过滤器正在返回具有匹配孩子的父母的所有孩子

Posted 2023-03-04

【中文标题】过滤器正在返回具有匹配孩子的父母的所有孩子

【英文标题】：Filter is returning all children for parent with matching child

【发布时间】：2017-05-25 21:29:36

【问题描述】：

我正在使用 Realm for Swift，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位置，以便仅显示与给定邮政编码匹配的位置。我就是这样做的

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在一个特定类别下的公司中搜索。

我遇到的问题是它会返回具有匹配位置的公司的所有位置。因此，如果我要查找的 zip 为 12345，并且 companyA 有一个匹配的位置，则返回 companyA 下的所有位置，即使它们不匹配。

如何将结果限制为仅匹配的位置？

【参考方案1】：

如何将结果限制为仅匹配的位置？

现在您正在返回 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，然后在领域中查询Locations 匹配zip == '12345' && ANY parentCompanies.parentNavigation.key == 4。

这是一个演示此功能的示例应用：

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
    

打印出来：

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

    );
  
)

【讨论】：

我可以使用它，但理想情况下，我希望它也拥有“拥有”这些位置的公司，以便用户知道他们正在查看的公司。有很多类似名称的位置，例如“总办公室”。

简单：locationsIn12345AndNavigationKey4.flatMap $0.parentCompanies

你能让这对代码更友好吗？这应该是进入过滤器的字符串是这些实际的函数调用吗？我认为这也必须通过反向关系来完成？

我不懂这些问题。你能改写一下吗？

您所做的评论，locationsIn12345AndNavigationKey4.flatMap $0.parentCompanies ，应该作为字符串进入filter() 函数，还是代码？如果是这样，我将其附加到什么？