return string.Format(CultureInfo.InvariantCulture, "new TimeSpan({0})", ((TimeSpan)value).Ticks);
    }

    public bool VerifyCaseInsensitiveTypeUniqueness(IEnumerable<string> types, string sourceFile)
    {
        ArgumentNotNull(types, "types");
        ArgumentNotNull(sourceFile, "sourceFile");

        var hash = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
        if (types.Any(item => !hash.Add(item)))
        {
            _errors.Add(
                new CompilerError(sourceFile, -1, -1, "6023",
                    String.Format(CultureInfo.CurrentCulture, CodeGenerationTools.GetResourceString("Template_CaseInsensitiveTypeConflict"))));
            return false;
        }
        return true;
    }

    public IEnumerable<SimpleType> GetEnumItemsToGenerate(IEnumerable<GlobalItem> itemCollection)
    {
        return GetItemsToGenerate<SimpleType>(itemCollection)
            .Where(e => IsEnumType(e));
    }

    public IEnumerable<T> GetItemsToGenerate<T>(IEnumerable<GlobalItem> itemCollection) where T: EdmType
    {
        return itemCollection
            .OfType<T>()
            .Where(i => !i.MetadataProperties.Any(p => p.Name == ExternalTypeNameAttributeName))
            .OrderBy(i => i.Name);
    }

    public IEnumerable<string> GetAllGlobalItems(IEnumerable<GlobalItem> itemCollection)
    {
        return itemCollection
            .Where(i => i is EntityType || i is ComplexType || i is EntityContainer || IsEnumType(i))
            .Select(g => GetGlobalItemName(g));
    }

    public string GetGlobalItemName(GlobalItem item)
    {
        if (item is EdmType)
        {
            return ((EdmType)item).Name;
        }
        else
        {
            return ((EntityContainer)item).Name;
        }
    }

    public IEnumerable<EdmProperty> GetSimpleProperties(EntityType type)
    {
        return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type);
    }

    public IEnumerable<EdmProperty> GetSimpleProperties(ComplexType type)
    {
        return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type);
    }

    public IEnumerable<EdmProperty> GetComplexProperties(EntityType type)
    {
        return type.Properties.Where(p => p.TypeUsage.EdmType is ComplexType && p.DeclaringType == type);
    }

    public IEnumerable<EdmProperty> GetComplexProperties(ComplexType type)
    {
        return type.Properties.Where(p => p.TypeUsage.EdmType is ComplexType && p.DeclaringType == type);
    }

    public IEnumerable<EdmProperty> GetPropertiesWithDefaultValues(EntityType type)
    {
        return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type && p.DefaultValue != null);
    }

    public IEnumerable<EdmProperty> GetPropertiesWithDefaultValues(ComplexType type)
    {
        return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type && p.DefaultValue != null);
    }

    public IEnumerable<NavigationProperty> GetNavigationProperties(EntityType type)
    {
        return type.NavigationProperties.Where(np => np.DeclaringType == type);
    }

    public IEnumerable<NavigationProperty> GetCollectionNavigationProperties(EntityType type)
    {
        return type.NavigationProperties.Where(np => np.DeclaringType == type && np.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many);
    }

    public FunctionParameter GetReturnParameter(EdmFunction edmFunction)
    {
        ArgumentNotNull(edmFunction, "edmFunction");

        var returnParamsProperty = edmFunction.GetType().GetProperty("ReturnParameters");
        return returnParamsProperty == null
            ? edmFunction.ReturnParameter
            : ((IEnumerable<FunctionParameter>)returnParamsProperty.GetValue(edmFunction, null)).FirstOrDefault();
    }

    public bool IsComposable(EdmFunction edmFunction)
    {
        ArgumentNotNull(edmFunction, "edmFunction");

        var isComposableProperty = edmFunction.GetType().GetProperty("IsComposableAttribute");
        return isComposableProperty != null && (bool)isComposableProperty.GetValue(edmFunction, null);
    }

    public IEnumerable<FunctionImportParameter> GetParameters(EdmFunction edmFunction)
    {
        return FunctionImportParameter.Create(edmFunction.Parameters, _code, _ef);
    }

