c# - 使用 NHibernate 的自定义 Linq 生成器 (AddDays)

Question

我试图在 NHibernate 中包含 AddDays，就像那样:

public class ExtendedLinqtoHqlGeneratorsRegistry : DefaultLinqToHqlGeneratorsRegistry
{
    public ExtendedLinqtoHqlGeneratorsRegistry()
    {
        this.Merge(new AddDaysGenerator());
    }
}

public class AddDaysGenerator : BaseHqlGeneratorForMethod
{
    public AddDaysGenerator()
    {
        SupportedMethods = new[]
            {
                ReflectionHelper.GetMethodDefinition<DateTimeOffset?>(d => d.Value.AddDays((double) 0))
            };
    }

    public override HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnlyCollection<Expression> arguments, HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)
    {
        return treeBuilder.MethodCall("AddDays", visitor.Visit(targetObject).AsExpression(), visitor.Visit(arguments[0]).AsExpression());
    }
}

public class MsSql2008CustomDialect : MsSql2008Dialect  
{
    public MsSql2008CustomDialect()
    {
        RegisterFunction("AddDays", new SQLFunctionTemplate(NHibernateUtil.DateTime, "dateadd(day,?2,?1)"));
    }
}

我的 NH 配置是:

configuration = new Configuration();

configuration.Proxy(p => p.ProxyFactoryFactory<DefaultProxyFactoryFactory>()).DataBaseIntegration(db =>
      {
            db.ConnectionStringName = "xxyy";
            db.Dialect<MsSql2008CustomDialect>();
       })
        .AddAssembly(typeof(myClass).Assembly)
        .CurrentSessionContext<LazySessionContext>()
        .LinqToHqlGeneratorsRegistry<ExtendedLinqtoHqlGeneratorsRegistry>();

尝试将其与谓词一起使用:

var predicate = PredicateBuilder.False<myClass>();
if(...)
     predicate = predicate.Or(i => i.MyDate.AddDays(date) > DateTime.Today);

但它不起作用...我总是遇到同样的错误:

System.NotSupportedException: System.DateTime AddDays(Double)
at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.VisitMethodCallExpression(MethodCallExpression expression)

知道我做错了什么吗？

谢谢

Answer 1

如评论中所述，您应该检查 MyClass.MyDate 是否属于 Nullable DateTimeOffset 类型，这是您的 AddDays 的目标类型> 声明:

SupportedMethods = new[]
    {
        ReflectionHelper.GetMethodDefinition<DateTimeOffset?>
                                             (d => d.Value.AddDays((double) 0))
    };