如何检查记录是否在2个不同的表上？

Question

我正在使用Parse.com并寻找处理此问题的有效方法。

我有一个Sales表，其中包含User引用列和Offer引用列。

销售表跟踪哪些用户进入要约（即10％折扣）。

所以我有以下子类

Offers
Users
Sales

我想显示所有可用的优惠，但设置了一个本地的hasBeenUsed标志，以便我可以以不同的方式显示优惠（如果已经使用过）。

目前我可以创建一个可用优惠的本地数组，但我不确定如何相应地设置这个hasBeenUsed标志。

var query = Message.query()
query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]!, error: NSError!) -> Void in
 for object in objects {
  var offer = Offer()
  offer.info = object["info"] as String
  if (also on the Sales list)
   offer.hasBeenUsed = true
  }
  self.offers.insert(offer, atIndex: 0)
 }
}

Answer 1

警告：请原谅我所犯的任何Swift错误。我仍然只是在Objective-C中写作，我已经尽力写好Swift，但我还不是语法方面的专家。

我能提出的最佳答案是，您需要2个查询（这假设您关注Sales或[PFUser currentUser]的{​​{1}}：

1. 获取当前用户的PFUser.currentUser()个对象列表
2. 获取所有（当前）Sales个对象的列表。

查询1

Swift版本

Offer

Objective-C Version

var query = PFQuery(className:"Sales")
query.includeKey("Offer")
query.whereKey("User", equalTo:PFUser.currentUser())
query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]!, error: NSError!) -> Void in
    if error == nil {
        // Assign the objects to a property or something
        self.sales = objects
        // **Then**, run query 2
        runQuery2()

    } else {
        // Do error handling...
    }
}

查询2

Swift版本

PFQuery *query = [PFQuery queryWithClassName:@"Sales"];
[query includeKey:@"Offer"];
[query whereKey:@"User" equalTo:[PFUser currentUser]];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (error != nil) {
        // Do error handling

    } else {
        // Assign the objects to a property or something...
        self.sales = objects;
        // **Then**, run query 2
        [self runQuery2];

    }
}
 ];

Objective-C Version

var query = PFQuery(className:"Offers")
// Whatever query constraints you need to get "current" offers
query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]!, error: NSError!) -> Void in
    if error == nil {
        // Assign the objects to a property or something
        self.offers = objects;
        // At this point, you have all the data you need, so call the "filter" method
        filter()

    } else {
        // Do error handling...
    }
}

过滤方法

这假设有2个属性：＆＃34; sales＆＃34;，当前用户的销售数组，＆＃34;提供＆＃34;，所有当前优惠的数组

Swift版本

PFQuery *query = [PFQuery queryWithClassName:@"Offers"];
// Whatever query constraints you need to get "current" offers
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (error != nil) {
        // Do error handling

    } else {
        // Assign the objects to a property or something
        self.offers = objects;
        // At this point, you have all the data you need, so call the "filter" method
        [self filter];

    }

}
 ];

Objective-C Version

// First, get all of the "redeemed" offers into an array
var localOffers = [PFObject]()
for sale in self.sales {
    localOffers.append(sale.offer)
    // It might be easier to do it this way
    // localOffers.append(sale.offer.objectId)
}

// Next, iterate the "all offers" array and mark each offer as redeemed/not redeemed
for offer in self.offers {
    if (localOffers.containsObject(offer)) {
    // Alternative check
    // if (localOffers.containsObject(offer.objectId)) {
        offer.hasBeenUsed = true
    } else {
        offer.hasBeenUser = false
    }
}

此时，根据要约是否已兑现，您已获得显示数据所需的内容。请注意不要将// First, get all of the "redeemed" offers into an array NSMutableArray *localOffers = [NSMutableArray array]; for (PFObject *sale in self.sales) { [localOffers addObject:sale.offer]; // It might be easier to do it this way // [localOffers addObject:self.offer.objectId]; } // Next, iterate the "all offers" array and mark each offer as redeemed/not redeemed for (PFObject *offer in self.offers) { if ([localOffers containsObject:offer]) { // Alternative check // if ([localOffers containsObject:offer.objectId]) { offer[@"hasBeenUsed"] = @(YES); } else { offer[@"hasBeenUsed"] = @(NO); } } 值保存到Parse ，除非这是您想要的。