如何使用EF 4.x DbContext生成器获取属性更改通知 [英] How to get property change notifications with EF 4.x DbContext generator
问题描述
使用默认的EF 4代码生成器模板，实体类实现INotifyPropertyChanged，并添加更改和更改属性设置器中的部分方法。
当我使用EF 4.x DbContext生成器时，如下图所示，实体类更轻，而且不包括追踪资产变更的任何方式。
以下是一个示例：
// -------------------------------------------- ----------------------------------
//< auto-generated>
//该代码是从模板生成的。
//
//手动更改此文件可能会导致应用程序出现意外的行为。
//如果重新生成代码，则对该文件的手动更改将被覆盖。
//< / auto-generated>
// -------------------------------------------- ----------------------------------
使用系统;
使用System.Collections.Generic;
命名空间SomeNamespace
{
public partial class SomeTable
{
public SomeTable（）
{
this.Children = new的HashSet<儿童>（）;
}
public long parent_id {get;组; }
public long id {get;组; }
public string filename {get;组; }
public byte [] file_blob {get;组; }
public virtual Parent Parent {get;组; }
public virtual ICollection< Child>孩子{get;组; }
}
}
我一定缺少一个重要的难题，但我的搜索是无效的。所以我的问题是：如何生成类型包括EF 4.3的属性更改通知？
修改
我完全同意@derape答案;但是当EF 4默认代码生成模板已经有钩子时，我很好奇为什么我需要更改 .tt 文件。我的意思是当绑定到WPF DependencyProperty '时呢？没有INotifyPropertyChanged，一个命令对一堆对象中的一组属性所做的更改不会反映在UI中。我缺少什么？
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，快速修补程序，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}局部类{2} {3}：{4}，
Accessibility.ForType（entity），
_code.SpaceAfter（_code.AbstractOption（entity）），
_code.Escape ），
_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）），
设置{_+ _ code.Escape（edmProperty）.ToLower（）+= value; OnPropertyChanged（\+ _ code.Escape（edmProperty）+\）;}，
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
使用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））;
}
进一步向下
foreach（simpleProperties中的var edmProperty）
{
＃>
<＃= codeStringGenerator.Private（edmProperty）＃>
<＃= codeStringGenerator.Property（edmProperty）＃>
<＃
}
foreach（var complexProperty in complexProperties）
{
＃>
<＃= codeStringGenerator.Private（complexProperty）＃>
<＃= codeStringGenerator.Property（complexProperty）＃>
<＃
}
I'm playing around with Entity Framework 4.3, and so I am using the DbContext Generator to create the context and entity classes.
With the default EF 4 code generator template, entity classes implement INotifyPropertyChanged, and also add Changing and Changed partial methods in property setters.
When I use the EF 4.x DbContext generator, as pictured below, the entity classes are much lighter, and do not include any means of tracking property changes.
Here is an example:
//------------------------------------------------------------------------------
// <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; }
}
}
I must be missing an important piece of the puzzle, but my searches have been fruitless. So my question is: how can I have generated types included property change notifications with EF 4.3?
Edit
I fully agree with @derape answer's; but I am curious as to why I would need to change the .tt file when the EF 4 default code generation template already has the hooks. I mean what about when binding to a WPF DependencyProperty'? Without INotifyPropertyChanged, changes done by a command to a bunch of properties in a bunch of objects won't be reflected in the UI. What am I missing?
I recently stumbled upon this problem, i edited my Entity.tt to implement the following changes, a quick patch but works great..
Add the following to the CodeStringGenerator class
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());
}
Add the following to the generator
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));
}
And abit further down
foreach (var edmProperty in simpleProperties)
{
#>
<#=codeStringGenerator.Private(edmProperty)#>
<#=codeStringGenerator.Property(edmProperty)#>
<#
}
foreach(var complexProperty in complexProperties)
{
#>
<#=codeStringGenerator.Private(complexProperty)#>
<#=codeStringGenerator.Property(complexProperty)#>
<#
}
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