How can i convert my firebase realtime database function to firestore function

Question

I had a working firebase realtime database function that i wrote previously, however as i changed my database from realtime database to firestore it isnt working right now, i converted a bit but i am having problem to figure out how to convert (.then ....) part. What i would like to do is when a users status field changes in its document i want the function to query in the firestore database and look for other ppl's documents whose status field are also waiting and pick one of them randomly, then change its document values as below in the example

Here is a part of the original firebase realtime database function, it is

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.sayi = functions.database.ref("/users/{uid}/status").onWrite((change, context) => {
        console.log("status degisti");
        var rastgele = Math.floor(Math.random() * 2);
        var status = change.after.val();
        var user = change.after.ref.parent.key;  
        if (status ==="waiting") {
            const events = admin.database().ref('users');
            const query =events.orderByChild('status').equalTo('waiting').limitToFirst(2);
            query.on("value",
             function(data) {
                var waitinggameusers = data.val();
                var keys = Object.keys(waitinggameusers);
                for (var i = 0; i < keys.length; i++) {            
                    var key = keys[i];
                    if(key!==user){
                        var updates = {};
                        updates["/users/"+user+"/rakip"] = key;
                        updates["/users/"+key+"/rakip"] = user;
                        updates["/users/"+user+"/rakipsallama"] = "";
                        updates["/users/"+key+"/rakipsallama"] = "";
                        updates["/users/"+user+"/status"] = "on";
                        updates["/users/"+key+"/status"] = "on";
                        updates["/users/"+user+"/turn"] = "off1";
                        updates["/users/"+key+"/turn"] = "off2";                    
                        admin.database().ref().update(updates);
                        return true;
                    }             
                }
            }, sorunlu);
        }
    });

my current firestore version:

    const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
const db = admin.firestore();

exports.yenisayi3 = functions.firestore.document('users/{userId}').onUpdate((change, context) => {
    const newValue = change.after.data();
    const previousValue = change.before.data();
    const userdoc = context.params.userId;
    if (newValue.status ==previousValue.status) {
        console.log("status degismedi");
        return true;
    }else{
        console.log("status degisti");
        var status = newValue.status;
        if(status==="off"||status==="on"||status==="win"){
            return false;
        }
        if (status ==="waiting") {
            return db.collection('users').where('status', '==', 'waiting').get().then(
                result=>{
                    if (result.docs.length === 0) {
                        return false;
                    }else{
                        return result.doc[0].ref.update({
                        status: 'on',
                        });
                    }
            });
        }
    }
});

Currently i am getting

TypeError: Cannot read property '0' of undefined
    at db.collection.where.get.then.result (/srv/index.js:31:24)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)

My database layout is like this:

Hi @Faruk indeed, you can use a `where`, to return the specific values. Could you please take a look at these cases [here](https://stackoverflow.com/questions/54172490/how-to-update-document-in-firebase-cloud-function) and [here](https://stackoverflow.com/questions/58213619/how-to-update-multiple-documents-from-cloud-function-in-firestore-database) and check if they help you? They provide some examples of how to use a Cloud Function to update documents in Firestore. — gso_gabriel, Oct 26 '20 at 14:12
Hi Gabriel, thanks for the page, although it was usefull it didnt fix all of my problems i need to limit result to 1 doc and it should be random, also currently it gives me the faloowing error i posted. — Faruk, Oct 26 '20 at 15:22

score 2 · Accepted Answer · answered Oct 26 '20 at 19:37

2

Instead of return result.doc[0].ref.update() you probably want return result.docs[0].ref.update(). You're missing an 's'.

answered Oct 26 '20 at 19:37

Doug Stevenson

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How can i convert my firebase realtime database function to firestore function

1 Answers1