要从一个类访问属性到另一个类 [英] Ow to access property from one class to another class
问题描述
命名空间Samba.Modules.MenuModule
{
[导出，PartCreationPolicy（CreationPolicy.NonShared）]
公共类MenuItemViewModel：EntityViewModelBase， IEntityCreator
{
私人只读IMenuService _menuService;
[ImportingConstructor]
public MenuItemViewModel（IMenuService menuService）
{
AddPortionCommand = new CaptionCommand（string.Format（Resources.Add_f，Resources.Portion），OnAddPortion）;
DeletePortionCommand = new CaptionCommand（string.Format（Resources.Delete_f，Resources.Portion），OnDeletePortion，CanDeletePortion）;
_menuService = menuService;
}
公共字符串条形码
{
get {return Model.Barcode ?? ; }
set {Model.Barcode = value; }
}
====>我必须把这个条形码发给我的班级。
我的班级是
名称空间Samba.Presentation.Common.ModelBase
{
公共抽象类EntityViewModelBase：VisibleViewModelBase，其中TModel：class，IEntityClass
{
private bool _modelSaved;
private IValidator _validator;
protected EntityViewModelBase（）
{
SaveCommand = new CaptionCommand（Resources .Save，OnSave，CanSave）;
}
[可浏览（假）]
公共TModel模型{get;组; }
[可浏览（假）]
public ICaptionCommand SaveCommand {get;私人集; }
protected virtual void OnSave（字符串值）
{
if（CanSave（））
{
string barcode =192.0.0.1;
//检查IP是否重复
string constring = LocalSettings.ConnectionString +;初始目录= sTMS 3;;
SqlConnection con = new SqlConnection（）;
con.ConnectionString = constring;
SqlCommand check_Item = new SqlCommand（SELECT COUNT（*）FROM MenuItems WHERE（Barcode ='+ barcode +'），con）;
con.Open（）;
int UserExist =（int）check_Item.ExecuteScalar（）;
if（UserExist> 0）
{
MessageBox.Show（IP已经exsit.Please再试一次，Resources.CantSave）;
ErrorMessage = ;
}
其他
{
_modelSaved = true;
if（ Model.Id == 0）
{
this.PublishEvent（EventTopicNames.AddedModelSaved）;
}
this.PublishEvent（EventTopicNames.ModelAddedOrDeleted）;
（（VisibleViewModelBase）this）.PublishEvent（EventTopicNames.ViewClosed）;
}
con。关闭（）;
}
我尝试过： < br $>
i已经尝试了很多解决方案n =但是因为这是非共享类卡住了
namespace Samba.Modules.MenuModule
{
[Export, PartCreationPolicy(CreationPolicy.NonShared)]
public class MenuItemViewModel : EntityViewModelBase, IEntityCreator
{
private readonly IMenuService _menuService;
[ImportingConstructor]
public MenuItemViewModel(IMenuService menuService)
{
AddPortionCommand = new CaptionCommand(string.Format(Resources.Add_f, Resources.Portion), OnAddPortion);
DeletePortionCommand = new CaptionCommand(string.Format(Resources.Delete_f, Resources.Portion), OnDeletePortion, CanDeletePortion);
_menuService = menuService;
}
public string Barcode
{
get { return Model.Barcode ?? ""; }
set { Model.Barcode = value; }
}
====> i have to access this barcode to my class.
my class is
namespace Samba.Presentation.Common.ModelBase
{
public abstract class EntityViewModelBase : VisibleViewModelBase where TModel : class, IEntityClass
{
private bool _modelSaved;
private IValidator _validator;
protected EntityViewModelBase()
{
SaveCommand = new CaptionCommand(Resources.Save, OnSave, CanSave);
}
[Browsable(false)]
public TModel Model { get; set; }
[Browsable(false)]
public ICaptionCommand SaveCommand { get; private set; }
protected virtual void OnSave(string value)
{
if (CanSave())
{
string barcode = "192.0.0.1";
//check if IP is duplicate or not
string constring = LocalSettings.ConnectionString + ";Initial Catalog=sTMS 3;";
SqlConnection con = new SqlConnection();
con.ConnectionString = constring;
SqlCommand check_Item = new SqlCommand("SELECT COUNT(*) FROM MenuItems WHERE (Barcode ='" + barcode + "')", con);
con.Open();
int UserExist = (int)check_Item.ExecuteScalar();
if (UserExist > 0)
{
MessageBox.Show("IP already exsit.Please try again", Resources.CantSave);
ErrorMessage = "";
}
else
{
_modelSaved = true;
if (Model.Id == 0)
{
this.PublishEvent(EventTopicNames.AddedModelSaved);
}
this.PublishEvent(EventTopicNames.ModelAddedOrDeleted);
((VisibleViewModelBase)this).PublishEvent(EventTopicNames.ViewClosed);
}
con.Close();
}
What I have tried:
i have tried many solution n=but because this is non shared class m stuck
推荐答案
因为你的条形码属性是非静态的，您需要一个MenuModule类的实例才能获取值 - 就像每个实例一样不同的价值。您使用new关键字创建实例。
实例就像汽车 - 你可以拥有一辆汽车所有四轮车都是Car实例。在现实世界中你已经知道这一点：这辆车与那辆车不同; 我的车与你的车颜色不同。每辆车都是汽车类别的独立实例，独立于所有其他汽车创建，购买，销售和驾驶。
计算机中的类别相同：您可以拥有MenuModule类的多个实例，每个实例都有一个单独的Barcode属性值。因此，您需要准确指定您要引用的类的哪个实例，全部是：
Because your Barcode property is non-static, you need an instance of the MenuModule class in order to get the value - as each instance will have a different value. You create an instance using thenewkeyword.
An instance is like a Car - you can have a Car class, and all four-wheeled vehicles are Car instances. In the real world you already know this: "this car" is a different vehicle to "that car"; "my car" is a different colour to "your car". Each car is a separate instance of the class of Cars, and is created, bought, sold, and driven independently of all the others.
Classes in computers are the same: you can have multiple instances of your MenuModule class, and each will have a separate Barcode property value. So you need to specify exactly which instance of the class you are trying to refer to, is all:
MenuModule mm = new MenuModule();
...
Console.WriteLine(mm.Barcode);
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