过滤器正在返回具有匹配子项的父项的所有子项

Question

我正在为 Swift 使用 Realm，我的结构如下：

class Navigation: Object {

    dynamic var key = 0
    dynamic var title: String?
    let companies = List<Companies>()

    override static func primaryKey() -> String? {
        return "key"
    }
}

class Companies: Object {

    dynamic var key = 0
    dynamic var name: String?
    let locations = List<Locations>()

    override static func primaryKey() -> String? {
        return "key"
    }
}

class Locations: Object {

    dynamic var key = 0
    ...
    dynamic var zip: String?
    let contacts = List<Contacts>()

    override static func primaryKey() -> String? {
        return "key"
    }
}

class Contacts: Object {

    dynamic var key = 0
    dynamic var firstName: String?
    dynamic var lastName: String?
    ...

    override static func primaryKey() -> String? {
        return "key"
    }
}

我正在尝试按邮政编码过滤掉位置，以便仅显示与给定邮政编码匹配的位置。我是这样做的

companies = realm.objects(Navigation.self).filter("key = 4").first!.companies.filter(predicate).sorted(byKeyPath: "key")

key = 4 位是因为过滤器应该只搜索某一特定类别下的公司。

我遇到的问题是 returns 具有匹配位置的公司的所有位置。因此，如果我要查找的邮编是 12345，并且 companyA 有匹配的位置，则将返回 companyA 下的所有位置，即使它们不匹配也是如此。

如何将结果限制为只有个匹配的位置？

Answer 1

How can I limit the results to be only locations with a match?

现在您要返回一个 Results<Companies>，但您似乎想要位置。我通过向 Companies 和 Locations 模型添加一些反向关系属性来完成我认为您正在寻找的东西，然后查询 Realm 以查找 Locations 匹配 zip == '12345' && ANY parentCompanies.parentNavigation.key == 4。

下面是一个演示这一点的示例应用程序：

import UIKit
import RealmSwift

class Navigation: Object {

    dynamic var key = 0
    dynamic var title: String?
    let companies = List<Companies>()

    override static func primaryKey() -> String? {
        return "key"
    }
}

class Companies: Object {

    dynamic var key = 0
    dynamic var name: String?
    let locations = List<Locations>()
    let parentNavigation = LinkingObjects(fromType: Navigation.self, property: "companies")

    override static func primaryKey() -> String? {
        return "key"
    }
}

class Locations: Object {

    dynamic var key = 0
    // ...
    dynamic var zip: String?
    let contacts = List<Contacts>()
    let parentCompanies = LinkingObjects(fromType: Companies.self, property: "locations")

    override static func primaryKey() -> String? {
        return "key"
    }
}

class Contacts: Object {

    dynamic var key = 0
    dynamic var firstName: String?
    dynamic var lastName: String?
    // ...

    override static func primaryKey() -> String? {
        return "key"
    }
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        _ = try? FileManager.default.removeItem(at: Realm.Configuration.defaultConfiguration.fileURL!)
        let realm = try! Realm()

        // Objects Matching Query
        try! realm.write {
            // Locations
            let locations = Locations()
            locations.zip = "12345"

            // Companies
            let companies = Companies()
            companies.name = "Companies A"
            companies.locations.append(locations)

            // Nav
            let nav = Navigation()
            nav.key = 4
            nav.companies.append(companies)

            // Add to Realm
            realm.add(nav)
        }

        let locationsIn12345AndNavigationKey4 = realm.objects(Locations.self)
            .filter("zip == '12345' && ANY parentCompanies.parentNavigation.key == 4")
        print(locationsIn12345AndNavigationKey4)

        return true
    }
}

这会打印：

Results<Locations> (
  [0] Locations {
    key = 0;
    zip = 12345;
    contacts = RLMArray <0x6000000f2100> (

    );
  }
)

过滤器正在返回具有匹配子项的父项的所有子项

Filter is returning all children for parent with matching child

filtering

realm

nspredicate

swift