CODEWITHSUNDEEP
swiftfirebasegoogle-cloud-firestore
michael-martinez
michael-martinez

Reputation: 797

Managing indexes in Firebase Firestore

I am trying to have custom order to String collection elements in I fetch from Firebase FireStore.

I am quite confused with the documentation with custom indexes and composite indexes. I have several categories lets say Restaurants, Exits, Shops and I simply want them to be ordered the same way in when I fetch them. I want to receive Exits then Restaurants then Shops.

In the admin panel, they are not ordered properly and I would like to reorder them. The client code that fetches data is swift code.

Upvotes: 0

Views: 235

Answers (1)

Dennis Alund
Dennis Alund

Reputation: 3149

Firestore automatically creates single-field indexes for all fields on your documents (read more). That means that simple queries will work straight out of the box.

So a query like this should provide you with the result that you are looking for: any place sorted by categories in alphabetical order. And this works because you are only querying one field.

placesCollectionRef.order(by: "category", descending: false)

But often you want to match one field and sort by another. And in that case you will need a composite index.

placesCollectionRef
  .whereField("state", isEqualTo: "CA")
  .order(by: "category", descending: false)

Firebase is being very helpful in identifying when we need an index. If you do a test run of your app, Firebase will throw an error if there was any query that was missing a necessary index. The error message will contain a URL that links to your Firebase project console and opens a dialog for creating the index.

Upvotes: 2

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