    public TypeUsage GetReturnType(EdmFunction edmFunction)
    {
        var returnParam = GetReturnParameter(edmFunction);
        return returnParam == null ? null : _ef.GetElementType(returnParam.TypeUsage);
    }

    public bool GenerateMergeOptionFunction(EdmFunction edmFunction, bool includeMergeOption)
    {
        var returnType = GetReturnType(edmFunction);
        return !includeMergeOption && returnType != null && returnType.EdmType.BuiltInTypeKind == BuiltInTypeKind.EntityType;
    }
}

public static void ArgumentNotNull<T>(T arg, string name) where T : class
{
    if (arg == null)
    {
        throw new ArgumentNullException(name);
    }
}
#>

Answer 7

我使用Visual Basic并倾向于享受重构遗留和非分层体系结构。

所以，我已经使用上面的答案但在Entity Framework 6.1.3和.net 4.6.1中解决了如何做到这一点。

我已经从其他人给出的答案中翻译过来，所以我只能对今晚我已经完成的重新发现和翻译工作表示赞赏。

这个项目非常小，它是winforms，我想要数据绑定而不是一大堆手动更新控件。我不想通过添加更多的分离来增加更多的复杂性，因为这里没有足够的好处。这足以证明这一点:)。

我希望它有助于其他VB程序员。

基类：

Imports System.ComponentModel
Imports System.Runtime.CompilerServices

Public MustInherit Class BaseModel
    Implements INotifyPropertyChanged
    Protected Function SetProperty(Of T)(ByRef storage As T, value As T, <CallerMemberName> Optional propertyName As String = Nothing) As Boolean
        If Equals(storage, value) Then Return False
        storage = value
        OnPropertyChanged(propertyName)
        Return True
    End Function

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Protected Overridable Sub OnPropertyChanged(propertyName As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub
End Class

公共字符串属性在VB TT文件中不存在（确保它的ModelName.tt不是ModelName.Context.tt）。注意使用条件为可空的比较。如果你没有这个，你就不会被解雇！

Public Function AnyProperty(accessibility As String, type As String, name As String, getterAccessibility As String, setterAccessibility As String, defaultValue As String)
            Dim CompareLine = if(type.contains("Null"), $"if Not Nullable.Equals({name}, value) ", $"if {name} <> value ")
            Return String.Format( _
                CultureInfo.InvariantCulture, _
                "{6}    Private _{0} As {1}{2}{6}" & _
                "    {3} Property {0} As {1}{6}" & _
                "        {4}Get{6}" & _
                "            Return _{0}{6}" & _
                "        End Get{6}" & _
                "        {5}Set(ByVal value As {1}){6}" & _
                "             {7} then  SetProperty(_{0}, value){6}" & _
                "        End Set{6}" & _
                "    End Property",  _
                name, _
                type, _
                defaultValue, _
                accessibility, _
                getterAccessibility, _
                setterAccessibility, _
                Environment.NewLine,
                CompareLine)
 End Function

<强> EntityClassOpening

Public Function EntityClassOpening(entity As EntityType) As String
        Return String.Format( _
            CultureInfo.InvariantCulture, _
            "Partial {0} {1}Class {2}{3}", _
            Accessibility.ForType(entity), _
            _code.SpaceAfter(_code.MustInheritOption(entity)), _
            _code.Escape(entity), _
            _code.StringBefore(Environment.Newline & " Inherits ", If(String.IsNullOrEmpty(_typeMapper.GetTypeName(entity.BaseType)), "BaseModel", _typeMapper.GetTypeName(entity.BaseType))))
  End Function

如果我发现任何有意义的内容，我会这样做。

请注意我的用例：轻量级VB项目，没有理由介绍MVVM / MVC和存储库层，但有充分的理由想要数据绑定而不是烦人的控件条件更新 - 其中许多都有一个EditValue属于类型Object（Devexpress winforms控件）。

Answer 8

如果在直接绑定到数据模型类时需要属性更改通知，则应继续使用ObjectContext。

轻量级DBContext类适用于MVVM或MVVMC等模式，其中视图模型实现属性更改通知，而UI仅绑定到视图模型的属性。您永远不会在这些模式中绑定到数据模型类。