Lala's Program Note 實作記錄: 3.建立資料模型

since: 2011/08/27
update: 2011/08/29

A. 說明:
   1. Core Data manages an object graph using real object references. It has no need
      for a unique autoincrement identifier that can be used as a primary key in the
      same sense it would be used in a relational database.
      備註: a. 譯: Core Data 使用真實的物件參照來管理物件圖表, 因此不需要像
                        關聯式資料庫那樣使用自動新增的獨一無二 ID 來當主鍵.
               b. Core Data is not a database; it's an object graph persistence framework.

   2. All Core Data attributes must have a class type.
      ex: Entity: Organization
            Attribute: id (with type: Integer 16)
            // a. create a primitive int from the hash of the organization object
            NSManagedObject *organization = ....;
            int orgID = [organization hash]; 
         
            // b. convert the primitive int into an NSNumber object,
            // which can be used in the setValue:forKey: method.
            [organization setValue:[NSNumber numberWithInt:orgID] forKey:@"id"];

   3. Core Data returns the "many" side of a one-to-many relationship as a set(NSSet).
      ex: add some employees to the relationship
           NSManagedObject *john = ....;
           NSManagedObject *jane = ....;
           NSManagedObject *bill = ....;
        
          NSMutableSet *johnsEmployees = [john mutableSetValueForKey:@"employees"];

          [johnsEmployees addObject:jane];
          [johnsEmployees addObject:bill];


B. 資料模型規劃:
   Entity:
   NoteBook ----> 筆記本

   Attributes:
   name (type: string) ----> 筆記本名稱(必要)
   subName (type: string) ----> 筆記本副名稱(非必要)
   articleCount (type: int 16) ----> 文章數量(必要, 預設值:0)
   type (type: int 16) ----> 種類(系統預設的, 使用者新增的), (必要, 預設值:0)
   dateCreated (type: Date) ----> 建立日期 (非必要)
   dateUpdate (type: Date) ----> 更新日期 (非必要)
   status (type: int 16) ----> 筆記本狀態 (正常, 刪除), (必要, 預設值:1)
   flag (type: int 16) ----> 備用旗標, (非必要, 預設值:0)
   ---------------------------------------------------------------------------------------------------------------
   Entity:
   NoteArticle ----> 筆記文章

   Attributes:  
   title (type: string) ----> 英文標題(或使用者新增的) (必要, indexed)
   titleC (type: string) ----> 中文標題 (非必要, indexed)
   subTitle (type: string) ----> 副標題 (非必要)
   content (type: string) ----> 英文內容(或使用者新增的) (必要)
   contentC (type: string) ----> 中文內容 (非必要)
   readCount (type: int 16) ----> 文章讀取次數, (必要, 預設值:0)
   favorite (type: Boolean) ----> 是否為我的最愛, (必要, 預設值:NO)
   type (type: int 16) ----> 文章種類(系統預設的, 使用者新增的), (必要, 預設值:0)
   version (type: string) ----> 適用的版本 (非必要)
   memo (type: string) ----> 備註攔 (非必要)
   dateCreated (type: Date) ----> 建立日期 (非必要)
   dateUpdate (type: Date) ----> 更新日期 (非必要)
   status (type: int 16) ----> 文章狀態 (正常, 刪除), (必要, 預設值:1)
   flag (type: int 16) ----> 備用旗標, (非必要, 預設值:0)
   ---------------------------------------------------------------------------------------------------------------
   Relationship:
   from: NoteBook
   Name: articles
   Destination: NoteArticle
   Properties: Optional
   Plural: To-Many Relationship (一對多)
   Delete Rule: Cascade (瀑布似地)
   ---------------------------------------------------------------------------------------------------------------
   Relationship:
   from: NoteArticle
   Name: book
   Destination: NoteBook
   Inverse: articles
   Properties: Optional
   Delete Rule: Nullify (廢棄)


C. 建立完成: