How to get array of documentSnapshot from httpsCallable firestore function in JSON format

Question

So I would like to load firestore documents using httpsCallable cloud functions, on my client application. Before I loaded my documents with a typical getDocuments function and it returned an array of simple JSON format snapshots, like so:

Firestore.firestore().collection("users").getDocuments { (snapshot, err) in
if let err = err{
                print("Failed to load data from firebase:", err)
                return
            }
snapshot?.documents.forEach({ (documentSnapshot) in
// documentSnapshot.data() is in JSON format
...
    }
}

And now I would like to load my documents with the return of a httpsCallable cloud function. So I have my cloud function working well and returning my documents' data. But the issue that I'm having is in the return format of the function. The data I receive from the cloud function is in the following format:

(
        {
        index = 34;
        field1 =         (
            "yes",
            "no",
            "maybe"
        );
        field2 = 26;
        brand = Puma;
        color = "marshmallow-natural";
        EcoFriendly = 1;
     },
      {
        index = 12;
        field1 =         (
            "oui",
            "non",
            "peut-être"
        );
        field2 = 21;
        brand = Nike;
        color = "red";
        EcoFriendly = 0;
     }
...
)

I observe this by calling the function as follows:

functions.httpsCallable("smartShoeFinder").call([
        "vector": fireV[0]]) { (result, error) in
          
            if let error = error as NSError? {
            // Handle error
          }
            print(result?.data)
            //The following is my attempt towards extracting the data and
            // converting it to an array of JSON:
            let requestResult = result!.data
            if let swiftArray  = result!.data as! NSArray as? [Any] {
                print(swiftArray[0])
            }
            
  }

I would like my data as an array of JSON as so:

[["index": 34, "field1": ["yes", "no", "maybe"], "field2": 26, "brand": "Puma", "color" = "marshmallow-natural", "shoeEcoFriendly": 1], 
["index": 12, "field1": ["oui", "non", "peut-être"], "field2": 21, "brand": "Nike", "color" = "red", "shoeEcoFriendly": 1]]

Before the format was an array of simple JSON dictionaries (as can be seen above) easily convertable to my different client objects. Now it is a __NSArrayM (which is apparently a NSMutableArray). So do you know if I can get the return of my httpsCallable firestore function in an array of JSON? Just like the following request:

Firestore.firestore().collection("users").getDocuments{ (snapshot, err) in
    snapshot?.documents.forEach({ (documentSnapshot) in
    documentSnapshot.data() // I'd like it in this format
    }
}

My firestore function returns an array of the following data (TypeScript):

const db = admin.firestore();
export const smartShoeFinder = functions.https.onCall(async (data, context) => {
let outputDocuments = new Array()
const collection = await db.collection('collection')
const notVisited = [1,32,13,44,15,26]
for (const index of notVisited){
    console.log(index)
    const snap = await collection.where("index", "==", index).get()
    if (snap.size == 0){
       continue
       }
    const onlyDoc = snap.docs[0].data
    outputDocuments.push(onlyDoc) // Populating the array with the wanted documents
  }
// Now returning promise to the client
.then(() => {
    return new Promise((resolve, reject) => {
        resolve(outputDocuments)
    })
})
.catch(err => console.log(err))
})

where outputDocuments is the array of document data.

Is there a better way to do this?

Please edit the question to show the entire code of the function that isn't working the way you expect, in addition to the client code that invokes it. That three line snippet isn't enough to see what it's doing. There should be enough information in the question so that anyone can reproduce the behavior. — Doug Stevenson, Sep 08 '20 at 15:18
Okay, I added the essence of the function. I really like your firebase videos btw Doug, thank you very much for those! I was just watching the ones on functions this morning! — Antoine Neidecker, Sep 08 '20 at 15:31
What is the client code that invokes this function? How are you observing the results, and how is that different than what you expect? — Doug Stevenson, Sep 08 '20 at 15:32
The client prints a __NSArrayM of data with a non-JSON format. I'm trying to get an Array (any type) with JSON format. — Antoine Neidecker, Sep 08 '20 at 16:19

score 0 · Answer 1 · answered Sep 09 '20 at 08:43

I am a JavaScript developer and have limited knowledge in Swift but you can simplify the code like so:

const db = admin.firestore();

exports.smartShoeFinder = functions.https.onCall(async (data, context) => {
    // FROM CLIENT AS AN ARRAY OF INTEGERS
    const notVisited = data.notVisited;     

    function getDoc(index){
        // RETURNS THE QUERY WHICH IS ALREADY A PROMISE SO NO NEED TO WRAP IT
        return db.collection('collection').where("index", "==", index).get().then(colSS=>{
            if (r.empty){
                return {
                    isEmpty: true
                };
            }
            else{
                return {
                    isEmpty: false,
                    doc: r.docs[0].data()
                };
            }
        }).catch(e=>{
            console.log("QUERY ERROR: " + e.message);
        })
    }
    // STORES ALL QUERIES IN AN ARRAY OF PROMISES
    let processes = notVisited.map(index=>{
        return getDoc(index);
    })
    // USE Promise.all() TO RESOLVE ALL THE PROMISES IN PARALLEL
    return Promise.all(processes).then(result=>{
        // FILTER OUT THE NON EMPTY ONES AND EXTRACT THE DATA.
        return result.filter(query=>{
            return !query.isEmpty;
        }).map(query=>{
            return query.doc;
        })
    })
})

Alternatively, it can be further simplified ONLY IF your array of notVisited indices is within 10 elements long using the array-contains-any query and converting the "index" field to an array of single element (which you need to prepare beforehand for each document) like so:

const db = admin.firestore();

exports.smartShoeFinder = functions.https.onCall(async (req, context) => {
    return await db.collection("collection").where("index", "array-contains-any", data.notVisited).then(colSS=>{
        return colSS.docs.map(docSS=>{
            return docSS.data();
        })
    })
})

How to get array of documentSnapshot from httpsCallable firestore function in JSON format

1 Answers1