Question

我有一个表的MSSQL数据库：

CREATE TABLE Hierarchy (
    Id      UNIQUEIDENTIFIER PRIMARY KEY,
    version TIMESTAMP NOT NULL,
    DiscKey INT NOT NULL,
    Enum    INT NOT NULL
);

我有一个基类和两个子类的对象层次结构。我使用属性将对象映射到数据库结构：

enum ObjectType { A = 1, B = 2 }
enum EnumA { Foo = 1, Bar = 2 }
enum EnumB { Xxx = 1, Yyy = 2 }

[Table(Name = "Hierarchy")]
[InheritanceMapping(Code = ObjectType.A, Type = typeof(DerivedA), IsDefault = true)]
[InheritanceMapping(Code = ObjectType.B, Type = typeof(DerivedB))]
class Base
{
    [DataMember, Column(Name = "Id", DbType = "UniqueIdentifier", CanBeNull = false, IsPrimaryKey = true)]
    public Guid Id;

    [Column(Name = "DiscKey", DbType = "int", CanBeNull = false, IsDiscriminator = true)]
    public ObjectType DiscKey;

    [Column(Name = "version", DbType = "RowVersion", CanBeNull = false, IsVersion = true, IsDbGenerated = true)]
    public byte[] Version { get; protected set; }
}

class DerivedA : Base
{
    [DataMember, Column(Name = "Enum", DbType = "int", CanBeNull = false)]
    public EnumA Enum;
}

class DerivedB : Base
{
    [DataMember, Column(Name = "Enum", DbType = "int", CanBeNull = false)]
    public EnumB Enum;
}

注意：我希望将EnumA和EnumB字段存储在一列中！

在两个不同的工作单元中，我正在尝试：创建对象，然后更新它：

var objId = Guid.NewGuid();
var o1 = new DerivedA {Id = objId, Enum = EnumA.Foo};
using (var context = new DataContext(connectionString))
{
    context.GetTable(typeof(Base)).InsertOnSubmit(o1);
    context.SubmitChanges();
}
var o2 = new DerivedA {Id = objId, Enum = EnumA.Bar};
using (var context = new DataContext(connectionString))
{
    context.GetTable(typeof(Base)).Attach(o2, true);
    context.SubmitChanges();
}

问题：第二个SubmitChanges()抛出异常：

Unhandled Exception: System.ArgumentException: The argument 'value' was the wrong type. Expected 'ConsoleApplication8.EnumA'. Actual 'ConsoleApplication8.EnumB'.
at System.Data.Linq.SqlClient.SqlBinder.Visitor.VisitAssign(SqlAssign sa)
at System.Data.Linq.SqlClient.SqlVisitor.Visit(SqlNode node)
at System.Data.Linq.SqlClient.SqlVisitor.VisitUpdate(SqlUpdate update)
at System.Data.Linq.SqlClient.SqlVisitor.Visit(SqlNode node)
at System.Data.Linq.SqlClient.SqlVisitor.VisitBlock(SqlBlock b)
at System.Data.Linq.SqlClient.SqlVisitor.Visit(SqlNode node)
at System.Data.Linq.SqlClient.SqlBinder.Visitor.VisitIncludeScope(SqlIncludeScope scope)
at System.Data.Linq.SqlClient.SqlVisitor.Visit(SqlNode node)
at System.Data.Linq.SqlClient.SqlBinder.Bind(SqlNode node)
at System.Data.Linq.SqlClient.SqlProvider.BuildQuery(ResultShape resultShape, Type resultType, SqlNode node, ReadOnlyCollection`1 parentParameters, SqlNodeAnnotations annotations)
at System.Data.Linq.SqlClient.SqlProvider.BuildQuery(Expression query, SqlNodeAnnotations annotations)
at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query)
at System.Data.Linq.ChangeDirector.StandardChangeDirector.DynamicUpdate(TrackedObject item)
at System.Data.Linq.ChangeDirector.StandardChangeDirector.Update(TrackedObject item)
at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode)
at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode)
at ConsoleApplication8.Program.Main()

但我不会在我的代码中使用DerivedB和EnumB。

Answer 1

从int继承enum。实施例;

枚举EnumA：int {Foo = 1，Bar = 2} 枚举EnumB：int {Xxx = 1，Yyy = 2

Linq to SQL DataContext无法更新数据库中用于继承对象的Enum字段

1 个答案: