How do you insert a "reference" value into firestore?

Question

I'm trying to insert a document into a collection. I want the document to have a attribute of type reference to insert into the collection. But every time I insert into the collection, it comes out as a string or an object. How can I programmatically insert a reference typed value?

---

It's definitely possible to do it in the UI:

Redistrict

Answer 1

Probably the simplest solution is to set the value of a reference key to a doc(collection/doc_key) because a DocumentReference is needed.

Example code:

post = {
  content: "content...",
  title: "impressive title",
  user: db.doc('users/' + user_key),
};

db.collection('posts').add(post)

Toner

Great tip. I didn't understand this answer until I realized that Firestore recognizes the reference and applies it automatically. I had thought this suggestion was saying to duplicate the data, I was way off! – Rydder

great answer thank you for setting me on the right track. – Hotbed

It only worked after I removed .ref from db.doc('users/' + user_key).ref since db.doc() itself returns a DocumentReference. – Velma

how can we find the user_key? – Niggle

Hi, wanted to use reference in my project; how can I use this in python? – Pursuant

Answer 2

I was trying to figure this out today and the solution I came to was to use the .doc() to create a doc reference

  firebase.firestore()
    .collection("applications")
    .add({
      property: firebase.firestore().doc(`/properties/${propertyId}`),
      ...
    })

This will store a DocumentReference type on the property field so when reading the data you will be able to access the document as so

  firebase.firestore()
    .collection("applications")
    .doc(applicationId)
    .get()
    .then((application) => {
      application.data().property.get().then((property) => { ... })
    })

Occasional

is that property field is DocumentReference or String in model? – Bit

This doesn't seem to work for me though. I still get the error ERROR FirebaseError: Function addDoc() called with invalid data and if I just set the string it stores, meaning that this object/line of code causes this error. I tried adding .ref to cast it to a DocumentReference but now it doesn't seem to execute at all. – Wavemeter

Answer 3

This is the model class to store in firestore.

import { AngularFirestore, DocumentReference } from '@angular/fire/firestore';

export class FlightLeg {
  date: string;
  type: string;

  fromRef: DocumentReference; // AYT Airport object's KEY in Firestore
  toRef: DocumentReference;   // IST  {key:"IST", name:"Istanbul Ataturk Airport" }
}

I need to store FlightLeg object with reference value. In order to do this:

export class FlightRequestComponent {

  constructor(private srvc:FlightReqService, private db: AngularFirestore) { }

  addFlightLeg() {
    const flightLeg = {
      date: this.flightDate.toLocaleString(),
      type: this.flightRevenue,
      fromRef: this.db.doc('/IATACodeList/' + this.flightFrom).ref,
      toRef: this.db.doc('/IATACodeList/' + this.flightTo).ref,
    } as FlightLeg
    .
    ..
    this.srvc.saveRequest(flightLeg);
  }

The service which can save the object with referenced to another object into firestore:

export class FlightReqService {
   .
   ..
   ...
  saveRequest(request: FlightRequest) {
    this.db.collection(this.collRequest)
           .add(req).then(ref => {
              console.log("Saved object: ", ref)
           })
   .
   ..
   ...
  }
}

Cocainize

".ref" worked for me – Giannini

Answer 4

The value of the field must be of type DocumentReference. It looks like you're putting some other object in there that has a property called id that's a string.

Uno

Do I have to implement all those fields and functions? – Redistrict

When working with the Firestore JavaScript SDK, you naturally work with those objects. Whatever AngularFire does must be wrapping that object. You'll have to get a hold of the underlying DocumentReference. – Uno

Thanks! I just set the value to the DocumentReference that was returned form a query: i.imgur.com/MIY5HFU.png – Redistrict

@Redistrict : that is a useful image. it should be working up into the queston. (with text not an image) – Holeandcorner

@DougStevenson, I now need to perform a where query on a field that's of type reference. Is that possible? If it's complicated, I can make another stackoverflow question. – Redistrict

If you have a followup question that's different than the first, you should definitely ask it separately. – Uno

You can import DocumentReference like this: import * as firebase from 'firebase/app'; export interface Message { text: string; userReference: firebase.firestore.DocumentReference; } – Stillwell

Answer 5

It seems there may have been a recent update that has made the above answers outdated now. Funnily enough, the solution is even easier now. They've removed the .ref option, but the ref is automatically gotten now.

So you can just do:

const member = this3.$Firestore.doc('users/' + user2.user.uid);
this3.$Firestore.collection('teams').doc(this3.teamName).set({
  name: this3.teamName,
  members: [member],
});

Where member is the doc reference, simple as that. (Ignore the this3 lol.)

Ramify