Table<T>.Attach()方法的工作方式之后，我有另一个问题。DataContext的状态跟踪机制中分离？基本上，我想拉出一条记录并更改记录上的数据。但是，当我在同一个DataContext实例上调用SubmitChanges()时，除非我已经显式地调用Attach()，否则我不希望记录被更新。如何实现这一点？如果你要使用LINQ to SQL，我强烈建议你改变设计以适应LINQ to SQL提交所有已修改实体的行为。根据我的经验，试图规避此功能只会带来麻烦。
从这个网站了解如何分离linq对象，将此方法添加到要分离的对象中：
public void Detach()
{
GetType().GetMethod("Initialize", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(this, null);
}
/serialization 选项：https://learn.microsoft.com/en-us/dotnet/framework/data/adonet/sql/linq/serialization - Protector one很遗憾，您无法直接将实体从先前的DataContext中分离，除非对实体进行序列化和反序列化。
为了实现您的目的，您可以创建一个从数据库中检索出来的对象的副本并与其一起工作。在这种情况下，原始对象不会受到影响。当更新数据库的时候，您只需将副本附加到您的DataContext即可。
我使用Serialize/Deserialize克隆了从DataContext查询的对象，并将新对象提交到同一个DataContext，没有出现任何问题。如果有任何附加实体，则需要在提交克隆之前使用其ID进行重新查询。
/// <summary>Used for serializing and de-serializing objects.</summary>
public static class Serializer
{
/// <summary>Clones an object.</summary>
/// <typeparam name="T">The type of object to be cloned.</typeparam>
/// <param name="source">The object to be cloned.</param>
/// <returns>A clone of the specified object.</returns>
public static T Clone<T>(T source)
{
return Deserialize<T>(Serialize(source));
}
/// <summary>Serializes an object as an XML string.</summary>
/// <param name="value">A System.Object representing the object to be serialized.</param>
/// <returns>A System.String representing an XML representation of the specified object.</returns>
public static string Serialize(object value)
{
if (value.GetType() == typeof(string))
{
return value.ToString();
}
StringWriter stringWriter = new StringWriter();
using (XmlWriter writer = XmlWriter.Create(stringWriter))
{
DataContractSerializer serializer = new DataContractSerializer(value.GetType());
serializer.WriteObject(writer, value);
}
return stringWriter.ToString();
}
/// <summary>Creates an object from an XML representation of the object.</summary>
/// <typeparam name="T">The type of object to be created.</typeparam>
/// <param name="serializedValue">A System.String representing an XML representation of an object.</param>
/// <returns>A new object.</returns>
public static T Deserialize<T>(string serializedValue)
{
Type type = typeof(T);
using (StringReader stringReader = new StringReader(serializedValue))
{
using (XmlReader reader = XmlReader.Create(stringReader))
{
DataContractSerializer serializer = new DataContractSerializer(type);
object deserializedValue = serializer.ReadObject(reader);
return (T)deserializedValue;
}
}
}
}
DuplicateKeyException 异常，并且错误信息为 不能添加已经在使用中的实体键。。 - Kirk Broadhurst return JsonConvert.SerializeObject(oModel, new JsonSerializerSettings() { ContractResolver = new DNSConfigurationModel.DNSConfigSerializer() });
/// <summary>
/// Helper class to ensure that we do not serialize the domainAdvancedDNS child objects
/// (we will create our own child collections for serialization). We also suppress serialization of the key ID's.
/// </summary>
public class DNSConfigSerializer : DefaultContractResolver
{
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
IList<JsonProperty> properties = base.CreateProperties(type, memberSerialization);
return (from p in properties
where p.PropertyName != "DomainAdvancedDNS" &&
p.PropertyName != "domainAdvancedDNSSRVs" &&
!(p.DeclaringType.Name == "DomainAdvancedDN" && p.PropertyName == "domainAdvancedDNSConfigID") &&
p.PropertyName != "DomainAdvancedDNSID" &&
p.PropertyName != "domainAdvancedDNSSRVID"
select p).ToList();
}
}