I am trying to query a Firestore sub collection in an ionic 4 app/angular app. My database looks as follows people(id) ----> tasks(id) 

```
{ description : this is a description about a cat,<br>
  title: this is a cat <br>
  category: cat } 

```

I am using a Firestore function to query all of the data in the collection. This is what the Firestore function looks like: 

```
import * as functions from 'firebase-functions';

import * as admin from 'firebase-admin'

admin.initializeApp()

    export const getFeed = functions.https.onCall(async (req,res) =>{
    const docs = await 
    admin.firestore().collection('people').limit(5).get()

    return docs.docs.map(doc => {
    return {
        postID: doc.id,
        ...doc.data()
       }
    })
 })

```

the typescript home.ts file looks like this : 

```
    const getFeed = this.aff.httpsCallable('getFeed')
    this.posts = getFeed({}).subscribe(data=> {
      console.log(data)
      // this.posts = data
        })
    }

```

I've tried to use the array-contains option to query, but it doesn't 
work. The array shows up empty on the console.

```
   export const getFeed = functions.https.onCall(async (req,res) =>{
    const docs = await 
    admin.firestore().collection('people').where("category", 
    "array- 
    contains", "cat").limit(5).get()

    return docs.docs.map(doc => {
    return {
        postID: doc.id,
        ...doc.data()
       }
    })
 })

```