Question

在我的核心数据模型中，我有两个实体：

InventoryItem
InventoryAction

InventoryItem具有以下属性：
属性：

@property (nonatomic, retain) NSNumber * allowsActions;
@property (nonatomic, retain) NSNumber * assetID;
@property (nonatomic, retain) NSNumber * inventoryObjectID;
@property (nonatomic, retain) NSString * objectDescription;
@property (nonatomic, retain) NSNumber * quantity;
@property (nonatomic, retain) NSNumber * retired;
@property (nonatomic, retain) NSString * serialNumber;

关系：

@property (nonatomic, retain) NSSet *action;

InventoryAction具有以下属性 属性：

@property (nonatomic, retain) NSDate * actionDate;
@property (nonatomic, retain) NSNumber * actionID;
@property (nonatomic, retain) NSString * actionLongValue;
@property (nonatomic, retain) NSString * actionShortValue;
@property (nonatomic, retain) NSString * notes;
@property (nonatomic, retain) NSNumber * userActionID;
@property (nonatomic, retain) NSString * userAuthorizingAction;
@property (nonatomic, retain) NSString * userPerformingAction;
@property (nonatomic, retain) NSNumber * userPerformingActionExt;
@property (nonatomic, retain) NSNumber * inventoryObjectID;

关系

@property (nonatomic, retain) InventoryItem *object;

现在您已掌握了所有这些信息，我将告诉您，CoreData模型中存储的所有值都来自JSON格式的Web服务。所有值都正确存储。

我遇到的问题是，当我从CoreData获取数据时，它只会带回唯一的值。

例如：最后一个InventoryItem有6个与之关联的操作：

＆＃34;＆＃34 ;,
＆＃34;＆＃34 ;,
＆＃34;看起来有点黏糊糊＆＃34;，
＆＃34;哦，上帝......为什么你会这样做你生病的无生命的物体＆＃34;，
＆＃34;现在一切都变得黏糊糊了＆＃34;，
＆＃34;一切看起来都很好＆＃34;

由于1和2具有相同的值，因此它仅检索值1,3,4,5和6.

以下是我用于获取数据的代码：

- (void)loadDetails
{
    _fetchRequest = [[NSFetchRequest alloc] init];
    _entity = [NSEntityDescription entityForName:@"InventoryObject" inManagedObjectContext:[self managedObjectContext]];
    _sort = [NSSortDescriptor sortDescriptorWithKey:@"inventoryObjectID" ascending:YES];
    _sortDescriptors = [[NSArray alloc]initWithObjects:_sort, nil];

    [_fetchRequest setEntity:_entity];
    [_fetchRequest setSortDescriptors:_sortDescriptors];

    NSError *error;
    _fetchedObjects = [[self managedObjectContext] executeFetchRequest:_fetchRequest error:&error];
    for (InventoryItem *inventoryItem in _fetchedObjects) {
        NSLog(@"Object Description: %@", [inventoryItem valueForKey:@"objectDescription"]);
        NSLog(@"Object ID: %@", [inventoryItem valueForKey:@"inventoryObjectID"]);
        InventoryAction *action = (InventoryAction *)inventoryItem.action;
        NSLog(@"Action Long Value: %@", [action valueForKey:@"actionLongValue"]);
        NSLog(@"Notes: %@", [action valueForKey:@"notes"]);

