CODEWITHSUNDEEP
swiftfirebasefirebase-realtime-database
Gal Shahar
Gal Shahar

Reputation: 2795

Firebase Query Under AutoID Under Child Swift

My Firebase Database

Hello! I'm trying to make two Firebase queries:

  1. All children under basicInfo, for multiple users at once (query limited by 20 results). For example, in this query with the above database I will get all basicInfo sections for -Kwz1eoUMPym... and also for -Kwzhj4pzBJxbb...

  2. All children under basic info where name == (some name).

I can't understand how to approach a name query under the AutoID key and also under basicInfo key, for both queries.

What is the most logical approach to this?

Upvotes: 1

Views: 687

Answers (1)

Grimthorr
Grimthorr

Reputation: 6926

The Firebase Realtime Database is a NoSQL database, and it's only possible to filter by direct descendents of children in a list. Therefore, you will need to use a flatter data structure, and avoid splitting your fields into basicInfo, fullInfo:

users
|- userId
   |- name: "John"
   |- age: 17
   |- gender: "m"
   |- birthday: "10.10.2000"
   ...

With this approach, you can attach a listener to the users node and then filter by child values using the queryOrderedByChild and queryEqualToValue methods. For example, something like this in Swift:

Database.database().reference().child("users").queryOrderedByChild("name").queryEqualToValue("(some name)").observeSingleEventOfType(.Value, with: { snap in  
    // Do your thing with snap
})

With either of your structures, you can limit your results with the queryLimitedToFirst and queryLimitedToLast methods. For example, from the filtering data section of the documentation:

The following example demonstrates how example blogging app retrieves a list of the 100 most recent posts by all users:

// Last 100 posts, these are automatically the 100 most recent
// due to sorting by push() keys
let recentPostsQuery = (ref?.child("posts").queryLimited(toFirst: 100))!

For more details on filtering and limiting Firebase data in Swift/iOS, see the working with lists of data on iOS documentation.

Upvotes: 3

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