Question

也许有人可以提供帮助。

我希望映射Linq-Class不同的数据类型。

这是有效的：

 private System.Nullable<short> _deleted = 1;

 [Column(Storage = "_deleted", Name = "deleted", DbType = "SmallInt", CanBeNull = true)]
    public System.Nullable<short> deleted
    {
        get
        {
            return this._deleted;
        }
        set
        {
            this._deleted = value;
        }
    }

当然可以。但是，当我想为布尔值放置一些逻辑时，不会这样：

 private System.Nullable<short> _deleted = 1;

 [Column(Storage = "_deleted", Name = "deleted", DbType = "SmallInt", CanBeNull = true)]
    public bool deleted
    {
        get
        {
            if (this._deleted == 1)
            {
                return true;
            }
            return false;
        }
        set
        {
    if(value == true)

    {
                this._deleted = (short)1;
    }else
    {   
                this._deleted = (short)0;
    }
        }
    }

我总是遇到运行时错误：

[TypeLoadException: GenericArguments[2], "System.Nullable`1[System.Int16]", on 'System.Data.Linq.Mapping.PropertyAccessor+Accessor`3[T,V,V2]' violates the constraint of type parameter 'V2'.]

我无法将数据库更改为位...我需要在映射类中进行转换。

** 更新

根据mmcteam的说法，使用未映射的方法进行转换就可以了。不太确定是否以这种方式使用OR Mapping，但它有效。

    private System.Nullable<short> _deleted = 1;

    public bool deleted
    {
        get
        {
            if (this._deleted == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
        set
        {
            if (value)
            {
                this._deleted = 1;
            }
            else
            {
                this._deleted = 0;
            }
        }
    }


    [Column(Storage = "_deleted", Name = "deleted", DbType = "SmallInt", CanBeNull = true)]
    private short? deleted_smallint
    {
        get
        {
            return this._deleted;
        }
        set
        {
            this._deleted = value;
        }
    }

** 通知/问题

您不能在linq查询中使用未映射的方法！

                 var result = from p in dc.Products
                               where p.enabled && !p.deleted 
                select p;

导致不支持sql异常。如果没有where条件，数据将以正确的值显示出来。

Answer 1

或者只是在您的行类中再添加一个属性，然后将前一个属性转换为bool。

Answer 2

你不想要这个：

[Column(Storage = "_deleted", Name = "deleted", DbType = "Bit", CanBeNull = false)] 
public bool deleted ...

而不是：

[Column(Storage = "_deleted", Name = "deleted", DbType = "SmallInt", CanBeNull = true)] 
public bool deleted ...

在不同类型上映射/转换Linq-to-Sql的问题

2 个答案: