How to get documents in firestore, whose document IDs are stored in the list?, i.e bring only those documents....?

Question

I have a list that contains the document Ids of a particular collection "users", and I want to get documents only present in this list, and these documents are in "users" collection as mention before.

Code:

  getUsers() async
     {
       double radius = 0.3;
      String field = "GeoPosition";
       print(currentUser.point.longitude);
       GeoFirePoint center = geo.point(latitude: currentUser.point.latitude,  longitude: currentUser.point.longitude);
        var collectionRef = Firestore.instance.collection('user_locations').document(currentUser.pincode)  .collection('Users_complete_address_and_geopoint');
        this.stream =  geo.collection(collectionRef: collectionRef).within(center: center, radius: radius, field: field, strictMode: false);   
        Future<List<certainrangeusers>> users1 =  stream.first.then(
        (documents) => documents.map((doc) => certainrangeusers(
         id: doc['userPhone'],
         )
        ).toList());  
         users1.then((val) async{
        QuerySnapshot snapshot = await  Firestore.instance.collection('users').where('id', isEqualTo: val.first.id).getDocuments();
         List<User> users = snapshot.documents.map((doc) =>  User.fromDocument(doc)).toList();
        setState(() {
         this.users = users;
          });
       });
   }

Firebase Structure: Click here for the firebase structure

Code In image format:

Click here for the image

1. In orange box, "users1" is a list having document IDs...of users 10km users
2. In the pink box, we r using the value of the list...
3. In the green box, we need to pass the document ids present in the above list...

P.s: I am using "val.first.id" just to bring the document present at first in the list........But I need to bring every document present in that list...so that's a point I have struck...

Solution

Here how to search for all documents from the list id

instead of:

await  Firestore.instance.collection('users').where('id', isEqualTo: 
 val.first.id).getDocuments();

use this:

await  Firestore.instance.collection('users').where('id', whereIn: 
 val).getDocuments();

Since you have a list of certainchangeuser, do this to get the ids.

users1.then((val){
  // Get the ids
  List ids = [];
  for (var value in val){
    ids.add(value.id);
  }
  //Then
  QuerySnapshot = await 
    Firestore.instance.collection('users').where('id', 
    whereIn:ids).getDocuments();
....
});

Comments

[Adnan karim]

can you get the document for the first id?

[Sai]

@Adnankarim I was able to get the document for the first Id, i have just uploaded the firebase structure

[Adnan karim]

check my answer, hope it helps.

[Doug Stevenson]

Transactions are for reading then writing documents, not just reading.

[Sai]

As i am new to flutter

[Sai]

Error: "Unhandled Exception: Invalid argument: Instance of 'certainrangeusers' ", got this error

[Adnan karim]

make sure "val" is a list

[Adnan karim]

Well this only takes "id's" not list of "certainrangeusers"

[Sai]

class certainrangeusers { final String id; certainrangeusers({this.id}); }

[Sai]

is the class for the list<certainrangeusers> = [];

[Adnan karim]

Yes your are passing an object that contains id, but it only accepts ids like "List ids = ["23","41","23"]

[Sai]

Future<List<certainrangeusers>> users1 = stream.first.then( (documents) => documents.map((doc) => certainrangeusers( id: doc['userPhone'], ) )

[Sai]

i am doing as above

[Sai]

but it only accepts ids like "List ids = ["23","41","23"] , how to do this....considering my scenario

[Adnan karim]

@saivaraprasadboggula check the answer

[Sai]

Let us continue this discussion in chat.

[Sai]

stackoverflow.com/q/61600322/13462594 , is the continuation of the question