See the sample code below - in this case, the objectId for the record I am trying to retrieve is known.
My question is, if I don't know the Parse.com objectId, how would I implement the code below?
var Artwork = Parse.Object.extend("Artwork");
var query = new Parse.Query(Artwork);
query.get(objectId, {
success: function(artwork) {
// The object was retrieved successfully.
// do something with it
},
error: function(object, error) {
// The object was not retrieved successfully.
// warn the user
}
});
Query.get() is used when you already know the Parse object id.
Otherwise, one can use query.find() to get objects based on the query parameters.
Sure, you can use Parse Query to search for objects based on their properties.
The thing that wasn't clear to me in the documentation is that once you get the object in the query, you would need to do:
With Query (can return multiple objects):
artwork[0].get('someField');
With 'first' or 'get':
artwork.get('someField');
You cannot do something like artwork.someField like I assumed you would
Related
I've looking for an answer for like 5 five hours straight, hope somebody can help. I have a MongoDb collection results (I'm using mLab) which looks like this:
{
"user":"5818be9c74aaec1824c28626"
"results":[{
"game_id":14578,
"level1":-1,
"level2":-1,
"level3":-1
},
{ ....
}],
{ "user":....
}
}
"user" is a MongoID I save in a previous part of the code, "results" is a record of scores. When an user does a new score, I have to update the score of the corresponding level (I'm using NodeJS).
This is one of the things I've tried so far.
app.get('/levelCompleted/:id/:time', function (request, response) {
var id = request.params.id;
var time = parseInt(request.params.time);
var u= game.getUserById(id);
var k = "results.$.level"+(u.level);
//I build the key to update dinamycally
dbM.collection("results").update(
{user:id,
"results.game_id":u.game_id
//u has its own game_id
},
{$set: {k:time}}
);
...
response.send(...);
});
I've checked the content of every variable and parameter, tried also using $elemMatch and dot notation, set upsert and multi, with no results. I've used an identical command on mongo shell and it has work on the first try.
Update with Mongo Shell
If someone could tell me what I'm doing wrong or point me in the right direction, it would be great.
Thanks
When you use a MongoId as a field in a MongoDB, you can't just pass a string with the id to do the query, you have to identify that string as an ObjectId (Id type in Mongo). Just add a new require in your node.js file.
var ObjectID = require("mongodb").ObjectID;
And use the imported constructor in your update request.
dbM.collection("results").update(
{user:ObjectID(id),...
...
}
Currently, I have a table named Appointments- on appointments, I have a Relation of Clients.
In searching the parse documentation, I haven't found a ton of help on how to eagerly fetch all of the child collection of Clients when retrieving the Appointments. I have attempted a standard query, which looked like this:
var Appointment = Parse.Object.extend("Appointment");
var query = new Parse.Query(Appointment);
query.equalTo("User",Parse.User.current());
query.include('Rate'); // a pointer object
query.find().then(function(appointments){
let appointmentItems =[];
for(var i=0; i < appointments.length;i++){
var appt = appointments[i];
var clientRelation = appt.relation('Client');
clientRelation.query().find().then(function(clients){
appointmentItems.push(
{
objectId: appt.id,
startDate : appt.get("Start"),
endDate: appt.get("End"),
clients: clients, //should be a Parse object collection
rate : appt.get("Rate"),
type: appt.get("Type"),
notes : appt.get("Notes"),
scheduledDate: appt.get("ScheduledDate"),
confirmed:appt.get("Confirmed"),
parseAppointment:appt
}
);//add to appointmentitems
}); //query.find
}
});
This does not return a correct Clients collection-
I then switched over to attempt to do this in cloud code- as I was assuming the issue was on my side for whatever reason, I thought I'd create a function that did the same thing, only on their server to reduce the amount of network calls.
Here is what that function was defined as:
Parse.Cloud.define("GetAllAppointmentsWithClients",function(request,response){
var Appointment = Parse.Object.extend("Appointment");
var query = new Parse.Query(Appointment);
query.equalTo("User", request.user);
query.include('Rate');
query.find().then(function(appointments){
//for each appointment, get all client items
var apptItems = appointments.map(function(appointment){
var ClientRelation = appointment.get("Clients");
console.log(ClientRelation);
return {
objectId: appointment.id,
startDate : appointment.get("Start"),
endDate: appointment.get("End"),
clients: ClientRelation.query().find(),
rate : appointment.get("Rate"),
type: appointment.get("Type"),
notes : appointment.get("Notes"),
scheduledDate: appointment.get("ScheduledDate"),
confirmed:appointment.get("Confirmed"),
parseAppointment:appointment
};
});
console.log('apptItems Count is ' + apptItems.length);
response.success(apptItems);
})
});
and the resulting "Clients" returned look nothing like the actual object class:
clients: {_rejected: false, _rejectedCallbacks: [], _resolved: false, _resolvedCallbacks: []}
When I browse the data, I see the related objects just fine. The fact that Parse cannot eagerly fetch relational queries within the same call seems a bit odd coming from other data providers, but at this point I'd take the overhead of additional calls if the data was retrieved properly.
Any help would be beneficial, thank you.
Well, in your Cloud code example - ClientRelation.query().find() will return a Parse.Promise. So the output clients: {_rejected: false, _rejectedCallbacks: [], _resolved: false, _resolvedCallbacks: []} makes sense - that's what a promise looks like in console. The ClientRelation.query().find() will be an async call so your response.success(apptItems) is going to be happen before you're done anyway.
