Parse PFQuery Predicate Pointer Object

Question

I am performing a simple PFQuery to fetch a bunch of Box objects (class name).

My Box has a pointer to a Toy object called toy.

I let my user select a bunch a toys, then the search only display the Box objects with those Toy objects.

So I end up with an NSArray of PFObjects of type Toy. I have an array of objectId strings for the objects, and I just create another array like this:

PFObject *obj = [PFObject objectWithoutDataWithClassName:@"Toy" objectId:objectId];

Now I can query the object, I would have thought. I have tried doing a query of Box objects with an NSPredicate which looks like this:

[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"toy = %@", toyObject]];

My app crashes and tells me it is unable to parse that. So before adding the predicate I take the objectId instead and try doing that:

[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"toy.objectId = %@", toyObject.objectId]];

However, it doesn't like that format either. So how can I create an NSPredicate that lets me only fetch objects with a specific pointer result like explained.

poopit · Accepted Answer · 2015-09-03 19:22:00Z

2

In other words just use

 PFUser *user = [PFUser currentUser];
 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"fromUser = %@", user];

where in this example, "user" is a pointer stored in the table and we're searching for it under the "fromUser" column

answered Sep 3, 2015 at 19:22

poopit

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mbm29414 · Accepted Answer · 2015-01-10 20:46:45Z

1

I think you're making this too hard on yourself. If I'm reading your question correctly, there is a much simpler way to do this, and you don't have to use NSPredicate at all:

NSMutableArray *toys = [NSMutableArray array];
// Figure out some way (during selection) to get the "toy" objects into the array
PFQuery *query = [PFQuery queryWithClassName:@"Box"];
[query whereKey:@"toy" containedIn:toys];
[query findObjects... // You should know the rest here

And that's it! Nice and easy, should find all Box instances that have a toy that is contained in the toys array.

answered Jan 10, 2015 at 20:46

mbm29414

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3 Comments

Josh Kahane Over a year ago

Thanks for the answer, I probably was over complicating, but I found the answer! While your method works, I need to use an NSPredicate, and the reason it couldn't parse the format was because I was using stringWithFormat, which screws up NSPredicates.

mbm29414 Over a year ago

For your stated problem, you don't need to use NSPredicate. What other information makes you think you do?

Josh Kahane Over a year ago

Sorry I didn't specify, I was trying to keep the question as simple as possible. I don't need per-say but it is easier in my scenario as I need to pass it around bunch and command among other things. Thats why I said I wanted to achieve this using an NSPredicate.

Josh Kahane · Accepted Answer · 2015-01-10 21:35:38Z

0

Turns out it was pretty simple.

Don't use [NSString stringWithFormat:(NSString *)] if you are creating an NSPredicate format string. NSPredicate really doesn't like it and can often fail to parse your format.

answered Jan 10, 2015 at 21:35

Josh Kahane

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