这可能是一个非常初学的问题,但我已经搜索了很多主题并且无法找到相同的情况,尽管我确信这种情况一直都在发生.
我的项目/计划将跟踪建筑项目图纸的变化,并在更改图纸时向人们发送通知.
将有许多建筑项目(工地),每个建筑项目中都会有很多图纸.每个图纸都会有一些修改(当它们被更改时,会创建一个新版本).
这是我的项目类
public class Project
{
private readonly List<Drawing> _drawings = new List<Drawing>(30);
private readonly List<Person> _autoRecepients = new List<Person>(30);
public int ID { get; private set; }
public string ProjectNumber { get; private set; }
public string Name { get; private set; }
public bool Archived { get; private set; }
public List<Person> AutoRecepients { get { return _autoRecepients; } }
public Project(int id,string projectNumber,string name)
{
if (id < 1) { id = -1; }
ID = id;
ProjectNumber = projectNumber;
Name = name;
}
public bool AddDrawing(Drawing drawing)
{
if (drawing == null) return false;
if (_drawings.Contains(drawing)) { return true; }
_drawings.Add(drawing);
return _drawings.Contains(drawing);
}
public void Archive()
{
Archived = true;
}
public bool DeleteDrawing(Drawing drawing)
{
return _drawings.Remove(drawing);
}
public IEnumerable<Drawing> ListDrawings()
{
return _drawings.AsReadOnly();
}
public override string ToString()
{
return string.Format("{0} {1}",ProjectNumber,Name);
}
}
这是我的绘画课
public class Drawing : IDrawing
{
private List<IRevision> _revisions = new List<IRevision>(5);
private List<IssueRecord> _issueRecords = new List<IssueRecord>(30);
private IRevision _currentRevision;
public int ID { get; private set; }
public string Name { get; private set; }
public string Description { get; set; }
public Project Project { get; private set; }
public IRevision CurrentRevision { get { return _currentRevision; } }
public Drawing(int id,string name,string description,Project project)
{
// To be implemented
}
/// <summary>
/// Automatically issue the current revision to all Auto Recepients
/// </summary>
public void AutoIssue(DateTime date)
{
AutoIssue(date,_currentRevision);
}
/// <summary>
/// Automatically issue a particular revision to all Auto Recepients
/// </summary>
public void AutoIssue(DateTime date,IRevision revision)
{
}
public void IssueTo(Person person,DateTime date,IRevision revision)
{
_issueRecords.Add(new IssueRecord(date,this,revision,person));
throw new NotImplementedException();
}
public void IssueTo(Person person,DateTime date)
{
IssueTo(person,date,_currentRevision);
}
public void IssueTo(IEnumerable<Person> people,DateTime date)
{
IssueTo(people,_currentRevision);
}
public void IssueTo(IEnumerable<Person> people,IRevision revision)
{
foreach (var person in people)
{
IssueTo(person,revision);
}
}
public void Rename(string name)
{
if (string.IsNullOrWhiteSpace(name)) { return; }
Name = name;
}
public void Revise(IRevision revision)
{
if (revision.Name == null ) return;
_revisions.Add(revision);
_currentRevision = revision;
}
public struct IssueRecord
{
public int ID { get; private set; }
public DateTime Date { get; private set; }
public IDrawing Drawing { get; private set; }
public IRevision Revision { get; private set; }
public Person Person { get; private set; }
public IssueRecord(int id,IDrawing drawing,IRevision revision,Person person)
{
if (id < 1) { id = -1; }
ID = id;
Date = date;
Drawing = drawing;
Revision = revision;
Person = person;
}
}
}
这是Revision结构
public struct Revision : IRevision
{
public int ID { get; private set; }
public string Name { get; }
public DateTime Date { get; set; }
public IDrawing Drawing { get; }
public IDrawingFile DrawingFile { get; private set; }
public Revision(int id,IDrawingFile drawingFile)
{
if (name == null) { throw new ArgumentNullException("name","Cannot create a revision with a null name"); }
if (drawing == null) { throw new ArgumentNullException("drawing","Cannot create a revision with a null drawing"); }
if (id < 1) { id = -1; }
ID = id;
Name = name;
Drawing = drawing;
Date = date;
DrawingFile = drawingFile;
}
public Revision(string name,IDrawingFile drawingFile)
: this(-1,name,drawing,drawingFile)
{
}
public Revision(string name,IDrawing drawing)
: this(-1,DateTime.Today,null)
{
}
public void ChangeID(int id)
{
if (id < 1) { id = -1; }
ID = id;
}
public void SetDrawingFile(IDrawingFile drawingFile)
{
DrawingFile = drawingFile;
}
}
我的问题是在绘图类中的项目引用和修订结构中的绘图引用.
好像有点代码味道？
它似乎也可能导致将来序列化问题.
有一个更好的方法吗？
绘图对象似乎有必要知道它属于哪个项目,这样如果我正在使用单个绘图对象,我就可以知道它们属于哪个项目.
类似地,每个修订版本基本上由图纸“拥有”或者是图纸的一部分.没有绘图,修订没有意义,所以它需要引用它所属的绘图？
任何建议将不胜感激.
解决方法
你所拥有的不仅仅是循环引用,而是两个例子
可以从两端导航的亲子关系.
是的,这是正常的,可接受的,不是代码味道.是的,一些序列化工具需要您提示.例如Newtonsoft.Json需要ReferenceLoopHandling.Ignore设置.
作为一个概念的导航性并不总是在OO设计中被讨论,这是不幸的,因为它只是你想要的概念. (这是UML中的明确术语).
您通常不需要从两端进行导航.父子关系通常仅从父对子编码.这很常见.例如,invoiceline类很少需要其父发票的显式字段,因为大多数应用程序仅在检索父发票后查看该行.
所以设计决定不是,
“没有绘画,修改是否有意义？”
但
“我是否需要找到仅给出修订版的图纸？”
我的猜测是你的修订就像发票行,而不需要导航到他们的父母.图纸的答案< - >项目对我来说并不明显. (这是关于您的域名的分析问题,而不是代码式问题).
这是OO代码与sql之间的显着差异.在sql数据库中,它必须是包含对其父图形ID的引用的修订表.在OO代码中,父类几乎总是拥有对子代的引用.孩子们通常不需要引用他们的父母,因为你访问孩子的唯一方法是已经拥有父母.
