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我不希望 FetchRequest 返回[QuestionCD]数组。FetchRequest 不能返回QuestionCD给我吗？

每个测试都有一个唯一的标题。一次测试总共有 50 道题。这里的标题决定了问题的类别。

使用此功能，我根据所选测试的标题保存该测试的问题。

我的核心数据模型错了吗？我想按标题对每个测试进行分类。我希望根据搜索的标题将问题返回给我。例如：“标题：八月测试 2”。请查看我的 json 构造和 coreData 模型。

保存分类功能：

func saveSelectedCategory(title: String) {
        let allCategory = QuestionCD(context: persistentContainer.viewContext)
        allCategory.title = title
        do {
            try persistentContainer.viewContext.save()
        } catch {
            print("Failed to save selected category: \(error.localizedDescription)")
        }
    }

保存类别后，我将问题以数组的形式传递到同一模型中的问题参数中并保存。

保存问题功能：

[QuestionList]是我的定制模型。我正在使用这个模型将我从 json 得到的问题保存到 CoreData。

func saveSelectedQuestion(questions: [QuestionList]) {
        
        let question = QuestionCD(context: persistentContainer.viewContext)
        question.questions = questions
        
        do {
            try persistentContainer.viewContext.save()
        } catch {
            print("Failed to save selected category: \(error.localizedDescription)")
        }
    }

获得选定的问题：

这里我根据选中的标题在QuestionCD中查找选中标题的类别。您可以查看 json 构造。例如标题：“Ağustos 测试 2”

我不希望返回结果是"[QuestionCD]". 我希望返回的结果是QuestionCD. 这可能吗 ？

您可以从 Core Data Entites 图像中检查 QuestionCD 模型。 如果 QuestionCD 不是数组，我可以在单个 ForEach 中运行它来获取问题。

func getSelectedQuestion(questionID: String) -> [QuestionCD] {
        let fetchRequest: NSFetchRequest<QuestionCD> = QuestionCD.fetchRequest()
        let search = NSPredicate(format: "title CONTAINS %@", questionID)
        print("search: \(search)")
        fetchRequest.predicate = search
        do {
            return try persistentContainer.viewContext.fetch(fetchRequest)
        } catch {
            return []
        }
    }

在此处输入图像描述

核心数据实体：

在此处输入图像描述

JSON：

{
  "allQuiz": [
    {
      "title":"Ağustos Test 1",
      "questions": [
        {
          "id": "1",
          "question":"Şekle göre aşağıdakiler hangisi doğrudur",
          "isQuestionImage": true,
          "isSectionImage": false,
          "imageURL":"https://firebasestorage.googleapis.com/v0/b/ehliyet-sinavim-01.appspot.com/o/Agustos%20Test%201%2F1.png?alt=media&token=2881447c-9081-4b13-a7ad-3ad097886b04",
          "sections": {
            "A":"2 numaralı aracın öncelikle geçmesi",
            "B":"1 numaralı aracın hızını arttırarak kavşağa girmesi",
            "C":"2 numaralı aracın 3 numaralı aracın geçmesini beklemesi",
            "D":"3 numaralı aracın 2 numaralı aracı ikaz ederek durdurması"
          },
          "selected":"",
          "correct": "A"
        },
        {
          "id": "2",
          "question":"Akaryakıt istasyonundan yola çıkmak isteyen şekildeki 2 numaralı araç sürücüsü ne yapmalıdır ?",
          "isQuestionImage": true,
          "isSectionImage": false,
          "imageURL":"https://firebasestorage.googleapis.com/v0/b/ehliyet-sinavim-01.appspot.com/o/Agustos%20Test%201%2F2.jpg?alt=media&token=94b833ff-3462-445a-9054-94b3cdaaa668",
          "sections": {
            "A":"Selektör yaparak 1 numarlı aracı durdurmalıdır.",
            "B":"Korna çalıp 1 numralı aracı yavaşlatmalıdır.",
            "C":"1 numaralı aracın geçmesini beklemelidir.",
            "D":"Geçiş hakkını kendi kullanmalıdır."
          },
          "selected":"",
          "correct": "C"
        },
        ...........
      ]
    },
    {
      "title":"Ağustos Test 2",
      "questions": [
        {
          "id": "1",
          "question":"Şekle göre aşağıdakiler hangisi doğrudur",
          "isQuestionImage": true,
          "isSectionImage": false,
          "imageURL":"https://firebasestorage.googleapis.com/v0/b/ehliyet-sinavim-01.appspot.com/o/Agustos%20Test%201%2F1.png?alt=media&token=*****-a7ad-3ad097886b04",
          "sections": {
            "A":"2 numaralı aracın öncelikle geçmesi",
            "B":"1 numaralı aracın hızını arttırarak kavşağa girmesi",
            "C":"2 numaralı aracın 3 numaralı aracın geçmesini beklemesi",
            "D":"3 numaralı aracın 2 numaralı aracı ikaz ederek durdurması"
          },
          "selected":"",
          "correct": "A"
        },
        {
          "id": "2",
          "question":"Akaryakıt istasyonundan yola çıkmak isteyen şekildeki 2 numaralı araç sürücüsü ne yapmalıdır ?",
          "isQuestionImage": true,
          "isSectionImage": false,
          "imageURL":"https://firebasestorage.googleapis.com/v0/b/ehliyet-sinavim-01.appspot.com/o/Agustos%20Test%201%2F2.jpg?alt=media&token=*****-9054-94b3cdaaa668",
          "sections": {
            "A":"Selektör yaparak 1 numarlı aracı durdurmalıdır.",
            "B":"Korna çalıp 1 numralı aracı yavaşlatmalıdır.",
            "C":"1 numaralı aracın geçmesini beklemelidir.",
            "D":"Geçiş hakkını kendi kullanmalıdır."
          },
          "selected":"",
          "correct": "C"
        },
        ...........
      ]
    }
  ]
}

