CODEWITHSUNDEEP
firebaseflutterdartgoogle-cloud-firestore
Jesus Loves You
Jesus Loves You

Reputation: 291

Getting Data from Firestore

So I am using Firebase to retrieve data from firestore, And this is working fine, But now in order to save money and resources I am using a limit of 40 items, so only 40 items come from firebase, but now when the user reaches the end of the list i want the user to be able to get the next 40 items from the firebase data base. And that is what i dont know how to do. To get the next 40 items without having to read the whole 80 items from firebase..

This is my code:

getCountryItems() async{
      QuerySnapshot snapshot = await userCountry
      .orderBy('timeStamp', descending: true)
      .limit(40) //getting only 40 items
      //.orderBy('likesCount', descending: true)
      .getDocuments();

      List<Items> countryPosts = snapshot.documents.map((doc) => Items.fromDocument(doc)).toList();
      setState(() {
        this.countryPosts = countryPosts;
      });
     }

So that is what is getting the First 40 items now i want to get the 40 items after this only after a button is pressed:

FlatButton(
 onPressed: (){}//funtion to get the next 40 items 
);

Upvotes: 1

Views: 73

Answers (1)

user120242
user120242

Reputation: 15268

Reference: https://firebase.google.com/docs/firestore/query-data/query-cursors
Use startAfter to move the cursor to desired position

getCountryItems(paginateAt = 0) async{
      QuerySnapshot snapshot = await userCountry
      .orderBy('timeStamp', descending: true)
      .startAfter(paginateAt)
      .limit(40) //getting only 40 items
      //.orderBy('likesCount', descending: true)
      .getDocuments();

      List<Items> countryPosts = snapshot.documents.map((doc) => Items.fromDocument(doc)).toList();
      setState(() {
        this.countryPosts = countryPosts;
      });
     }

FlatButton(
 onPressed: (){
   getCountryItems(this.countryPosts.last)
 }//funtion to get the next 40 items 
);

Upvotes: 1

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