Question

我正在尝试使用计算列来显示在我的网格中。

我有一个由EF代码生成器自动生成的具有三个属性的部分类：我正在尝试创建另一个部分类并在那里添加计算字段，例如

Public partial class Employee
{
public decimal? totalSalary
{
get

{
return salary*wagerate+bonus;
}
}
}

它首次正常工作，但在工资/奖金/小时数改变时不起作用。我在网格中使用这些字段

这是我的代码由EF实体生成器生成

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated from a template.
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Globalization;
using System.Runtime.Serialization;
using System.ComponentModel.DataAnnotations;

namespace Employees.Contract
{
[DataContract(IsReference = true)]
[KnownType(typeof(Department))]
[KnownType(typeof(PropertyType))]
public partial class Employee: IObjectWithChangeTracker, INotifyPropertyChanged,IDataErrorInfo
{

    [NonSerialized]
    private CLOS.Contract.Validation.DataErrorInfoSupport dataErrorInfoSupport;

    public Employee()
    {            
        dataErrorInfoSupport = new CLOS.Contract.Validation.DataErrorInfoSupport(this);
        Init();
    }

    partial void Init();

    string IDataErrorInfo.Error { get { return dataErrorInfoSupport.Error; } }

    string IDataErrorInfo.this[string memberName] { get { return dataErrorInfoSupport[memberName]; } }

    #region Primitive Properties


    [DataMember]
    public Nullable<decimal> Salary
    {
        get { return _salary; }
        set
        {
            if (_salary != value)
            {
                _salary = value;
                OnPropertyChanged("Salary");
            }
        }
    }
    private Nullable<decimal> _salary;

    [DataMember]
    public Nullable<decimal> WageRate
    {
        get { return _wageRate; }
        set
        {
            if (_wageRate != value)
            {
                _wageRate = value;
                OnPropertyChanged("WageRate");
            }
        }
    }
    private Nullable<decimal> _wageRate;

    [DataMember]
    public Nullable<decimal> Bonus
    {
        get { return _bonus; }
        set
        {
            if (_bonus != value)
            {
                _bonus = value;
                OnPropertyChanged("Bonus");
            }
        }
    }
    private Nullable<decimal> _bonus;

    #endregion
    #region Navigation Properties

    [DataMember]
    public Department Department
    {
        get { return _department; }
        set
        {
            if (!ReferenceEquals(_department, value))
            {
                var previousValue = _department;
                _department = value;
                OnNavigationPropertyChanged("Department");
            }
        }
    }
    private Borrower _department;

    [DataMember]
    public PropertyType PropertyType
    {
        get { return _propertyType; }
        set
        {
            if (!ReferenceEquals(_propertyType, value))
            {
                var previousValue = _propertyType;
                _propertyType = value;

                OnNavigationPropertyChanged("PropertyType");
            }
        }
    }
    private PropertyType _propertyType;

    #endregion
    #region ChangeTracking

    protected virtual void OnPropertyChanged(String propertyName)
    {
        if (ChangeTracker.State != ObjectState.Added && ChangeTracker.State != ObjectState.Deleted)
        {
            ChangeTracker.State = ObjectState.Modified;
        }
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    protected virtual void OnNavigationPropertyChanged(String propertyName)
    {
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged{ add { _propertyChanged += value; } remove { _propertyChanged -= value; } }
    private event PropertyChangedEventHandler _propertyChanged;
    private ObjectChangeTracker _changeTracker;

    [DataMember]
    public ObjectChangeTracker ChangeTracker
    {
        get
        {
            if (_changeTracker == null)
            {
                _changeTracker = new ObjectChangeTracker();
                _changeTracker.ObjectStateChanging += HandleObjectStateChanging;
            }
            return _changeTracker;
        }
        set
        {
            if(_changeTracker != null)
            {
                _changeTracker.ObjectStateChanging -= HandleObjectStateChanging;
            }
            _changeTracker = value;
            if(_changeTracker != null)
            {
                _changeTracker.ObjectStateChanging += HandleObjectStateChanging;
            }
        }
    }

    private void HandleObjectStateChanging(object sender, ObjectStateChangingEventArgs e)
    {
        if (e.NewState == ObjectState.Deleted)
        {
            ClearNavigationProperties();
        }
    }

    protected bool IsDeserializing { get; private set; }

    [OnDeserializing]
    public void OnDeserializingMethod(StreamingContext context)
    {
        IsDeserializing = true;
    }

    [OnDeserialized]
    public void OnDeserializedMethod(StreamingContext context)
    {
        dataErrorInfoSupport = new CLOS.Contract.Validation.DataErrorInfoSupport(this);
        IsDeserializing = false;
        ChangeTracker.ChangeTrackingEnabled = true;
    }

    protected virtual void ClearNavigationProperties()
    {
        Department = null;
        PropertyType = null;
    }

    #endregion
}

}

如果我将OnPropertyChanged("Salary")放入EF Generated类中的小时，工资，加班属性（这不是一个好主意），这也有效，因为如果该类重新生成，我的代码将被删除

感谢任何帮助。（抱歉格式化，这是我的第一个问题）

由于

Answer 1

在partial类中，使用部分Init方法订阅PropertyChanged事件，并在salary，wagerate或bonus属性更改时通知客户端totalSalary的更改。

这样您就不需要修改生成的代码了。（这就是为什么Init方法是部分的。）

public partial class Employee
{

    partial void Init()
    {
        _propertyChanged += PropertyChangedHandler;
    }

    void PropertyChangedHandler(object sender, PropertyChangedEventArgs args)
    {
        if(args.PropertyName == "salary" ||
           args.PropertyName == "wagerate" ||
           args.PropertyName == "bonus")
         {
             OnPropertyChanged("totalSalary");
         }
    }

    public decimal? totalSalary
    {
        get
        {
            return salary * wagerate + bonus;
        }
    }
}

Answer 2

这就是为什么MVVM是一种流行的设计模式，如果你将Employee（一个Model）包装在一个新类（ViewModel）中，在将它交给网格（View）之前，它将更容易定制。 / p>

然而，让当前代码工作的一种hacky方法是附加到部分类中的当前PropertyChanged事件，如果当前属性名称与其中一个依赖属性匹配，则调用OnPropertyChanged("Salary")（注意递归！）

如何在部分类中创建计算字段 - WPF

2 个答案: