c# - 在不同类型上映射/转换 Linq-to-Sql 的问题

Question

也许有人可以提供帮助。

我想在映射的 Linq 类上使用不同的数据类型。

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;
        }
    }

没问题。但是当我想为 bool 值添加一些逻辑时，就不行了，就像这样:

 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 bit.. 我需要在映射类中进行转换。

** 更新

根据 mmcteam 的说法，在未映射的方法中进行转换就可以了。 不太确定是否以这种方式使用 OR 映射，但它确实有效。

    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;
        }
    }

** 注意/问题

您不能在 linq 查询上使用未映射的方法!

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

导致不支持的sql异常。没有 where 条件，数据会得到正确的值。

Answer 1

或者只需向您的行类添加一个属性并将前一个属性转换为 bool。