模型：

class QuestionContainer: NSObject, Codable{
    
    var questions: Question
    
    init(questions: Question) {
        self.questions = questions
    }
}

class Question: NSObject, Codable {
    
    var title: String
    var questions: [QuestionList]
    
    init(title: String, questions: [QuestionList]) {
        self.title = title
        self.questions = questions
    }
}

public class QuestionList: NSObject, Codable {
    
    var id: String
    var question: String
    var isQuestionImage, isSectionImage: Bool
    var imageURL: String
    var imageData: Data?
    var sections: [QuestionSections.RawValue : String]
    var selected: String
    var correct: String
    
    init(id: String, question: String, isQuestionImage: Bool, isSectionImage: Bool, imageURL: String, sections: [QuestionSections.RawValue : String], selected: String, correct: String) {
        self.id = id
        self.question = question
        self.isQuestionImage = isQuestionImage
        self.isSectionImage = isSectionImage
        self.imageURL = imageURL
        self.sections = sections
        self.selected = selected
        self.correct = correct
    }
}

核心数据管理器：

class CoreDataManager: ObservableObject {
    let persistentContainer: NSPersistentContainer
    
    init() {
        persistentContainer = NSPersistentContainer(name: "EhliyetSinavim")
        persistentContainer.loadPersistentStores { description, error in
            if let error = error {
                fatalError("Core Data Stre failed: \(error.localizedDescription)")
            }
        }
    }
    
    func saveSelectedCategory(title: String) {
        let allCategory = QuestionCD(context: persistentContainer.viewContext)
        allCategory.title = title
        do {
            try persistentContainer.viewContext.save()
        } catch {
            print("Failed to save selected category: \(error.localizedDescription)")
        }
    }
    
    func getSelectedCategory() -> [QuestionCD] {
        let fetchRequest: NSFetchRequest<QuestionCD> = QuestionCD.fetchRequest()
        let sort = NSSortDescriptor(key: "title", ascending: true)
        fetchRequest.sortDescriptors = [sort]
        do {
            return try persistentContainer.viewContext.fetch(fetchRequest)
        } catch {
            return []
        }
    }
    
    func searchInCategory(text: String) -> [QuestionCD] {
        let fetchRequest: NSFetchRequest<QuestionCD> = QuestionCD.fetchRequest()
        let search = NSPredicate(format: "ANY title == %@", text)
        print("search: \(search)")
        fetchRequest.predicate = search
        print("request predicate: \(String(describing: fetchRequest.predicate))")
        do {
            return try persistentContainer.viewContext.fetch(fetchRequest)
        } catch {
            print("ver bulunamadı \n")
            return []
        }
    }
    
    //MARK: ForQuestionCategory
    func saveSelectedQuestion(title: String, questions: [QuestionList]) {
        
        let question = QuestionCD(context: persistentContainer.viewContext)
        question.title = title
        question.questions = questions
        
        do {
            try persistentContainer.viewContext.save()
        } catch {
            print("Failed to save selected category: \(error.localizedDescription)")
        }
    }
    
    func getSelectedQuestion(questionID: String) -> [QuestionCD] {
        let fetchRequest: NSFetchRequest<QuestionCD> = QuestionCD.fetchRequest()
        let search = NSPredicate(format: "title CONTAINS %@", questionID)
        print("search: \(search)")
        fetchRequest.predicate = search
        do {
            return try persistentContainer.viewContext.fetch(fetchRequest)
        } catch {
            return []
        }
    }
}
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1 回答 1

0

您可以从获取的对象数组中返回第一个对象：

func getSelectedQuestion(questionID: String) -> QuestionCD? {
    let fetchRequest: NSFetchRequest<QuestionCD> = QuestionCD.fetchRequest()
    let search = NSPredicate(format: "title CONTAINS %@", questionID)
    print("search: \(search)")
    fetchRequest.predicate = search
    do {
        return try persistentContainer.viewContext.fetch(fetchRequest).first
    } catch {
        return nil
    }
}
于 2021-08-20T08:43:22.377 回答