是否有像LINQ一样的QueryOver查询生成器或扩展点？
是否有像LINQ一样的QueryOver查询生成器或扩展点？
提问于 2013-05-01 13:16:54
我正在尝试使用与Query<T>()一起在QueryOver<T>()中使用的计算属性。当使用LINQ查询时，我可以使用自定义DefaultLinqToHqlGeneratorsRegistry注册自定义生成器。这对于从表达式中计算的属性非常有用，所以代码不会被复制。
我似乎找不到为QueryOver API注册自定义生成器的扩展点。它存在吗？
我不想在原始string (Map(x => x.Prop).Formula("query").LazyLoad().Access.ReadOnly())中重复计算的属性逻辑。这意味着两倍的逻辑和两倍的测试次数。
根据我在来源中看到的，QueryOver API使用QueryOver作为它的基础.它直接转换为原始SQL，而不是HQL。
回答 2
Stack Overflow用户
回答已采纳
发布于 2013-05-06 11:15:56
Linq和QueryOver采用不同的路径来实现sql：
QueryOver -> Expression -> Criteria \
Linq -> LinqParser -> Hql --> Sql对于标准，有NHibernate.Impl.ExpressionProcessor.RegisterCustomMethodCall(...);，这可能是您想要的。
一个简单的例子：
public static class QueryOverExtensions
{
public static void Register()
{
ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Day(default(DateTime)), QueryOverExtensions.ProcessDay);
ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Month(default(DateTime)), QueryOverExtensions.ProcessMonth);
ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Year(default(DateTime)), QueryOverExtensions.ProcessYear);
}
public static Int32 Day(this DateTime dateTimeProperty)
{
return (dateTimeProperty.Day);
}
public static Int32 Month(this DateTime dateTimeProperty)
{
return (dateTimeProperty.Month);
}
public static Int32 Year(this DateTime dateTimeProperty)
{
return (dateTimeProperty.Year);
}
private static IProjection ProcessDay(MethodCallExpression methodCallExpression)
{
IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection();
return (Projections.SqlFunction("day", NHibernateUtil.Int32, property));
}
private static IProjection ProcessMonth(MethodCallExpression methodCallExpression)
{
IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection();
return (Projections.SqlFunction("month", NHibernateUtil.Int32, property));
}
private static IProjection ProcessYear(MethodCallExpression methodCallExpression)
{
IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection();
return (Projections.SqlFunction("year", NHibernateUtil.Int32, property));
}
}不要忘了调用注册表()。之后，您可以这样使用它：
session.QueryOver<Order>().Where(o => o.Date.Month() == DateTime.Today.Month).List();Stack Overflow用户
发布于 2013-05-15 16:40:33
一个简单的例子：
public static class QueryOverExtensions
{
public static void Register()
{
ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Day(default(DateTime)), QueryOverExtensions.ProcessDay);
ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Month(default(DateTime)), QueryOverExtensions.ProcessMonth);
ExpressionProcessor.RegisterCustomProjection(() => QueryOverExtensions.Year(default(DateTime)), QueryOverExtensions.ProcessYear);
}
public static Int32 Day(this DateTime dateTimeProperty)
{
return (dateTimeProperty.Day);
}
public static Int32 Month(this DateTime dateTimeProperty)
{
return (dateTimeProperty.Month);
}
public static Int32 Year(this DateTime dateTimeProperty)
{
return (dateTimeProperty.Year);
}
private static IProjection ProcessDay(MethodCallExpression methodCallExpression)
{
IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection();
return (Projections.SqlFunction("day", NHibernateUtil.Int32, property));
}
private static IProjection ProcessMonth(MethodCallExpression methodCallExpression)
{
IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection();
return (Projections.SqlFunction("month", NHibernateUtil.Int32, property));
}
private static IProjection ProcessYear(MethodCallExpression methodCallExpression)
{
IProjection property = ExpressionProcessor.FindMemberProjection(methodCallExpression.Arguments[0]).AsProjection();
return (Projections.SqlFunction("year", NHibernateUtil.Int32, property));
}
}不要忘了调用注册表()。之后，您可以这样使用它：
session.QueryOver<Order>().Where(o => o.Date.Month() == DateTime.Today.Month).List();页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/16318843
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