c# - 如何删除 DataContractSerializer 冗长

Question

我们正在尝试序列化一个对象树。虽然我们已经成功了。我希望找到一种方法来简化生成的 xml。

对象看起来像下面这样:

public class RuleSet<T>
{
    public IEnumerable<IState<T>> States { get; set; }
    public IEnumerable<ICondition<T>> Conditions { get; set; }
}

public class State<T> : IState<T>
{
    public string Id { get; set; }
    public List<ITransition<T>> Transitions { get; set; }
}

public class Transition<T> : ITransition<T>
{
    public ICondition<T> Condition { get; set; }
    public IState<T> Next { get; set; }
}

public class Condition<T> : ICondition<T>
{
    public string Id { get; set; }
    public string Name { get; set; }    
}

目前我们正在使用一个非常简单的序列化代码:

public void blah()
{
    var condition1 = new Condition<object>() {
        Id = "C1", AttributeName = "Foo", ExpectedValue = "Bar"
    };
    var condition2 = new Condition<object>() {
        Id = "C2", AttributeName = "Bar", ExpectedValue = "Foo"
    };

    var state1Transitions = new List<ITransition<object>>();
    var state2Transitions = new List<ITransition<object>>();
    var state3Transitions = new List<ITransition<object>>();

    var state = new State<object> {
        Id = "S1", Transitions = state1Transitions
    };
    var state2 = new State<object> {
        Id = "S2", Transitions = state2Transitions
    };
    var state3 = new State<object> {
        Id = "S3", Transitions = state3Transitions
    };

    state1Transitions.Add(new Transition<object> {
        Condition = condition1, Next = state2
    });
    state1Transitions.Add(new Transition<object> {
        Condition = condition2, Next = state3
    });
    state2Transitions.Add(new Transition<object> {
        Condition = condition2, Next = state3
    });
    var ruleSet = new RuleSet<object> {
        States = new List<IState<object>> {state, state2, state3}, 
        Conditions = new List<ICondition<object>>{condition1, condition2}
    };

    var stream1 = new MemoryStream();

    var serializer = new DataContractSerializer(typeof(RuleSet<object>),
        new List<Type> { 
            typeof(State<object>), 
            typeof(Transition<object>),
        typeof(AttributeEqualTo<object>)
    });

    serializer.WriteObject(stream1, ruleSet);
    stream1.Position = 0;

    var xml = new StreamReader(stream1).ReadToEnd();
    Console.WriteLine(xml);
}

当生成 XML 时，每个级别的输出都是完整的，而不是仅包含对对象的引用。基本上每个Transition<T>我们得到每个状态和条件的完整对象定义，即使它们是在别处定义的。

有没有办法让这些只是引用？

Answer 1

这一切都取决于您如何创建 DataContractSerializer .

您需要调用 the overload of the constructor that allows you to indicate that you will preserve object references ，具有以下签名:

public DataContractSerializer(
    Type type,
    IEnumerable<Type> knownTypes,
    int maxItemsInObjectGraph,
    bool ignoreExtensionDataObject,
    bool preserveObjectReferences,
    IDataContractSurrogate dataContractSurrogate
)

您可以为大多数参数传递默认值。在您的情况下，对 DataContractSerializer 构造函数的调用将如下所示:

var serializer = new DataContractSerializer(typeof(RuleSet<object>),
    new [] {
        typeof(State<object>),
        typeof(Transition<object>),
        typeof(AttributeEqualTo<object>)
    },
    Int32.MaxValue,
    false,
    /* This is the important flag to set. */
    true,
    null
);

请注意，从 preserveObjectReferences 参数文档中，它使用非标准 XML(强调我的):

preserveObjectReferences

Type: System.Boolean

true to use non-standard XML constructs to preserve object reference data; otherwise, false.

如果您需要 .NET 之外的其他代码来解释它，那么理清这些引用可能会很困难(但不应该是不可能的)。

但是，它会阻止对象图 self 复制并减少 XML 的大小(考虑到您的引用的深度，可能会大大减少)。