在不编写大量样板代码的前提下， [英] Facade a class without writing lots of boilerplate code?

问题描述

假设我有一个来自第三方的课程，这是一个数据模型。它可能有100个属性（一些与公共设置者和吸烟者，其他公共吸烟者，但私人设置者）。我们来调用这个类ContosoEmployeeModel

我想用一个接口（INavigationItem，它有Name和DBID属性）来设计这个类，以允许它在我的应用程序中使用（它是一个PowerShell提供程序，但现在不重要）。但是，它也需要用作ContosoEmployeeModel。

我的初始实现如下所示：

  public class ContosoEmployeeModel 
 {
 //注意这个类不在我的控制之下。我提供了
 //一个我必须使用的实例。 
 
 public DateTime EmployeeDateOfBirth {get;组; } 
 //和其他99个属性。 
} 
 
 public class FacadedEmployeeModel：ContosoEmployeeModel，INavigationItem 
 {
 private ContosoEmployeeModel model; 
 public FacadedEmployeeModel（ContosoEmployeeModel model）
 {
 this.model = model; 
} 
 
 // INavigationItem属性
 string INavigationItem.Name {get; set;} 
 
 int INavigationItem.DBID {get; set;} 
 
 // ContosoEmployeeModel属性
 public DateTime EmployeeDateOfBirth 
 {
 get {return this.model.EmployeeDateOfBirth; } 
 set {this.model.EmployeeDateOfBirth = value; } 
} 
 //现在再写99个属性，如下所示:-( 
} 
  

然而，很明显，这将涉及编写大量的样板代码来公开所有的属性，我宁愿避免这一点，如果可以的话，我可以T4代码生成这个代码一个部分课程，如果没有更好的想法，会做，但我虽然在这里请问有没有人有任何更好的想法使用一些 super wizzy 位于C＃请注意 - 我用于获取ContosoEmployeeModel的API只能返回一个ContosoEmployeeModel - 我无法扩展它以返回FacededEmployeeModel，因此包装模型是只有我能想到的解决方案 - 我是很高兴得到纠正：）

解决方案

另一种方法可能适合您使用AutoMapper将基类映射到这里的门面是示例代码：

  class Program 
 {
 static void Main（string [] args） 
 {
 var model = new Model {Count = 123，Date = DateTime.Now，Name =Some name}; 
 
 Mapper.CreateMap< Model，FacadeForModel>（）; 
 var mappedObject = AutoMapper.Mapper.Map&FacadeForModel>（model）; 
 
 Console.WriteLine（mappedObject）; 
 
 Console.ReadLine（）; 
} 
 
 class模型
 {
 public string Name {get;组; } 
 
 public DateTime Date {get;组; } 
 
 public int Count {get;组; } 
} 
 
接口INavigationItem 
 {
 int Id {get;组; } 
 
 string OtherProp {get;组; } 
} 
 
 class FacadeForModel：Model，INavigationItem 
 {
 public int Id {get;组; } 
 
 public string OtherProp {get;组; } 
} 
} 
  

Let's say I have a class from a 3rd-party, which is a data-model. It has perhaps 100 properties (some with public setters and getters, others with public getters but private setters). Let's call this class ContosoEmployeeModel

I want to facade this class with an interface (INavigationItem, which has Name and DBID properties) to allow it to be used in my application (it's a PowerShell provider, but that's not important right now). However, it also needs to be usable as a ContosoEmployeeModel.

My initial implementation looked like this:

public class ContosoEmployeeModel
{
    // Note this class is not under my control. I'm supplied
    // an instance of it that I have to work with.

    public DateTime EmployeeDateOfBirth { get; set; }
    // and 99 other properties.
}

public class FacadedEmployeeModel : ContosoEmployeeModel, INavigationItem
{
    private ContosoEmployeeModel model;
    public FacadedEmployeeModel(ContosoEmployeeModel model)
    {
        this.model = model;
    }

    // INavigationItem properties
    string INavigationItem.Name { get; set;}

    int INavigationItem.DBID { get; set;}

    // ContosoEmployeeModel properties
    public DateTime EmployeeDateOfBirth
    {
        get { return this.model.EmployeeDateOfBirth; }
        set { this.model.EmployeeDateOfBirth = value; }
    }
    // And now write 99 more properties that look like this :-(
}

However, it's clear that this will involve writing a huge amount of boilerplate code to expose all the properties , and I'd rather avoid this if I can. I can T4 code-generate this code in a partial class, and will do if there aren't any better ideas, but I though I'd ask here to see if anyone had any better ideas using some super wizzy bit of C# magic

Please note - the API I use to obtain the ContosoEmployeeModel can only return a ContosoEmployeeModel - I can't extend it to return a FacededEmployeeModel, so wrapping the model is the only solution I can think of - I'm happy to be corrected though :)

解决方案

The other approach may be suitable for you is to use AutoMapper to map base class to your facade here is sample code:

class Program
    {
        static void Main(string[] args)
        {
            var model = new Model { Count = 123, Date = DateTime.Now, Name = "Some name" };

            Mapper.CreateMap<Model, FacadeForModel>();
            var mappedObject = AutoMapper.Mapper.Map<FacadeForModel>(model);

            Console.WriteLine(mappedObject);

            Console.ReadLine();
        }

        class Model
        {
            public string Name { get; set; }

            public DateTime Date { get; set; }

            public int Count { get; set; }
        }

        interface INavigationItem
        {
            int Id { get; set; }

            string OtherProp { get; set; }
        }

        class FacadeForModel : Model, INavigationItem
        {
            public int Id { get; set; }

            public string OtherProp { get; set; }
        }
    }

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