nHibernate欧元符号€更改为字符¿ [英] nHibernate Euro symbol € change for character ¿

问题描述

我尝试使用NHibernate和FluentNHibernate在数据库Oracle 11g中保存欧元符号€.

I've tried save a Euro Symbol € using NHibernate and FluentNHibernate in a database Oracle 11g.

我已经检查了NHibernate的日志，并看到了生成的sql语句:

I have checked a log from NHibernate and see the generated sql statement:

UPDATE CURRENCY
SET    DESCRIPTION = 'Euro',
       SYMBOL = '€',
WHERE  ID = 63

执行表 CURRENCY 中的查询时，列 SYMBOL 会返回¿

When the query from table CURRENCY execute, the column SYMBOL returns ¿

我尝试使用 AnsiString 更改 SYMBOL 列的FluentNHibernate映射，如下所示:

I've tried change the FluentNHibernate Mapping for the column SYMBOL using AnsiString, like this:

Map((x) => x.Symbol).Column("SYMBOL").CustomType("AnsiString").Not.Nullable();

但这是行不通的.

我也尝试更改 NVARCHAR2 的列类型，并更改以下内容的FluentNHibernate映射:

I tried too change type of column for NVARCHAR2 and change FluentNHibernate Mapping for:

Map((x) => x.Symbol).Column("SYMBOL").CustomSqlType("NVARCHAR2").Not.Nullable();

但是它也不起作用.

我如何使其正常工作?

推荐答案

如果数据库中的所有字符串都是NVARCHAR2，则可以对应用程序中的所有字符串使用NVARCHAR2(否则，由于转换为VARCHAR2，您可能会遇到性能问题)-但是您至少需要NHibernate 5.0.在NHibernate配置中将此属性设置为true:oracle.use_n_prefixed_types_for_unicode

You could use NVARCHAR2 for all strings in your app if they are all NVARCHAR2 in the DB (otherwise you might get performance problems because of conversions to VARCHAR2) - but you need at least NHibernate 5.0 for it. Set this prop in NHibernate config to true: oracle.use_n_prefixed_types_for_unicode

nHibernateConfig.SetProperty("oracle.use_n_prefixed_types_for_unicode", "true");

如果混合使用VARCHAR2和NVARCHAR2列，一个更好的解决方案是对NVARCHAR2列/属性使用自定义类型:

A better solution, if you have mixed VARCHAR2 and NVARCHAR2 columns, is to use a custom type for NVARCHAR2 columns/properties:

public class UnicodeStringType : IUserType
{
    public bool Equals(object x, object y)
    {
        if (ReferenceEquals(x, y)) return true;
        if (x == null || y == null) return false;
        return x.Equals(y);
    }

    public int GetHashCode(object x)
    {
        return x.GetHashCode();
    }

    public object NullSafeGet(IDataReader rs, string[] names, object owner)
    {
        var value = NHibernateUtil.String.NullSafeGet(rs, names[0]) as string;
        return value;
    }

    public void NullSafeSet(IDbCommand cmd, object value, int index)
    {
        var parameter = (IDataParameter)cmd.Parameters[index];
        ((OracleParameter)parameter).OracleDbType = OracleDbType.NVarchar2;
        parameter.Value = value;
    }

    public object DeepCopy(object value)
    {
        return value;
    }

    public object Replace(object original, object target, object owner)
    {
        return original;
    }

    public object Assemble(object cached, object owner)
    {
        return DeepCopy(cached);
    }

    public object Disassemble(object value)
    {
        return DeepCopy(value);
    }

    public SqlType[] SqlTypes => new[] { new SqlType(DbType.String) };
    public Type ReturnedType => typeof(string);
    public bool IsMutable => false;
}

您可以在映射中像这样使用它:

You use it like this in mappings:

Map((x) => x.Symbol).Column("SYMBOL").CustomType<UnicodeStringType>().Not.Nullable();

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