ListView不更新

编程入门行业动态更新时间:2024-10-26 17:31:50

ListView不更新 - ListViewDataSource.js中的错误(ListView not updating – error in ListViewDataSource.js)

我目前正在使用React Native框架显示iOS应用程序。为了允许用户选择可用的蓝牙LE设备，我使用RefreshableListView（NPM包：react-native-refreshable-listview）组件，该组件使用React提供的ListView组件。当我第二次使用该列表（我的应用程序具有离线模式）时，我将其放入单独的组件中并使用属性传递可用设备。组件在方法componentWillReceiveProps: function(newProperties) ，如下所示。

componentWillReceiveProps: function(newProperties) { if (newProperties.devices !== undefined) { if (newProperties.devices.length > 0) { alert("length: " + newProperties.devices.length); // the expected result is shown by this statement this.setState ( { dataSource: this.state.dataSource.cloneWithRows(newProperties.discoveredDevices) } ); } } }

问题是由于以下错误（使用Google Chrome的调试工具捕获），列表视图未更新：

Uncaught TypeError: Cannot convert undefined or null to object ListViewDataSource.js:202

为避免此错误，我尝试初始化数组，如下所示：

componentDidMount: function() { this.setState ( { dataSource: this.state.dataSource.cloneWithRows(new Array()) } ); }

但是，这还没有解决问题。使用静态数据初始化数组（由方法componentDidMount ）也不能修复错误。

我很感激任何建议。提前致谢！

I'm currently displaying an iOS application using the React Native framework. For allowing the user to choose an available Bluetooth LE device I use a RefreshableListView (NPM package: react-native-refreshable-listview) component which uses the ListView component supplied by React. As I use the list a second time (my application has an offline mode) I put it into a separate component and pass the available devices in using properties. The component is updated in the method componentWillReceiveProps: function(newProperties), as shown below.

The problem is that the list view is not updated due to the following error (captured using Google Chrome's debugging tool):

Uncaught TypeError: Cannot convert undefined or null to object ListViewDataSource.js:202

For avoiding this error I have tried to initialize the array as shown below:

componentDidMount: function() { this.setState ( { dataSource: this.state.dataSource.cloneWithRows(new Array()) } ); }

However, this has not solved the issue. Initializing the array with static data (done by the method componentDidMount) does not fix the error too.

I appreciate any advice. Thanks in advance!