    }
}

以下是JSON返回：

[{"MediaInventoryObjectsId":1,"AssetId":15,"Quantity":1,"SerialNumber":"R45DFL5","Description":"Test Camera 1","AllowActions":true,"Retired":false,"Actions":[{"MediaInventoryActionsId":3,"MediaInventoryObjectsId":1,"UserPerformingActionExt":4444,"UserActionId":1,"ActionDate":"2014-05-19T15:31:45.6","UserPerformingAction":"myersb","UserAuthorizingAction":"mccroskeyl","Notes":null,"ActionShortValue":"OUT","ActionLongValue":"Check Out"},{"MediaInventoryActionsId":4,"MediaInventoryObjectsId":1,"UserPerformingActionExt":4444,"UserActionId":2,"ActionDate":"2014-05-19T15:31:45.6","UserPerformingAction":"myersb","UserAuthorizingAction":"mccroskeyl","Notes":"everything looks good","ActionShortValue":"IN","ActionLongValue":"Check In"}]},{"MediaInventoryObjectsId":2,"AssetId":15,"Quantity":2,"SerialNumber":"IDKMYBFFJILL","Description":"Vanilla Ice Cream","AllowActions":true,"Retired":false,"Actions":[]},{"MediaInventoryObjectsId":3,"AssetId":15,"Quantity":1,"SerialNumber":"R2D23P0","Description":"Droid Bee Box","AllowActions":true,"Retired":false,"Actions":[{"MediaInventoryActionsId":5,"MediaInventoryObjectsId":3,"UserPerformingActionExt":4444,"UserActionId":1,"ActionDate":"2014-05-20T14:48:29.53","UserPerformingAction":"myersb","UserAuthorizingAction":"mccroskeyl","Notes":null,"ActionShortValue":"OUT","ActionLongValue":"Check Out"},{"MediaInventoryActionsId":6,"MediaInventoryObjectsId":3,"UserPerformingActionExt":4444,"UserActionId":2,"ActionDate":"2014-05-20T14:48:29.58","UserPerformingAction":"myersb","UserAuthorizingAction":"mccroskeyl","Notes":"everything looks good","ActionShortValue":"IN","ActionLongValue":"Check In"},{"MediaInventoryActionsId":7,"MediaInventoryObjectsId":3,"UserPerformingActionExt":5555,"UserActionId":1,"ActionDate":"2014-05-20T14:48:29.6","UserPerformingAction":"farmer","UserAuthorizingAction":"mccroskeyl","Notes":null,"ActionShortValue":"OUT","ActionLongValue":"Check Out"},{"MediaInventoryActionsId":8,"MediaInventoryObjectsId":3,"UserPerformingActionExt":5555,"UserActionId":2,"ActionDate":"2014-05-20T14:48:29.6","UserPerformingAction":"farmer","UserAuthorizingAction":"mccroskeyl","Notes":"its all slimy now","ActionShortValue":"IN","ActionLongValue":"Check In"},{"MediaInventoryActionsId":9,"MediaInventoryObjectsId":3,"UserPerformingActionExt":6666,"UserActionId":1,"ActionDate":"2014-05-20T14:48:29.61","UserPerformingAction":"intern1","UserAuthorizingAction":"mccroskeyl","Notes":"it looks kinda slimy","ActionShortValue":"OUT","ActionLongValue":"Check Out"},{"MediaInventoryActionsId":10,"MediaInventoryObjectsId":3,"UserPerformingActionExt":6666,"UserActionId":2,"ActionDate":"2014-05-20T14:48:29.62","UserPerformingAction":"intern1","UserAuthorizingAction":"mccroskeyl","Notes":"oh god....why would you do that to an inanimate object you sicko","ActionShortValue":"IN","ActionLongValue":"Check In"}]}]

我在某处读到NSSet可能只会带回唯一记录。这是真的，如果是这样，那么关系的解决方案是什么：action是NSSet？

Answer 1

您的关系声明如下：

@property (nonatomic, retain) NSSet *action;

但你这样访问它：

InventoryAction *action = (InventoryAction *)inventoryItem.action;

这是不正确的。 action关系是包含NSSet实例的InventoryAction，它本身不是InventoryAction。即使您将其分配给InventoryAction *，您实际拥有的是NSSet。然后你这样做：

NSLog(@"Notes: %@", [action valueForKey:@"notes"]);

如果您在valueForKey:上调用NSSet，则会返回该组中对象的该键的所有唯一值。在这种情况下，它会返回集合中notes个对象的InventoryAction属性的所有唯一值，这就是您所看到的。如果要查找每个实例而不是每个唯一值，则需要以下内容：

NSSet *actions = inventoryItem.action;
for (InventoryAction *action in actions) {
    NSLog(@"Action note: %@", action.note);
}

[警告，以上内容只是输入我的网页浏览器....]

核心数据和实体关系问题

1 个答案: