flutter riverpod ConsumerWidget not being rebuilt

Question

我刚刚在我编写的一个小应用程序中实现了riverpod。

flatter_riverpod:^0.12.1

我的问题是，当我更新提供程序时，尽管调用了"watch"，但小部件并没有被重建。

提供者基本上跟踪应该显示的当前页面。

import 'dart:developer';
import 'package:flutter_riverpod/flutter_riverpod.dart';
final currentPageProvider = StateNotifierProvider((ref) => CurrentPage());
class CurrentPage extends StateNotifier<int> {
CurrentPage() : super(-1);
set currentPage(int page) {
log('currentPage set to $page');
state = page;
}
int get currentPage => state;
}

PageButtons小部件绘制一组RaisedButtons。当用户单击其中一个凸起的按钮时，当前页码应该更改，PageButton小部件应该重新构建，这样我们就可以更改与当前页面对应的RaisedButton的颜色。

import 'dart:developer';
import 'dart:math' hide log;
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:fsm2/fsm2.dart' hide State;
import 'package:fsm2_viewer/src/providers/current_page.dart';
import 'package:fsm2_viewer/src/providers/log_provider.dart';
class PageButtons extends ConsumerWidget {
final List<SvgFile> pages;
PageButtons(this.pages);
@override
Widget build(BuildContext context, ScopedReader watch) {
/// watch the currentPageProvider so we are rebuilt when the page
/// no changes.
int currentPage = watch(currentPageProvider).currentPage;
log('building PageButons currentPage: $currentPage');
if (pages.length == 0) {
return Container(width: 0, height: 0);
}
currentPage = min(currentPage, pages.length - 1);
var buttons = <Widget>[];
for (var pageNo = 0; pageNo < pages.length; pageNo++) {
buttons.add(Padding(
padding: EdgeInsets.only(right: 5, left: 5),
child: RaisedButton(
color: (pageNo == currentPage ? Colors.blue : Colors.grey),
onPressed: () {
context.read(logProvider).log = 'onpressed';
/// User click the page button so update the current page.
context.read(currentPageProvider).currentPage = pageNo;
context.read(logProvider).log = 'changed to page $pageNo';
},
child: Text('${pageNo + 1}'))));
}
return Row(children: buttons);
}
}

你可以在上面的构建方法中看到，我称之为watch:

int currentPage = watch(currentPageProvider).currentPage;

然后在onPressed for a Raised按钮中，我更新当前页面：

onPressed: () {
/// User click the page button so update the current page.
context.read(currentPageProvider).currentPage = pageNo;
context.read(logProvider).log = 'onpressed';                
context.read(logProvider).log = 'changed to page $pageNo';

在我的日志中，我看到：

main:ALL> onpressed
main:ALL> currentPage set to 1
main:ALL> changed to page 1

日志告诉我onPressed方法正在被调用，并且我正在更新currentPageProvider。

但是，PageButtons的生成器没有被调用。

我做错了什么？

Answer 1

import 'dart:developer';
import 'dart:math' hide log;
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:fsm2/fsm2.dart' hide State;
import 'package:fsm2_viewer/src/providers/current_page.dart';
import 'package:fsm2_viewer/src/providers/log_provider.dart';
class PageButtons extends ConsumerWidget {
final List<SvgFile> pages;
PageButtons(this.pages);
@override
Widget build(BuildContext context, ScopedReader watch) {
/// watch the currentPageProvider so we are rebuilt when the page
/// no changes.
int currentPage = watch(currentPageProvider.state);
log('building PageButons currentPage: $currentPage');
if (pages.length == 0) {
return Container(width: 0, height: 0);
}
currentPage = min(currentPage, pages.length - 1);
var buttons = <Widget>[];
for (var pageNo = 0; pageNo < pages.length; pageNo++) {
buttons.add(Padding(
padding: EdgeInsets.only(right: 5, left: 5),
child: RaisedButton(
color: (pageNo == currentPage ? Colors.blue : Colors.grey),
onPressed: () {
context.read(logProvider).log = 'onpressed';
/// User click the page button so update the current page.
context.read(currentPageProvider).currentPage = pageNo;
context.read(logProvider).log = 'changed to page $pageNo';
},
child: Text('${pageNo + 1}'))));
}
return Row(children: buttons);
}
}