CODEWITHSUNDEEP
firebasegoogle-cloud-firestore
Markus Marvell
Markus Marvell

Reputation: 1916

Query Firebase Firestore documents by the ID

As I got from 'Cloud Firestore Data Model' guide "each document is identified by a name." Is it possible to query a collection by that document identifier (which is the name or ID)?

For example, documents in the collection "Things" have IDs: 0, 1, 2 etc.:

enter image description here

Is it possible to query documents which IDs are less than 100?

Upvotes: 25

Views: 26659

Answers (3)

Carlo Nyte
Carlo Nyte

Reputation: 766

I was struggling to find this for the Golang Firebase SDK but finally got it. Hope this helps somebody out there!

package main
    
import (
  "context"
  "fmt"
  "log"

  "cloud.google.com/go/firestore"
  firebase "firebase.google.com/go/v4"
  "google.golang.org/api/option"
)

type (
  Car struct {
    ID    string
    Name  string  `firestore:"name"`
    Make  string  `firestore:"make"`
    Price float64 `firestore:"make"`
  }
)

func main() {
  ctx := context.Background()

  // Use a service account
  options := option.WithCredentialsFile("PATH/TO/SERVICE/FILE.json")

  // Set project id
  conf := &firebase.Config{ProjectID: "PROJECT_NAME"}

  // Initialize app
  app, err := firebase.NewApp(ctx, conf, options)
  if err != nil {
    log.Fatal(err)
  }

  // Get firestore client
  client, err := app.Firestore(ctx)
  if err != nil {
    log.Fatal(err)
  }
  defer client.Close()

  collectionRef := client.Collection("CAR_COLLECTION")
  
  // Create docment list of documents from "CAR_COLLECTION"
  var skipDocs []*firestore.DocumentRef
  idList := []string{"001", "002", "003"}
  for _, id := range idList {
    skipDocs = append(skipDocs, collectionRef.Doc(id))
  }

  // firestore.DocumentID == "__name__" 
  docs, err := collectionRef.Where(firestore.DocumentID, "not-in", skipDocs).Documents(ctx).GetAll()
  if err != nil {
    log.Fatal(err)
  }

  var carList []Car
  for _, doc := range docs {
    var car Car

    // Unmarshall item
    doc.DataTo(&car)
    car.ID = doc.Ref.ID

    // Add car to list
    carList = append(carList, car)
  }

  // Print car list
  fmt.Println(carList)
}

Upvotes: 1

sillo01
sillo01

Reputation: 614

In python, you should use full documents names

from google.cloud import firestore
from google.cloud.firestore_v1.field_path import FieldPath

db = firestore.Client()
colRef = db.collection(u'docs')
filter = [db.document(u'docs/doc1'), db.collection(u'docs/doc3')]
query = colRef.where(FieldPath.document_id(), u'in', filter)

Upvotes: 18

Michael Lehenbauer
Michael Lehenbauer

Reputation: 16309

You can query by documentId using the special sentinel FieldPath.documentId(), e.g.:

const querySnap = collection.where(firebase.firestore.FieldPath.documentId(), '<', '100').get();

But be aware that document IDs are strings and therefore this will include documents with ID '0' or '1', but not '2' since '2' > '100' lexicographically.

So if you want a numeric query, you'll need to write the document ID as a numeric field in the document and then do a normal query on it.

Upvotes: 45

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