Question

我有以下代码，它将用来自struct数组的条目填充核心数据库。当我调试时，似乎可以正确地将数据发送到func iterateCoreData函数，但是当我尝试获取结果时，我什么也没得到。

未将数据添加到数据库或无法获取数据可能是错误的。

我尝试了使用普通数组进行保存和获取的主要语法，

            let managedObjectContext = self.persistentContainer.viewContext

            // this is the working method to save data to core data and then fetch it.
            /*
            guard let entity = NSEntityDescription.entity(forEntityName: "Journal", in: managedObjectContext) else {
                fatalError("There is no such entity!")
            }

            let count = journalNoteArray.id.count

            for i in 0..<count {
                let data = NSManagedObject(entity: entity, insertInto: managedObjectContext)

                data.setValue(journalNoteArray.id[i], forKey: "id")
                data.setValue(journalNoteArray.date[i], forKey: "date")
                data.setValue(journalNoteArray.journal[i], forKey: "journal")
                data.setValue(journalNoteArray.userID[i], forKey: "userID")
                data.setValue(journalNoteArray.editDate[i], forKey: "editDate")
            }

            let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Journal")
            fetchRequest.sortDescriptors = [NSSortDescriptor.init(key: "id", ascending: true)]

            do {
                if let results = try managedObjectContext.fetch(fetchRequest) as? [NSManagedObject] {
                    for result in results {
                        if let id = result.value(forKey: "id") as? Int, let date = result.value(forKey: "date"), let note = result.value(forKey: "journal") {
                            print("the id is: \(id), the date entered is: \(date) and the note is: \(note)")
                        }
                    }
                }
            } catch {
                print("there was an error fetching the results")
            }
            */

            let journalMirror = Mirror(reflecting: journalNoteArray)

            for journal in journalMirror.children {

                self.iterateCoreData(givenArray: (journal.value as? Array)!, recEntity: "Journal", recKey: journal.label!)

            }

            let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Journal")

            do {
                if let results = try managedObjectContext.fetch(fetchRequest) as? [NSManagedObject] {
                    for result in results {
                        if let id = result.value(forKey: "id") as? Int, let date = result.value(forKey: "date"), let journal = result.value(forKey: "journal") {
                            print("the id is: \(id) created on date: \(date) with note: \(journal)")
                        }
                    }
                }
            } catch {
                print("there was an error fetching the results")
            }


        }

和iterateCoreData函数如下：

func iterateCoreData(givenArray: Array<Any>, recEntity: String, recKey: String) {

    let managedObjectContext = self.persistentContainer.viewContext

    guard let entity = NSEntityDescription.entity(forEntityName: recEntity, in: managedObjectContext) else {
        fatalError("There is no such entity!")
    }

    for entry in givenArray {
        let data = NSManagedObject(entity: entity, insertInto: managedObjectContext)

        print(recKey, entry)
        data.setValue(entry, forKey: recKey)
    }

}

问题是我需要逐行保存在数据库中，而不是每个实体的每个属性保存。我该如何解决？

无法获取核心数据的条目

0 个答案: