解析云代码-承诺

Question

I'm trying to send push notifications to my users via Parse Background Job if they are in proximity of the pet that was created.

Every user in range gets crosschecked with the pets (confirmed via log) but the push notifications are sent to the wrong user or most of the time not even sent at all. I'm pretty sure I messed the promises up but can't the problem here.

Any help would be much appreciated, thanks!

Parse.Cloud.job("locationPush", function(request, status) {

Parse.Cloud.useMasterKey();

var Pet = Parse.Object.extend("Pet");
var petQuery = new Parse.Query(Pet);
petQuery.equalTo("initialPushSent", false);
petQuery.equalTo("status", "missing");
petQuery.equalTo("deleted", false);

petQuery.find().then(function(pets) {
  var petPromises = [];
  _.each(pets, function(pet) {
    console.log("checking pet: " + pet.id);

    var petLocation = pet.get("lastSeenLocation");
    var query = new Parse.Query(Parse.User);
    query.withinKilometers("lastLocation", petLocation, 50);

    query.find().then(function(users) {

        var userPromises = [];

        _.each(users, function(user) {

            var userPromise = new Parse.Promise();
            userPromises.push(userPromise);

            console.log("check user " + user.id + " with pet: " + pet.id);

            var pushPromises = [];

            if(petLocation.kilometersTo(user.get("lastLocation")) <= user.get("pushRadius")){

                console.log("send push to" + user.id);

                var promise = new Parse.Promise();
                pushPromises.push(promise);

                Parse.Push.send({
                    channels: [ "user_" + user.id ],
                    data: {
                        alert : "Neues vermisstes Tier im Umkreis"
                    }}, 
                    { success: function() {
                        console.log("push sent to: " + user.id)
                    }, 
                    error: function(error) {
                        console.log("error sending push: " + error)

                    }}).then (function(result){
                        promise.resolve();
                    }, function(error) {
                        promise.reject();
                    });

                }

                return Parse.Promise.when(pushPromises);


            });


        return Parse.Promise.when(userPromises);

    });

    petPromises.push(pet.save());
  });

  return Parse.Promise.when(petPromises);

}).then(function() {
    status.success("location Send complete"); 

}, function(error) {
    status.error("location Send Error"); 

});

Answer 1

You need to return a promise from really absolutely every function that does something asynchronous. In your case, you dropped the promise that was returned by query.find() , and called pet.save() immediately. I guess you wanted to chain them.

Also, your userPromise s were never resolved, which likely is the reason that your chain failed. And your pushPromises array is quite unnecessary, as it only will contain at most one promise.

Also, I've used _.map instead of pushing to arrays, and removed the deferred antipattern that you had used. It makes the returns more prominent, so that it's easier to spot if you forgot one.

Parse.Cloud.job("locationPush", function(request, status) {
    Parse.Cloud.useMasterKey();
    var Pet = Parse.Object.extend("Pet");
    var petQuery = new Parse.Query(Pet);
    petQuery.equalTo("initialPushSent", false);
    petQuery.equalTo("status", "missing");
    petQuery.equalTo("deleted", false);
    return petQuery.find().then(function(pets) {
        return Parse.Promise.when(_.map(pets, function(pet) {
            console.log("checking pet: " + pet.id);
            var petLocation = pet.get("lastSeenLocation");
            var query = new Parse.Query(Parse.User);
            query.withinKilometers("lastLocation", petLocation, 50);
            query.find().then(function(users) {
                return Parse.Promise.when(_.map(users, function(user) {
                    console.log("check user " + user.id + " with pet: " + pet.id);

                    if (petLocation.kilometersTo(user.get("lastLocation")) <= user.get("pushRadius")) {
                        console.log("send push to" + user.id);
                        return Parse.Push.send({
                            channels: ["user_" + user.id],
                            data: {
                                alert: "Neues vermisstes Tier im Umkreis"
                            }
                        }, {
                            success: function() {
                                console.log("push sent to: " + user.id)
                            },
                            error: function(error) {
                                console.log("error sending push: " + error)
                            }
                        }); // we already got a promise here!
                    } else
                        return null;
                }));
            }).then(function() {
                return pet.save();
            });
        }));
    }).then(function() {
        status.success("location Send complete");
    }, function(error) {
        status.error("location Send Error");
    });
});