Pagination in firestore api

Question

I am trying to paginate documents with firestore beta. I am following the official docs

I see there is a pageSize param to say how many documents you want to show, b

Answer 1

Firestore range queries are based on an having anchor document. So you must know the (order-by properties of the) document that the range start with, and then use ref.startAfter(anchorDdoc).limit(10) (or ref.startAfter(valueOfAnchorDoc).limit(10)) to get the next page.

The Firestore server-side Admin SDKs have an offset() call that allows the server to determine the document to starts at. But the client-side SDKs do not have this method.

Answer 2

From your documentation link, I assume that you're using the REST API. In the REST API, there is a pageToken parameter, which you can specify. This can be derived from the nextPageToken returned from the previous request.

Previous response

{
  "documents": [
    {
      object(Document)
    }
  ],
  "nextPageToken": ABCDEF1234567890,
}

Next request

 projects/my-project/databases/my-database/documents or projects/my-project/databases/my-database/documents/chatrooms?pageSize=20&pageToken=ABCDEF1234567890

Answer 3

This may help paginating without page numbers (previous and next):

app.get('/page/next/:startAt',(req, res)=>{
      (async ()=>{
          try{
              const startAt = req.params.startAt;
              let query = db.collection('movies');
              let response = [];
              console.log(query);
              await query.orderBy('time', 'desc').where("time", "<", new Date(parseInt(startAt)*1000)).limit(16).get().then(snapshots => {
                let docs = snapshots.docs;

                for (let doc of docs){
                    console.log(doc.data());
                    const selectedItems = {
                        id: doc.id,
                        name: doc.data().name,
                        desp: doc.data().desp,
                        site: doc.data().site,
                        time: doc.data().time
                    }
                    response.push(selectedItems);
                }
                  return response;  //each then should return a vlue
              })
              return res.status(200).send(response);
          }catch (error){
              console.log(error);
              return res.status(500).send(error);
          }
      })();
    });


    app.get('/page/back/:backAt',(req, res)=>{
      (async ()=>{
          try{
              const backAt = req.params.backAt;
              let query = db.collection('movies');
              let response = [];
              console.log(query);
              await query.orderBy('time', 'desc').where("time", ">", new Date(parseInt(backAt)*1000)).limit(16).get().then(snapshots => {
                let docs = snapshots.docs;

                for (let doc of docs){
                    console.log(doc.data());
                    const selectedItems = {
                        id: doc.id,
                        name: doc.data().name,
                        desp: doc.data().desp,
                        site: doc.data().site,
                        time: doc.data().time
                    }
                    response.push(selectedItems);
                }
                  return response;  //each then should return a vlue
              })
              return res.status(200).send(response);
          }catch (error){
              console.log(error);
              return res.status(500).send(error);
          }
      })();
    });