71 lines
1.6 KiB
Dart
71 lines
1.6 KiB
Dart
import 'dart:async';
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import 'package:cloud_firestore/cloud_firestore.dart';
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import 'package:fcs/pages/widgets/callbacks.dart';
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import 'package:logging/logging.dart';
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typedef ToObj = Function(Map<String, dynamic> data, String id);
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/*
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* Pagination load data in page
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*/
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class Paginator<T> {
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final log = Logger('Paginator');
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final int rowPerLoad;
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DocumentSnapshot prev;
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bool ended = false;
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bool isLoading = false;
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List<T> values = [];
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ToObj toObj;
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Query pageQuery;
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Paginator(this.pageQuery, {this.rowPerLoad = 20, this.toObj}) {
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_clearState();
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}
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void _clearState() {
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prev = null;
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ended = false;
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isLoading = false;
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values = [];
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}
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void close() {
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_clearState();
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}
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Future<void> refresh({CallBack onFinished}) async {
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_clearState();
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await load();
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if (onFinished != null) onFinished();
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}
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Future<bool> load({CallBack onFinished}) async {
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if (ended) return null;
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isLoading = true;
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Query _query =
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prev != null ? pageQuery.startAfterDocument(prev) : pageQuery;
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try {
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await _query
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.limit(rowPerLoad)
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.getDocuments(source: Source.server)
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.then((QuerySnapshot snapshot) {
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int count = snapshot.documents.length;
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ended = count < rowPerLoad;
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prev = count > 0 ? snapshot.documents[count - 1] : prev;
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snapshot.documents.forEach((e) {
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values.add(toObj(e.data, e.documentID));
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});
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});
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} catch (e) {
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log.warning("Error!! $e");
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} finally {
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isLoading = false;
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if (onFinished != null) onFinished();
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}
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return ended;
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}
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}
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