Firestore where function not working as expected in Ionic / Angular app

Question

Here is the User collection within my firestore database:

I am trying to use the below method to only return Users where isMechanic === false:

private _mechanics = new BehaviorSubject<User[]>([]);

  get mechanics() {
    return this._mechanics.asObservable();
  }

 return of(
      firebase.firestore().collection("users").where("isMechanic", "==", "false")
        .get()
        .then((docs) => {
          const data = []
          docs.forEach((doc) => {
            data.push(doc);
          });
          this._mechanics.next(data)
          console.log('Mechanics in UsersService:', this._mechanics);
          console.log('Mechanics in UsersService:', this.mechanics);
        }).catch((err) => {
          console.log(err);
        })
    );

No records are currently beingWhen this method is called, an empty array is logged to the console. So no records are being returned even though (as per screenshot) isMechanic is false for this record.

Can someone please tell me what changes are required for this function to work as expected?

It's not working because isMechanic isn't a property on the objects in the array. Have you tried looking in the nested properties to see where the property is? For example, in metadata. I don't use Firestore, but I imagine this should be documented in the official documentation? — Kurt Hamilton
– Kurt Hamilton, Commented May 3, 2020 at 11:36

user9847788 · Accepted Answer · 2020-05-03 11:45:43Z

1

I managed to figure this out just now.

If I replace "false" with false, then the users collection is filtered as expected.

Replacing

firebase.firestore().collection("users").where("isMechanic", "==", "false")

with

firebase.firestore().collection("users").where("isMechanic", "==", false)

returns only users where isMechanic == false

answered May 3, 2020 at 11:45

user9847788

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Comments

Józef Podlecki · Accepted Answer · 2020-05-03 12:13:09Z

0

LoadedMechanics is an empty array:

Then surely user.isMechanic is either undefined or null

Look at the following example

let data = [
{
},
{
   IsMechanic: undefined
},
{
   IsMechanic: null
},
{
   IsMechanic: false
}
]

console.log(data)

data = data.filter(pr => pr.IsMechanic === false)

console.log(data)

filter function ignored most the cases.

Now the question is, what is users object? It looks like an array of documents for me. Usually to get all properties from document you have to use ...data() function.

users.map(user => ({
  id: user.id,
  ...user.data()
}))

did you do that in your this.usersService.users observable?

--Edit

You could change following code

const data = []
docs.forEach((doc) => {
data.push(doc);
this._mechanics.next(data);
});

to

const data = docs.docs.map(doc => ({id: doc.id, ...doc.data()}));
this._mechanics.next(data);

Also according to docs

You should filter boolean properties using literal values, not double quote them

.where("isMechanic", "==", "false")

.where("isMechanic", "==", false)

edited May 3, 2020 at 12:13

answered May 3, 2020 at 11:35

Józef Podlecki

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2 Comments

user9847788 Over a year ago

Thanks for your answer. I've updated my question above as I'm going to try to filter the data when querying it in firebase rather than loading all users initially when there's no need

Józef Podlecki Over a year ago

Updated an answer. get() function in this case returns a query object which contains props like empty, docs. You get map all documents into new array of objects with .map(doc => ({id: doc.id, ...doc.data()}));

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