iOS解析如何从基于两个类的查询中检索对象? [英] IOS Parse how do I retrieving objects from a query based on two classes?
问题描述
我有两个类User
和Post
. User
类有一个userType
字段,我想从给定的userType
中检索所有帖子,让我们将它们称为组x.在Post
类中,我有一个指向User
类的指针.
I have two classes User
and Post
. The User
class has a userType
field and I want to retrieve all of the posts from a given userType
lets call them group x. In the Post
class I have a pointer to the User
class.
我试图做类似的事情,首先检索我想要的用户类型的所有用户ID:
I was trying to do something like, first retrieve all user Ids for the type of user I want:
PFQuery *queryUser = [PFQuery queryWithClassName:kFTUserClassKey];
[queryUser whereKey:kFTUserTypeKey equalTo:kFTUserTypeX];
[queryUser whereKey:kFTUserLocationKey nearGeoPoint:nearGeoPoint withinMiles:miles];
[queryUser findObjectsInBackgroundWithBlock:^(NSArray *usersTypeX, NSError *error) {
if (!error) {
NSMutableArray *objectIds = [[NSMutableArray alloc] init];
// Add ambassador ids into query
for (PFObject *userX in usersTypeX) {
[objectIds addObject:[PFObject objectWithoutDataWithClassName:kFTUserClassName objectId: userX.objectId]];
}
}
}];
然后我想基于这些objectIds进行查询,但是我不确定如何在此数组上进行查询,或者这是否是执行此操作的正确方法.该怎么办?
And then I wanted to query based on these objectIds but I am not sure how to query on this array or if this is even the correct way to do this. How can this be done?
推荐答案
Parse在查询中提供了matchesQuery
方法,因此...
Parse provides a matchesQuery
method on query, so ...
PFQuery *innerQuery = [PFQuery queryWithClassName:@"User"];
[innerQuery whereKey:@"userType" equalTo:@"X"]; // fix with your real user type
PFQuery *query = [PFQuery queryWithClassName:@"Post"];
[query whereKey:@"user" matchesQuery:innerQuery];
[query findObjectsInBackgroundWithBlock:^(NSArray *posts, NSError *error) {
// posts are posts where post.user.userType == X
}];
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