Save Bookmark Article in Firebase Flutter - firebase

Question

In Flutter app I want to fetch data list
I want to save bookmark any article from article list in Fire store data base but when bookmark button tapped the same article save in the database every time. I want that article should save in database for the first time
Does anyone lead me to the correct way? Any help is highly appreciated!
My code
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
void main() => runApp( MyHomePage());
class MyHomePage extends StatefulWidget {
#override
_MyHomePage createState() => _MyHomePage();
}
class _MyHomePage extends State<MyHomePage> {
String title;
String subtitle;
int id;
Firestore firestore = Firestore.instance;
DocumentSnapshot document;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('jdj'),
),
body: Container(
child: ListView(
children: <Widget>[
stremBuilder(),
Container(
height: 310,
color: Colors.amber,
)
],
),
));
}
Widget stremBuilder() {
return Container(
height: 200,
child: StreamBuilder(
stream: Firestore.instance.collection("User").snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData)
return Center(
child: Text("Loding"),
);
return ListView.builder(
itemCount: snapshot.data.documents.length,
itemBuilder: (context, index) {
return listItem(context, snapshot.data.documents[index]);
},
);
},
),
);
}
Widget listItem(BuildContext context, DocumentSnapshot document) {
return ListTile(
title: Text(document["title"]),
subtitle: Text(document["subtitle"]),
trailing: GestureDetector(
child: Icon(Icons.bookmark),
onTap: () {
setState(() {
saveData(id, document);
});
}),
);
}
Map<String, dynamic> savedata = {};
saveData(int id, DocumentSnapshot document) {
Map<String, dynamic> savedata = {
"id": id,
"saveTitle": document["title"],
'saveSubtitle': document["subtitle"]
};
Firestore.instance.collection("savedata").add(savedata);
}
}

Answer 1

It looks like on the right track. Checking the code, the tapped List item should be saved. If what you're looking for is to save the "bookmark" only once, and clicking on it again should remove the saved bookmark. Then you can delete the document upon pressing again.
await FirebaseFirestore.instance.collection('savedata').doc(docId).delete();
Make sure to keep track of the id of the document that you'd like to delete to be used as reference.