In my app to check for if an email (and username) is taken when signing up I use queries like this...
let emailRef = Firebase(url: "https://photocliq5622144.firebaseio.com/users")
emailRef.queryOrderedByChild("email").queryEqualToValue(email.text!.lowercaseString).observeEventType(.Value, withBlock: { email in
Would this work well with hundreds or even thousands of users (is this scalable)?
Hundreds: yes
Thousands: yes
Tens of thousands... probably (and congratulations on the success of your app)
Hundreds of thousands... you're likely better off with a non query-based data model. For example: if you want to access some data for the user by their email address, store a map from email address to uid:
emailToUid
"HelixProbe#stackoverflow,com": "uid6479958"
"puf#stackoverflow.com": "uid209103"
With such a simple list, you can read the user's data from their email address with two direct lookups, instead of one query (which will get slower as more and more items are added).
Scalable or not is determined by your user.
Behind the scene Firebase library is just downloading JSON string and you know exactly what happen if the string is too long and the file size to be downloaded reach (for example 3MByte)
If your user is able and okay with 3MByte for a request, than you can go with it. But I don't if I am your user.
Related
I am creating a Social app and want to track if a username already exists or not. The username list is supposed to grow in future and the way I was doing it now was a key value pair of <string,bolean> like this:
name1: true,
name2: true
all the above data was to be stored in a single document and whenever I want to see if a user exists I would call this document and check accordingly. But here's the problem, firebase max document size is 1MBs and as the users grow this can be problematic, so wanted to know from firebase experts that what's the best way to solve this use case in firestore or realtime database but since I need to query exists maybe realtime db won't suit that well.
Note that I don't want any of firestore querying capabilities but only to check if an entry exists in the record or not and if not just add it.
The Realtime Database doesn't have a 1MB limit (since it has no concept of a document, and everything is just a tree of JSON), so I'd typically use that for the index of user names.
Checking whether a name exists is pretty simple there too, and in JavaScript would look something like:
const usernames = firebase.database().ref('usernames');
usernames.child('name1').once((snapshot) => {
if (snapshot.exists()) {
...
}
});
I’ve seen all around the documentation that Query-based sync is deprecated, so I’m wondering how should I got about my situation:
In my app (using Realm Cloud), I have a list of User objects with some information about each user, like their username. Upon user login (using Firebase), I need to check the whole User database to see if their username is unique. If I make this common realm using Full Sync, then all the users would synchronize and cache the whole database for each change right? How can I prevent that, if I only want the users to get a list of other users’ information at a certain point, without caching or re-synchronizing anything?
I know it's a possible duplicate of this question, but things have probably changed in four years.
The new MongoDB Realm gives you access to server level functions. This feature would allow you to query the list of existing users (for example) for a specific user name and return true if found or false if not (there are other options as well).
Check out the Functions documentation and there are some examples of how to call it from macOS/iOS in the Call a function section
I don't know the use case or what your objects look like but an example function to calculate a sum would like something like this. This sums the first two elements in the array and returns their result;
your_realm_app.functions.sum([1, 2]) { sum, error in
if let err = error {
print(err.localizedDescription)
return
}
if case let .double(x) = result {
print(x)
}
}
What would be the best way to uniquely identify an MSConversation when developing an iMessages application?
In my case I want to give to a game object an ID of the conversation where it belongs to.
Take the localParticipant ID, add to it the remoteParticipants ID ;)
Something like that :
var conversationID = yourConversation.localParticipantIdentifier
for participant in yourConversation.remoteParticipantIdentifiers {
conversationID += participant
}
EDIT:
As noticed in comments, by doing so, you could end up with a very long ID. So the idea is to apply an hash to it, to have a constant size (MD5 is suffisant, we don't need something secure here). If it is still too long, you could crop that hash, but be aware that in that case there is a small probability for two conversations to have the same ID (depending on how much your crop).
The current top answer has a corruption issue in that if a new person is added to a group chat (or if someone is removed) your hashed ID will change.
A more elegant solution in my opinion is to just create your own serial number at the time of the first message being created and add it as meta-data to your message itself. (Using NSURLComponents of course). Then just grab that anytime a message is opened (thus launching your message app) and use that ID. Just keep it in the header of any message sent/received.
But, it depends on what you are trying to do really. The solution I've provided is great for turn-based multi-player games. It might not be good for other scenarios.
I am building an application that I will need to distinguish the Google Contacts from each other. I am just wondering, as long as google sends contacts as First Name/Last Name/mail.. etc (Example) without a unique ID, what will be the first approach to distinguish each contacts?
1) Should I create an ID based on the user's fields? -> by a minimal change, it can break down.
2) Should I create an ID based on First Name + Last Name? -> but most people can have duplicate contacts on their page, would that be a problem? Or married contacts, which can create a little mess.
The reason I am asking this I am trying to create relations and I need to store the data somewhere like that [person=Darth Vader, subject=Luke Skywalker, type=father(or son)], so I need a fast algorithm that can make a mapping for each contact and retrieve the related contacts fast.
I believe they do send back an ID. From the return schema:
<link rel='self' type='application/atom+xml' href='https://www.google.com/m8/feeds/contacts/userEmail/full/contactId'/>
You could use the full HREF value as the ID, or parse out the contactID from the end of the URL, whichever you like better.
I have an MVC2-site using Windows authentication.
When the user requests a page I pull some user information from the database. The class I retrieve is a Person class.
How can get this from the database when the user enters the site, and pick up the same class without touching the db on all subsequent page requests?
I must admit, I am pretty lost when it comes to session handling in ASP.net MVC.
You can store that kind of information in HttpContextBase.Session.
One option is to retrieve the Person object from your database on the first hit and store it in System.Web.HttpContext.Current.Cache, this will allow extremely fast access and your Person data will be temporarily stored in RAM on the web server.
But be careful: If you are storing significantly large amount of user data in this way, you could eat up a lot of memory. Nevertheless, this will be perfectly fine if you only need to cache a few thousand or so. Clearly, it depends upon how many users you expect to be using your app.
You could add like this:
private void CachePersonData (Person data, string storageKey)
{
if (HttpContext.Current.Cache[storageKey] == null)
{
HttpContext.Current.Cache.Add(storageKey,
data,
null,
Cache.NoAbsoluteExpiration,
TimeSpan.FromDays(1),
CacheItemPriority.High,
null);
}
}
... and retrieve like this:
// Grab data from the cache
Person p = HttpContext.Current.Cache[storageKey];
Don't forget that the object returned from the cache could be null, so you should check for this and load from the database as necessary (then cache).
First of all, if you are using a load balanced environment, I wouldn't recommend any solution that you try without storing it in a database, because it will eventually fail.
If you are not in a load balancing environment, you can use TempData to store your object and then retrieve it in the subsequent request.
HttpContext.Current.Session[key];