Your first example as far as I can see looks good though. What do you see as your clients response if you just output it like the following? Are you sure you're getting an array of Parse.Objects? Are you getting an empty []? (Meaning, do the objects with client relations you're querying actually have clients added?)
clientRelation.query().find().then(function(clients){
console.log(clients); // Check what you're actually getting here.
});
Also, one more helpful thing. Are you going to have more than 100 clients in any given appointment object? Parse.Relation is really meant for very large related collection of other objects. If you know that your appointments aren't going to have more than 100 (rule of thumb) related objects - a much easier way of doing this is to store your client objects in an Array within your Appointment objects.
With a Parse.Relation, you can't get around having to make that second query to get that related collection (client or cloud). But with a datatype Array you could do the following.
var query = new Parse.Query(Appointment);
query.equalTo("User", request.user);
query.include('Rate');
query.include('Clients'); // Assumes Client column is now an Array of Client Parse.Objects
query.find().then(function(appointments){
// You'll find Client Parse.Objects already nested and provided for you in the appointments.
console.log(appointments[0].get('Clients'));
});
I ended up solving this using "Promises in Series"
the final code looked something like this:
var Appointment = Parse.Object.extend("Appointment");
var query = new Parse.Query(Appointment);
query.equalTo("User",Parse.User.current());
query.include('Rate');
var appointmentItems = [];
query.find().then(function(appointments){
var promise = Parse.Promise.as();
_.each(appointments,function(appointment){
promise = promise.then(function(){
var clientRelation = appointment.relation('Clients');
return clientRelation.query().find().then(function(clients){
appointmentItems.push(
{
//...object details
}
);
})
});
});
return promise;
}).then(function(result){
// return/use appointmentItems with the sub-collection of clients that were fetched within the subquery.
});
You can apparently do this in parallel, but that was really not needed for me, as the query I'm using seems to return instantaniously. I got rid of the cloud code- as it didnt seem to provide any performance boost. I will say, the fact that you cannot debug cloud code seems truly limiting and I wasted a bit of time waiting for console.log statements to show themselves on the log of the cloud code panel- overall the Parse.Promise object was the key to getting this to work properly.
I am trying to get all of the users that are following the current user. From some reason Parse returns the username as undefined in the 'to' field but I am able to retrieve the user name from the 'from' field like so:
var query = new Parse.Query("Follow");
query.equalTo("to", Parse.User.current());
query.find({
success: function(users){
for (var i = 0; i < users.length; i++) {
console.log(users[i].get('from').get('username')) // returns current username
console.log(users[i].get('to').get('username')) / returns undefined
}
}
});
But those values do exist and there is a username. I am able to get the value using the fetch method but I am curious as to why this approach doesn't work. Thoughts?
From Doc, you're not getting the actual object, but the ref to that object:
Internally, the Parse framework will store the referred-to object in just one place, to maintain consistency. ......
And
By default, when fetching an object, related Parse.Objects are not
fetched. These objects' values cannot be retrieved until they have
been fetched like so:
// Here, post is something similar to your `users[i].get('to')`
var post = fetchedComment.get("parent");
// So you need to fetch it again to get its real object.
post.fetch({
success: function(post) {
var title = post.get("title");
}
});
So what you get from users[i].get('to') is a reference to that user object. You can either fetch it again.
I have a REST API serving a few URLs:
/rest/messages
provides all messages. A message is a JSON/Backbone Model
{
title: 'foo',
body : 'bar'
}
To get a single message I have:
/rest/messages/:id
Is it possible to fetch a Backbone Collection using message IDs array? I don't want the whole message list, but just a few messages I specify by ID.
I could fetch Models one-by-one and fill up the Collection, but I'm wondering if Backbone has a cleaner way to do this.
Thanks
According to documentation, you can pass ajax options to the fetch call. So, you can pass ids as data attribute to the fetch call being done and based on it, return the respective models from the server.
For example (when doing fetch),
collection.fetch({
data : {
message_ids : [1, 3, 5] // array of the message ids you want to retrieve as models
}
})
This message_id array will be accessible as parameters (not sure of the name in your case) in the server code being executed at /rest/messages, from there you can return only specific models based on ids you receive as message_ids. The only thing you need is, client side must be aware of the ids of all the message models it needs.
You can use any data structure instead of array to send message_ids.
The url property of collection reference to the collection location on the server. When you use fetch, backbone uses that url.
The url property can be also a function that returns the url. So you can do something like that:
var ids = [1,2,3]
var messages = new MessegecCollection();
messages.url = function() {
return "/rest/messages/"+ids.join("-"); //results "/rest/messages/1-2-3"
}
messages.fetch();
You can also create a method in your collection that generated and set the url, or even fetchs a set of models.
Now all you have to do is to support this url: /rest/messages/1-2-3
Hope this helps!
In my app, everything I do with data is based on the primary key as the data is stored in the database. I would like to grab a model from a collection based on this key.
Using Collection.at() requires the array index, Collection.getByCid() requires the client ID that backbone randomly generates.
What is the best way to grab the model I want from the collection with the given id value? I figure the worst I could do would be to iterate over each item, .get('id'), and return that one.
Take a look at the get method, it may be of some help :)
http://backbonejs.org/#Collection-get
get collection.get(id)
Get a model from a collection, specified by an id, a cid, or by passing in a model.
If your data requires you to use a different kind of key or a set that doesn't mesh well with at(), getByCid() or get(), there is also where(). Something like this might work:
window.lib = new Library;
window.lib.fetch([
success: function(model, response) {
console.log(window.lib.where({'BookID':488, 'Rev':2, 'Status':'Active'});
}
});