将字符串设置为"varchar"的sql类型而不是"nvarchar"

Question

我有以下映射:

public class LogEntryMap
{
    public LogEntryMap()
    {
        Map.Id(x => x.Id).GeneratedBy.Identity();
        Map(x => x.Context).CustomSqlType("varchar").Length(512);
    }
}

但是,使用SchemaExport在SQL Server 2008中生成数据库时,生成的脚本会忽略长度,因此实际上它最终为varchar长度为1:

create table OV_SAC.dbo.[LogEntry] (
    Id BIGINT IDENTITY NOT NULL,
   Context varchar null,
   primary key (Id)
)

.CustomSqlType("varchar 512")抛出一个例外.并且没有定义CustomSqlType,字符串被映射到nvarchar(它确实尊重Length属性).

有什么建议？

Answer 1

使用.CustomType("AnsiString")而不是默认值"String"而NHibernate将使用varchar而不是nvarchar.

Answer 2

如果您希望将所有字符串映射到varchar而不是nvarchar,则可以考虑使用约定:

/// <summary>
/// Ensures that all of our strings are stored as varchar instead of nvarchar.
/// </summary>
public class OurStringPropertyConvention : IPropertyConvention
{
    public void Apply(IPropertyInstance instance)
    {
        if (instance.Property.PropertyType == typeof (string))
            instance.CustomType("AnsiString");
    }
}

然后,您的映射可以返回到简单的映射:

Map(x => x.Context);

只要确保你记得告诉Fluent NH使用这个约定:

        var configuration = new Configuration();
        configuration.Configure();
        Fluently
            .Configure(configuration)
            .Mappings(m => m.FluentMappings
                .AddFromAssemblyOf<Widget>()
                .Conventions.Add<OurStringPropertyConvention>()
                )
            .BuildSessionFactory();

Answer 3

卫生署.

Map(x => x.Context).CustomSqlType("varchar (512)");

create table OV_SAC.dbo.[LogEntry] (
    Id BIGINT IDENTITY NOT NULL,
   Context varchar (512) null,
   primary key (Id)
)