Question

我只是发布代码：

public IList<Dish> GetByNameDishTypes(IEnumerable<string> names,
    IEnumerable<string> dishTypes)
{
    // return dishes (ie food) whose name is in the names enumerable,
    // or whose type is in the dish types enumerables
    // (this would be 'breakfast', 'dinner') ..

    var namesArr = names != null ? names.ToArray() : new string[0];
    var dishTypesArr = dishTypes != null ? dishTypes.ToArray() : new string[0];

    var criteria = this.Session.CreateCriteria<Dish>();
    criteria.CreateAlias("DishType", "dt");
    criteria.Add(
        Restrictions.Or
        (
            Restrictions.In("Name", namesArr),
            Restrictions.In("dt.Name", dishTypesArr)
        ));

    return criteria.List<Dish>();

    /* get this to work?
    Dish d = null;
    DishType dt = null;
    return this.Session.QueryOver<Dish>(() => d)
        .JoinAlias(() => d.DishType, () => dt)
        .Where(
            Restrictions.Or
            (
                Restrictions.In(d.Name, namesArr),
                Restrictions.In(dt.Name, dishTypesArr)
            ))
        .List<Dish>(); */
}

所以，我想知道如何使用QueryOver执行此操作。我发布的这个QueryOver代码抛出一个空引用异常。标准代码有效。

谢谢：）

Answer 1

在QueryOver中有几种方法可以重写它，但最干净的可能是：

Dish d = null;
DishType dt = null;
return this.Session.QueryOver<Dish>(() => d)
    .JoinAlias(() => d.DishType, () => dt)
    .Where(() => d.Name.IsIn(namesArr) || dt.Name.IsIn(dishTypesArr))
    .List<Dish>();

这将生成如下所示的SQL：

SELECT this_.*
FROM   [Dish] this_
       inner join [DishType] dt1_
         on this_.DishTypeId = dt1_.Id
WHERE  (this_.Name in (/* Comma separated list of names */)
         or dt1_.Name in (/* Comma separated list of types */))

nhibernate queryover使用where-or子句加入别名

1 个答案: