I have a collection of "quizes" that users will participate in. When a user takes a quiz I create a document in "results" collection for with that userId and quizId. I want my app to pull all docs from "quizes" collection excluding the ones that the user taken. In SQL I would do "NOT IN" clause and accomplish that, but I have no idea how to best approach this in Firestore.
There's no equivalent query in Firestore. You would need to pull all the data and determine which docs are relevant on clientside.
Alternatively, you can create a list of all quizzes for each user and maintain this list. You could add and remove quizzes for each user as they become relevant/irrelevant to show them.
Related
I'm currently working on an application where users can create groups and invite others in it.
I would like people in the same group to be able to see their first and last names.
To do that, I have a collection named Users where each of the users have a document contains all their personnal data, like first and last names, phone, position , ...
I have also another collection named Groups, where all of my groups are stored, with their name, and an array contaning the ID of the members.
When an user open the app, a first request is done for request his groups (he recieve the groups names and the arrays of members). After, if he want to know the user in a certain group, another request is done for search only the first and last name of all the members.
So, I imagine that there is a query that will return me only the fields that I would like to retrieve, and that there is a rule allowing a potential hacker to be refused access to the entire user document except if the user is the owner of the document.
// For retrieving my user's groups
Stream<List<Group>?> get organizations {
return firestore
.collection('Groups')
.where('members', arrayContains: this.uid)
.snapshots()
.map(_groupsFromSnapshot);
}
// For retrieving names of the members of a group
Stream<List<Member>?> getMembers(Group group){
return firestore
.collection('Users')
// and i dont know what to do here ...
}
With the Client SDKs and the Flutter plugin it is not possible to get only a subset of the fields of a Document. When you fetch a Document you get it with all its fields.
If you want to get only a subset of the fields of a document, you can implements the two following approaches:
Denormalize your data: You create another collection which contains documents that only contain the fields you want to expose. You need to synchronize the two collections (the Users collection, which is the "master", and the new collection): for that it's quite common to use a Cloud Function. Note also that it's a good idea to use the same documentID for the linked documents in the two collections.
Use the Firestore REST API to fetch the data: With the REST API you can use a DocumentMask when you fetch one document with the get method or a Projection when you query a Collection. The DocumentMask or the Projection will "restrict a get operation on a document to a subset of its fields". You can use the http package for calling the API from your Flutter app.
HOWEVER, the second approach is not valid if you want to protect the other users data: a malicious user could call the Firestore REST API with the same request but without a DocumentMask or a Projection. In other words, this approach is interesting if you just want to minimize the network traffic, not if you want to keep secret certain fields of a document.
So, for your specific use case, you need to go for the first solution.
i am building a small web app with MERN, i have a collection that holds "name, email, password, avatar url, and date" and i am going to add to the users some info like a "bio, hobbies(array), "visited countries(array), and another array"
question is, should i create a diffrent model for the users info, and add owner field that refers to the other model?. or should i put all of them there,
also i might add the following and followers option in the future.
The user's info should be in the user collection, I could see there is no reason to have a separate collection for it. If you want to reduce the responses from listing users, you could use populate to remove unnecessary fields.
Regards to the following and followers, I think there are 2 approaches:
Adding a new field which used to store id and necessary metadata (name, avatar) of users to the existing collection
Create a new collection which is a combination of users and users they are following, or are followed. You then could use Virtual to get this information from the User collection.
Personally, I prefer the first approach although it requires more effort to maintain the list to be accurate. E.g remove an item out of the list when your follower stops following you.
I'm using Zapier to look up user information in FireStore based on the user's email address. I have a Top Collection called "groups" which contain users. If I use the attached query in Zapier and hard code the {GROUP_ID}, so that the path is "groups/{GROUP_ID}/users", then the query works.
Successful Zapier Structured Firestore Query
However, I won't know the GROUP_ID at the time of the query. I'm thinking I'll need to loop through all groups (since google's collection groups don't appear to be supported in Zapier). But in order to loop through the groups, I first need to get a list of all the GROUP_ID's.
Because the GROUP_ID's are the top level sub-collection, I can't seem to figure out how to get Zapier to return a list of all of them. Zapier requires that I specify a collection group (groups) and a field path, and cannot leave either blank.
Any help is much appreciated! Thanks!
I have a set of static and pre-defined to-do's that each user in my app needs to be able to set as completed on their account.
At the moment, I use a map on the todo item that specifies which users has completed the task. My data model at the moment looks like this:
- todos (collection)
- todoA (document)
- title, description etc
- completedBy {
uid1: true,
uid2: true,
uid3: false
}
This allows me to easily set todos as completed/not completed for each user and I can easily filter/query. It does have two drawbacks though:
A single Firestore document can "only" have 20 000 properties. If my app would grow large, this would be an issue.
Document size
I was thinking of maybe creating a similar map on my user document instead, setting todo ID's as true/false. This would get rid of the two drawbacks above but I'd need two database queries whenever I'm getting my todo items, one for the todo and one to check if it's completed.
Is there a better way to achieve the desired functionality in Firestore?
If you are running into either the maximum number of fields or the maximum document size, then typically that means that you should be using a separate collection for "the thing that makes your documents so big".
In your case that'd mean that you store the "user has completed a task" in a separate collection. This can be a subcollection of the user document, a subcollection of the task document, and/or a separate top-level collection. Which one is correct depends on your use-case.
There is no single best data model in NoSQL databases. It all depends on your use-cases, trade-offs, and some personal preferences. For a great introduction read NoSQL data modeling and watch Get to Know Cloud Firestore.
Is it possible to "join" indices in Algolia to get a merged result?
For example:
If I have two indices : one for 'users', and one for 'events'. Users each have id and name attributes. Events each have date and userId attributes.
How would I go about searching for all users named "bob", and for each user also return the next 5 events associated with them?
Is it possible to "join" them like you would in a relational database? Or do I need to search for users, then iterate through the hits, searching for events for each user? What's the best solution for this type of query here?
Algolia is not designed as a relational database. To get to what you're trying to achieve, you have to transform all your records into "flat" objects (meaning, each object also includes all their linked dependencies).
In your case, what I would do is to add a new key to your user records, named events and have it be an array of events (just like you save them in the events table). This way, you got all the information needed in one call.
Hope that helps,