Query on variable of nested object

[vdkdamian]

Back with another question.

I know it's possible to query relations. But I think I need something different.
I have a Pointer and I should need to be able to query all objects where a variable of that pointer is some specified value.

Eg.:

public struct Product: ParseObject {
    public var objectId: String?
    public var createdAt: Date?
    public var updatedAt: Date?
    public var ACL: ParseACL?
    public var originalData: Data?
    
    public var name: String?
    public var category: Category?
}

public struct Category: ParseObject {
    public var objectId: String?
    public var createdAt: Date?
    public var updatedAt: Date?
    public var ACL: ParseACL?
    public var originalData: Data?
    
    public var name: String?
}

I would need all Products where the name of Category for example == "Clothes".
I don't know if this is possible and how to do it.

Was thinking of something like this:

let productQuery = Product.query("category.name" == "Clothes")
        let products = try await productQuery.findAll()

[cbaker6]

This would be up to the server, not the Swift SDK. You would need to ask this question there to see if they allow such a query.

[cbaker6]

I'll note, I don't think a query like you are asking for needs to be supported on the server, you can achieve the same thing by using the correct combinations of QueryContraint, for example, matchesKeyInQuery, doesNotMatchKeyInQuery, and, or, nor, etc. You can see all of the possible QueryConstraint's by looking at the Functions section of the documentation

[vdkdamian]

I'll take a look at it!

[vdkdamian]

Do you have some examples of use cases?
I find it hard to see what it does.

[cbaker6]

You can search for matchesKeyInQuery in the JS guide or the matchesKey Objective-C guide. You can almost always find an equivalent in the JS guides

[jaysonng]

@vdkdamian check the inQuery section of ParseQueryTests.swift

Basically I think what you need is to just get your Category object first and match that to the Product object

let inQuery = Category.query("name" == "Clothes")
let query = Product.query("category" == inQuery)
return try await query.findAll()

I think this code should get you what you need if I understood your original question correctly.

[vdkdamian]

I tried it, but it doesn't seem to work.

[jaysonng]

what's the error?

try placing it in a do-catch

do {
         let inQuery = try Category.query("name" == "Clothes").includeAll()
         let query = Product.query("category" == inQuery).includeAll()
         return try await query.findAll()
     } catch  {
         throw error
     }

[cbaker6]

Your code will probably look something like below (the guides I posted in #32 (reply in thread) further explain why):

let clothesQuery = Category.query("name" == "Clothes")
let productQuery = Product.query(matchesKeyInQuery(key: “category”,
                                                           queryKey: “name”,
                                                           query: clothesQuery))
do {
  let results = try await productQuery.find() // You should only use findAll when necessary is this isn’t an optimal query, you should only request what you need from the server
  print(results)
} catch {
  // Handle error
}

Note that if you don’t find something in the Playgrounds, it’s recommended to look through SnapCat, ParseCareKit and testcases as those are intended to demonstrate how to use the SDK.

[vdkdamian]

To everyone else needing this, try setting the queryKey to "objectId"

[vdkdamian]

Okay, so I was trying a lot of things and kept failing to get it working.
I finally found how it works.
Apparently setting queryKey to "objectId", it worked for me.
Now I am thinking that that seems logically to me and would suggest a change in the code for simpler use.

What do you think if we change this function

public func matchesKeyInQuery <T>(key: String, queryKey: String, query: Query<T>) -> QueryConstraint {
    let select = QuerySelect(query: InQuery(query: query), key: queryKey)
    return QueryConstraint(key: key, value: select, comparator: .select)
}

to this function:

public func matchesKeyInQuery <T>(key: String, queryKey: String = "objectId", query: Query<T>) -> QueryConstraint {
    let select = QuerySelect(query: InQuery(query: query), key: queryKey)
    return QueryConstraint(key: key, value: select, comparator: .select)
}

To me it seems like most people would need the basic use and set the queryKey to "objectId". But let me know what you think!

[vdkdamian]

I was trying examples based on SnapCat, but couldn't get them working.
Could it be it has something to do with the fact that I am using customObjectId's?
Can't think of anything else that's different on my configuration.

[cbaker6]

It seems what you need is a simpler version that shouldn't need matchesKeyInQuery. From what you've listed, @jaysonng's example of using == in #32 (comment) should have worked for you if category really is a ParseObject:

let inQuery = Category.query("name" == "Clothes")
let query = Product.query("category" == inQuery)
do {
  let results = try await query.find()
  print(results)
} catch {
  // Handle error
}

[vdkdamian]

Ah yes, I checked and it's working indeed. Must have done something wrong when trying @jaysonng example.

[jaysonng]

I was wondering why my code didn't work for you as it works fine on my code. I don't have a matchesKeyInQuery in my project (but started looking into it and playing with it since this discussion began).

[vdkdamian]

@jaysonng Think I did something wrong with my first query. But it's working now