How do you insert a “reference” value into firestore?

问题

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:

回答1:

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

Example code:

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

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

回答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) => { ... })
    })

回答3:

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.

回答4:

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)
           })
   .
   ..
   ...
  }
}

来源：https://stackoverflow.com/questions/51292378/how-do-you-insert-a-reference-value-into-firestore