Core数据保存问题：无法更新可变属性（NSArray） [英] Core Data saving problem: can't update transformable attribute (NSArray)

问题描述

我在Core Data应用程式中有一个奇怪的问题。

我的应用程式中有三个实体，但今天我发现其中一个存在问题。我的问题实体叫做 Invoice ，它有很多属性，包括 Products 。它是NSDictionaries的NSArray编码（通过默认NSValueTransformer）。

一切正常 - 我创建我的发票，客户端，产品等。

但，当我从列表中选择发票，然后尝试修改其产品并点击保存按钮时，我的保存仅在我的应用获取

问题只在于我的产品数组 - 其余的（例如付款日期，客户等）

b

我通过

 传递发票 = [self.fetchedResultsController objectAtIndexPath：indexPath]; 
 invoiceEditor.invoice = inv; 
  

并保存我的数据（在我的 InvoiceEditor VC）：

  [self.invoice setValue：client forKey：@Client] // NSDictionary; 
 [self.invoice setValue：products forKey：@Products] // NSDictionaries的NSArray; 
 [self.invoice setValue：pmDate forKey：@PaymentDate] // NSDate; 
 //其他属性
 NSManagedObjectContext * context = self.invoice.managedObjectContext; 
 NSError * error = nil; 
 if（！[context save：& error]）{
 NSLog（@Unresolved error％@，％@，error，[error userInfo]）; 
 abort（）; Everythings保存直到被终止：客户端，产品，日期。
} 
  

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解决方案

p>刚刚发现问题。从模型对象实现指南：

如果有一个类的mutable和immutable版本，如NSArray和NSMutableArray - 你通常应该将get访问器的返回值声明为不可变对象，即使模型内部使用了一个可变对象。

而我的产品数组实际上是一个 NSMutableArray 实例。我通过复制 products 解决了（所以我将mutable数组转换为immutable数组）。现在它的工作。 :)我不需要开始赏金...

I have a strange problem in my Core Data app.

I have three entities in my app, but today I found a problem with one of them. My problematic entity is called Invoice and it has many attributes, including Products. It's encoded NSArray of NSDictionaries (via default NSValueTransformer).

Everything works fine - i create my invoice, its client, its products, etc. Everything works.

But, when I choose my invoice from a list and then try to edit its products and click 'Save' button, my save works only until my app gets terminated.

The problem is only with my products array - the rest (e.g. payment date, client etc.) saves.

---

What am I doing

I pass my Invoice object via

NSManagedObject *inv = [self.fetchedResultsController objectAtIndexPath:indexPath];
invoiceEditor.invoice = inv;

And save my data (in my InvoiceEditor VC):

[self.invoice setValue:client forKey:@"Client"] // NSDictionary;
[self.invoice setValue:products forKey:@"Products"] // NSArray of NSDictionaries;
[self.invoice setValue:pmDate forKey:@"PaymentDate"] // NSDate;
// other attributes
NSManagedObjectContext *context = self.invoice.managedObjectContext;
NSError *error = nil;
if (![context save:&error]) {
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}

Everythings saves until being terminated: client, products, dates. But only products are 'reseted' after termination.

Anybody?

解决方案

Just found the problem. From Model Object Implementation Guide:

If there are mutable and immutable versions of a class you use to represent a property—such as NSArray and NSMutableArray—you should typically declare the return value of the get accessor as an immutable object even if internally the model uses a mutable object.

And my products array was actually a NSMutableArray instance. I solved it by copying products (so I converted mutable array to immutable array). Now it works. :) And I didn't need to start the bounty...

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