Question

我正在寻找一个简单的Xml存储库（GetAll，Add，Update，Delete）示例。

每个人都说“使用存储库模式是一个好主意，因为你可以交换你的数据存储位置......”现在我需要将我的数据存储在xml文件中，并且不知道如何实现XML存储库。我在谷歌搜索过，找不到它。

如果可能，发送包含关系数据句柄的示例。就像在EF上保存产品实体一样，所有依赖于产品的实体也都是持久的。

Answer 1

好吧，Petter解决方案很好。

为了分享我的实施，我将再次回答我的问题，我希望这对某人有用。请评价和评论。

public interface IRepository<T>
{
    IEnumerable<T> GetAll();
    IEnumerable<T> GetAll(object parentId);
    T GetByKey(object keyValue);

    void Insert(T entidade, bool autoPersist = true);
    void Update(T entidade, bool autoPersist = true);
    void Delete(T entidade, bool autoPersist = true);

    void Save();
}

XML存储库的基类

public abstract class XmlRepositoryBase<T> : IRepository<T>
{

    public virtual XElement ParentElement { get; protected set; }

    protected XName ElementName { get; private set; }

    protected abstract Func<XElement, T> Selector { get; }

    #endregion

    protected XmlRepositoryBase(XName elementName)
    {
        ElementName = elementName;

        // clears the "cached" ParentElement to allow hot file changes
        XDocumentProvider.Default.CurrentDocumentChanged += (sender, eventArgs) => ParentElement = null;
    }

    #region

    protected abstract void SetXElementValue(T model, XElement element);

    protected abstract XElement CreateXElement(T model);

    protected abstract object GetEntityId(T entidade);

    #region IRepository<T>

    public T GetByKey(object keyValue)
    {
        // I intend to remove this magic string "Id"
        return XDocumentProvider.Default.GetDocument().Descendants(ElementName)
            .Where(e => e.Attribute("Id").Value == keyValue.ToString())
            .Select(Selector)
            .FirstOrDefault();
    }

    public IEnumerable<T> GetAll()
    {
        return ParentElement.Elements(ElementName).Select(Selector);
    }

    public virtual IEnumerable<T> GetAll(object parentId)
    {
        throw new InvalidOperationException("This entity doesn't contains a parent.");
    }

    public virtual void Insert(T entity, bool autoPersist = true)
    {
        ParentElement.Add(CreateXElement(entity));

        if (autoPersist)
            Save();
    }

    public virtual void Update(T entity, bool autoPersist= true)
    {
        // I intend to remove this magic string "Id"
        SetXElementValue(
            entity,
            ParentElement.Elements().FirstOrDefault(a => a.Attribute("Id").Value == GetEntityId(entity).ToString()
        ));

        if (persistir)
            Save();
    }

    public virtual void Delete(T entity, bool autoPersist = true)
    {
        ParentElement.Elements().FirstOrDefault(a => a.Attribute("Id").Value == GetEntityId(entity).ToString()).Remove();

        if (autoPersist)
            Save();
    }


    public virtual void Save()
    {
        XDocumentProvider.Default.Save();
    }
    #endregion

    #endregion
}

还有2个抽象类，一个是独立实体，另一个是子实体。为了避免每次都读取Xml文件，我做了一种缓存控制

public abstract class EntityXmlRepository<T> : XmlRepositoryBase<T>
{
    #region cache control

    private XElement _parentElement;
    private XName xName;

    protected EntityXmlRepository(XName entityName)
        : base(entityName)
    {
    }

    public override XElement ParentElement
    {
        get
        {
            // returns in memory element or get it from file
            return _parentElement ?? ( _parentElement = GetParentElement() );
        }
        protected set
        {
            _parentElement = value;
        }
    }

    /// <summary>
    /// Gets the parent element for this node type
    /// </summary>
    protected abstract XElement GetParentElement();
    #endregion
}

现在实现子类型

public abstract class ChildEntityXmlRepository<T> : XmlRepositoryBase<T>
{
    private object _currentParentId;
    private object _lastParentId;

    private XElement _parentElement;

    public override XElement ParentElement
    {
        get 
        {
            if (_parentElement == null)
            {
                _parentElement = GetParentElement(_currentParentId);
                _lastParentId = _currentParentId;
            }
            return _parentElement;
        }
        protected set 
        {
            _parentElement = value; 
        }
    }

    /// <summary>
    /// Defines wich parent entity is active
    /// when this property changes, the parent element field is nuled, forcing the parent element to be updated
    /// </summary>
    protected object CurrentParentId
    {
        get
        {
            return _currentParentId;
        }
        set
        {
            _currentParentId = value;
            if (value != _lastParentId)
            {
                _parentElement = null;
            }
        }
    }       



    protected ChildEntityXmlRepository(XName entityName) : base(entityName){}

    protected abstract XElement GetParentElement(object parentId);

    protected abstract object GetParentId(T entity);


    public override IEnumerable<T> GetAll(object parentId)
    {
        CurrentParentId = parentId;
        return ParentElement.Elements(ElementName).Select(Selector);
    }

    public override void Insert(T entity, bool persistir = true)
    {
        CurrentParentId = GetParentId(entity);
        base.Insert(entity, persistir);
    }

    public override void Update(T entity, bool persistir = true)
    {
        CurrentParentId = GetParentId(entity);
        base.Update(entity, persistir);
    }

    public override void Delete(T entity, bool persistir = true)
    {
        CurrentParentId = GetParentId(entity);
        base.Delete(entity, persistir);
    }
}

现在，实际的实施

public class RepositorioAgendamento : EntityXmlRepository<Agendamento>, IRepositorioAgendamento
{
    protected override Func<XElement, Agendamento> Selector
    {
        get
        {
            return x => new Agendamento() {
                Id = x.Attribute("Id").GetGuid(),
                   Descricao = x.Attribute("Descricao").Value,
                   TipoAgendamento = x.Attribute("TipoAgendamento").GetByte(),
                   Dias = x.Attribute("Dias").GetByte(),
                   Data = x.Attribute("Data").GetDateTime(),
                   Ativo = x.Attribute("Ativo").GetBoolean(),
            };
        }
    }

    protected override XElement CreateXElement(Agendamento agendamento)
    {
        agendamento.Id = Guid.NewGuid();

        return new XElement(ElementName,
                new XAttribute("Id", agendamento.Id),
                new XAttribute("Descricao", agendamento.Descricao),
                new XAttribute("TipoAgendamento", agendamento.TipoAgendamento),
                new XAttribute("Dias", agendamento.Dias),
                new XAttribute("Data", agendamento.Data),
                new XAttribute("Ativo", agendamento.Ativo),
                new XElement(XmlNames.GruposBackup),
                new XElement(XmlNames.Credenciais)
                );
    }

    protected override void SetXElementValue(Agendamento modelo, XElement elemento)
    {
        elemento.Attribute("Descricao").SetValue(modelo.Descricao);
        elemento.Attribute("TipoAgendamento").SetValue(modelo.TipoAgendamento);
        elemento.Attribute("Dias").SetValue(modelo.Dias);
        elemento.Attribute("Data").SetValue(modelo.Data);
        elemento.Attribute("Ativo").SetValue(modelo.Ativo);
    }


    public RepositorioAgendamento() : base(XmlNames.Agendamento)
    {

    }

    protected override XElement GetParentElement()
    {
        return XDocumentProvider.Default.GetDocument().Elements(XmlNames.Agendamentos).First();
    }

    protected override object GetEntityId(Agendamento entidade)
    {
        return entidade.Id;
    }

    public IEnumerable<Agendamento> ObterAtivos()
    {
        return ParentElement.Elements()
            .Where(e => e.Attribute("Ativo").GetBoolean())
            .Select(Selector);
    }
}

现在，XDocumentProvider。它的功能是抽象对xml文件的访问，并统一到所有存储库，XDocument是数据上下文。 这可以命名为UnitOfWork ？

public abstract class XDocumentProvider
{
    // not thread safe yet
    private static bool pendingChanges;

    private bool _documentLoadedFromFile;

    FileSystemWatcher fileWatcher;

    public static XDocumentProvider Default;

    public event EventHandler CurrentDocumentChanged;

    private XDocument _loadedDocument;

    public string FileName { get; set; }


    protected XDocumentProvider()
    {
        fileWatcher = new FileSystemWatcher();
        fileWatcher.NotifyFilter = NotifyFilters.LastWrite;
        fileWatcher.Changed += fileWatcher_Changed;
    }

    void fileWatcher_Changed(object sender, FileSystemEventArgs e)
    {
        if (_documentLoadedFromFile && !pendingChanges)
        {
            GetDocument(true);
        }
    }


    /// <summary>
    /// Returns an open XDocument or create a new document
    /// </summary>
    /// <returns></returns>
    public XDocument GetDocument(bool refresh = false)
    {
        if (refresh || _loadedDocument == null)
        {
            // we need to refactor it, but just to demonstrate how should work I will send this way ;P
            if (File.Exists(FileName))
            {
                _loadedDocument = XDocument.Load(FileName);
                _documentLoadedFromFile = true;

                if (fileWatcher.Path != Environment.CurrentDirectory)
                {
                    fileWatcher.Path = Environment.CurrentDirectory;
                    fileWatcher.Filter = FileName;
                    fileWatcher.EnableRaisingEvents = true;
                }
            }
            else
            {
                _loadedDocument = CreateNewDocument();
                fileWatcher.EnableRaisingEvents = false;
                _documentLoadedFromFile = false;
            }

            if(CurrentDocumentChanged != null) CurrentDocumentChanged(this, EventArgs.Empty);
        }

        return _loadedDocument;
    }

    /// <summary>
    /// Creates a new XDocument with a determined schemma.
    /// </summary>
    public abstract XDocument CreateNewDocument();

    public void Save()
    {
        if (_loadedDocument == null)
            throw new InvalidOperationException();

        try
        {
            // tells the file watcher that he cannot raise the changed event, because his function is to capture external changes.
            pendingChanges = true;
            _loadedDocument.Save(FileName);
        }
        finally
        {
            pendingChanges = false;
        }
    }
}

然后，我可以为不同的实体提供许多存储库，在单个数据上下文中添加挂起持久性操作。

我已经对我的应用程序进行了测试，该应用程序使用这个存储库使用模拟并运行良好。

在我的IoC配置中，我必须为XDocumentProvider设置Default。如有必要，我们可以通过构造函数而不是静态“默认”属性传递XDocumentProvider

您如何看待我的实施？

由于

Answer 2

一位同事和我实现了这样一个XML存储库，它被称为XmlRepository： - ）。

它内部使用linq to XML构建，外部访问类似于使用linq进行nhibernate的方式。它通过linq to objects完成，客户端代码中的用法非常简单，易于理解，因为XML注释界面简单易懂。

当前版本（程序集）没有为子类或1：n关系内置支持，但是您可以在上面的站点上找到的当前开发源代码都内置了它们。

它还没有完全准备好发布 - 它可能有一些小错误，但尝试一下，如果你愿意，可以采取源代码并改进它。它是开源的。

对开源（阅读：唯一来源）项目的任何评论，愿望，建设性批评和补丁将使我的同事（Golo Roden）和我高兴并将项目带到更好的状态。

示例应用程序可用here（文本为德语）。

Xml存储库实现

2 个答案: