任何人都知道如何在 QueryForTable 中缩小这个查询（使用 Parse.com）

Posted 2023-03-08

【中文标题】任何人都知道如何在 QueryForTable 中缩小这个查询（使用 Parse.com）

【英文标题】：Anyone know how to shrink this query in QueryForTable (using Parse.com)

【发布时间】：2012-12-20 10:14:49

【问题描述】：

有人知道如何缩小这个，这样我就不必在 QueryForTable 方法的主线程中运行查询了吗？我正在使用 Parse.com

//Find who are the users following (RELATIONSHIP OBJECT)
PFQuery *followeesQuery = [PFQuery queryWithClassName:@"Relationship"];
[followeesQuery whereKey:@"Follower" equalTo:[PFUser currentUser]];
NSArray *followees = [followeesQuery findObjects];
//Filter followees
self.followees = [[NSMutableArray alloc] initWithCapacity:[followees count]];
for (int i = 0; i < [followees count]; i++) 
    PFObject *followee = followees[i];
    PFUser *user = (PFUser *)[followee objectForKey:@"User"]; //USER OBJECT
    [self.followees addObject:user];



PFQuery *nearbyPhotosQuery = [PFQuery queryWithClassName:@"Photo"]; //PHOTO OBJECT
[nearbyPhotosQuery whereKey:@"User" notContainedIn:self.followees];
[nearbyPhotosQuery whereKey:@"Location" nearGeoPoint:self.userCurrentLocation withinKilometers:10];

PFQuery *followersPhotoQuery = [PFQuery queryWithClassName:@"Photo"]; //PHOTO OBJECT
[followersPhotoQuery whereKey:@"User" containedIn:self.followees];

NSMutableSet *set = [NSMutableSet setWithArray:[nearbyPhotosQuery findObjects]];
[set addObjectsFromArray:[followersPhotoQuery findObjects]];

NSArray *targetPhotoObjects = [set allObjects];

NSMutableArray *targetIDs = [[NSMutableArray alloc] initWithCapacity:[targetPhotoObjects count]];
for (int i = 0; i < [targetPhotoObjects count] ; i++) 
    PFObject *photoObject = targetPhotoObjects[i];
    [targetIDs addObject:photoObject.objectId];



PFQuery *targetPhotoQuery = [PFQuery queryWithClassName:@"Photo"];
[targetPhotoQuery whereKey:@"objectId" containedIn:targetIDs];


return targetPhotoQuery;

【参考方案1】：

如果我没看错，您想查询关注者或您附近的所有照片。为什么不使用：

PFQuery *followeesQuery = [PFQuery queryWithClassName:@"Relationship"];
[followeesQuery whereKey:@"Follower" equalTo:PFUser.currentUser];

PFQuery *followeesPhotosQuery = [PFQuery queryWithClassName:@"Photo"];
[followeesPhotosQuery whereKey:@"User" matchesKey:@"User" inQuery:followeesQuery];

PFQuery *nearbyPhotosQuery = [PFQuery queryWithClassName:@"Photo"];
[nearbyPhotosQuery whereKey:@"Location"
               nearGeoPoint:self.userCurrentLocation
            withinKilometers:10];

return [PFQuery orQueryWithSubqueries:@[followeesPhotosQuery, nearbyPhotosQuery]];

这是一个与您要查找的内容相匹配的查询，不需要创建服务器端行程。如果您希望在流程的任何步骤中返回超过 100 个元素，您可能需要使用内部查询返回的最大元素数；一路上的每个查询都受制于自己的查询限制。