Swift 如何在领域中进行嵌套查询

我有一个领域：

class Train: RLMObject {
    dynamic var stationDeparture: Station?
    dynamic var trainId = 0
    dynamic var route = RLMArray(objectClassName: Route.className())
    override class func primaryKey() -> String {
        return "trainId"
    }
}
class Route: RLMObject {
    dynamic var numberInRoute = 0
    dynamic var station: Station?
    var owners: [Train] {
        return linkingObjectsOfClass("Train", forProperty: "Route") as! [Train]
    }
}
class Station: RLMObject {
    dynamic var code = 0
    dynamic var name = ""
    override class func primaryKey() -> String {
        return "code"
    }
    dynamic var relatedStations = RLMArray(objectClassName: Station.className())
}

我试着在

动态var车站的
类Train:RLMObject
中获取车站和车站相关车站的所有列车部分：车站？

。首先，我从相关站点的代码中生成一个字符串，然后使用“IN”IN谓词进行查询

此函数有效，但它有效！：

func trainsForDepartureStation (station: Int) -> RLMResults? {
    let stations = Station.objectsWhere("code == \(station)")
    let related = stations.lastObject() as! Station
    if related.relatedStations.count > 0 {
        var st = ""
        st += "{\(station)"
        for id in 0...related.relatedStations.count-1 {
            st += ", \(related.relatedStations[id].code)"
        }
        st += "}"
        let trains = Train.objectsWhere("stationDeparture.code IN \(st)")

        return trains

    } else {
        let trains = Train.objectsWhere("stationDeparture.code == \(station)")
        return trains
    }
}

但当我试着用同样的方法让列车在所有路线上的所有车站都运行时，它并没有起作用

let trains=Train.objectsWhere（“ANY route.station.relatedStations.code IN\（st）”）

错误在于：

'Invalid predicate', reason: 'Predicate with ANY modifier must compare a KeyPath with RLMArray with a value'

如何对此问题进行嵌套查询？

---

我不熟悉swift、objective-С和realm（

您可能已经猜到了，您必须将该查询分解为多个查询。不过，首先，让我们重构

trainsForDepartureStation（）

，以更好地了解它当前正在做什么：

func trainsForDepartureStation(station: Int) -> RLMResults? {
  let stations = Station.objectsWhere("code == \(station)")
  if let related = stations.lastObject() as? Station where related.relatedStations.count > 0 {
    return Train.objectsWhere("stationDeparture IN %@", related.relatedStations)
  } else {
    return Train.objectsWhere("stationDeparture.code == \(station)")
  }
}

好的，现在让我们将其更改为返回“所有列车路线上所有车站的列车”：

---

只有一个错误，这部分：

    let allRelatedStations = Station.objectsWhere("relatedStations IN %@", related.relatedStations)
    let allRelatedRoutes = Route.objectsWhere("station IN %@", allRelatedStations)

应替换为：

    let allRelatedRoutes = Route.objectsWhere("station IN %@", related.relatedStations)

---

因为allRelatedStations没有获取相关站点，但再次仅获取父站点）

这适用于仅具有相关站点的路由，如果父站点和相关站点都存在路由，如何连接此结果？将这两个查询与“或”组合以连接。

    let allRelatedRoutes = Route.objectsWhere("station IN %@", related.relatedStations)