当我单击该复选框时,虽然onChange处理程序中的console.log指示状态更改为false,但复选标记不会消失.另一方面,当通过单独的按钮改变状态时,复选标记正确地打开和关闭.
export default class TestComponent extends Component {
constructor(props) {
super(props);
this.state = {
is_checked: true
};
this.updateCheckbox = this.updateCheckbox.bind(this);
this.pressButton = this.pressButton.bind(this);
}
updateCheckbox(event) {
event.preventDefault();
this.setState({is_checked: !this.state.is_checked});
console.log(this.state.is_checked); // This logs 'false' meaning the click did cause the state change
console.log(event.target.checked); // However, this logs 'true' because the checkmark is still there
}
pressButton(event){
event.preventDefault();
this.setState({is_checked: !this.state.is_checked});
}
render(){
return (
<input type="checkbox" onChange={this.updateCheckbox} checked={this.state.is_checked} ></input>
<button onClick={this.pressButton}>change checkbox state using button</button>
);
}
}
我正在尝试以编程方式将图像按钮添加到作为viewpager一部分的片段中.我尝试了不同的代码,但即使Eclipse没有返回任何错误也没有按钮显示.
我在这里发现了一个类似的问题,但答案并没有帮助我让我的按钮出现.
这是我的代码.
public class ViewPagerFragment extends Fragment {
private ViewPagerActivity mViewPagerActivity;
private String mId;
public ViewPagerFragment(String id) {
mId = id;
}
@Override
public void onAttach(Activity activity) {
if (activity instanceof ViewPagerActivity) {
mViewPagerActivity = (ViewPagerActivity)activity;
}
super.onAttach(activity);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment, container, false);
int[] image_array = {
R.drawable.elebutton,
R.drawable.right,
R.drawable.middle,
};
for (int i =0;i<image_array.length;i++){
ImageButton b1 = new ImageButton(getActivity());
b1.setId(100 + i); …Shared_preferences ( https://pub.dev/packages/shared_preferences ) 似乎不适用于 Flutter for Web。
我有按下按钮时调用的以下函数。
getEmail() async {
print("reached 1st line");
SharedPreferences prefs = await SharedPreferences.getInstance();
print("reached 2nd line");
String _confirmedEmail = prefs.getString('_confirmedEmail') ?? "";
)
它打印“到达第一行”而不是“到达第二行”，这意味着程序没有通过 await 语句。有趣的是，我也没有收到任何错误。它似乎只是忽略了 await 语句之后的其余函数。
在 Flutter for Web 中存储共享首选项的最佳选择是什么？
当我尝试检查特定文件的存在时,我得到了 java.lang.illegalArgumentException: File contains a path separator
使用getFileStreamPath(..)执行此操作的正确方法是什么？
File file = getActivity().getFileStreamPath("mnt/sdcard/photo/1342147146535.jpg");
if(file.exists()){
Toast.makeText(getActivity(), "File exists in /mnt", Toast.LENGTH_SHORT);
}
我也尝试了以下代码来替换上面代码的第一行.这些都没有奏效.
File file = getActivity().getFileStreamPath("file:///mnt/sdcard/photo/aviary_1342147146535.jpg");
File file = getActivity().getFileStreamPath("/mnt/sdcard/photo/1342147146535.jpg");
// File file = getActivity().getFileStreamPath("mnt/sdcard/photo/1342147146535.jpg");
// File file = getActivity().getFileStreamPath("file:///mnt/sdcard/photo/1342147146535.jpg");
if(file.exists()){
Toast.makeText(getActivity(), "File exists in /mnt", Toast.LENGTH_SHORT);}
else {
Toast.makeText(getActivity(), "File NOT exists in /mnt", Toast.LENGTH_SHORT);}
我开始学习AngularJS $资源,并注意到$ resource对象有一些附加到从服务器下载的数据的方法(参见下面的示例).如何删除这些方法并将对象转换为常规(数组)对象？
__proto__: Resource $delete: function (params, success, error) {$get: function (params, success, error) {$query: function (params, success, error) {$remove: function (params, success, error) {$save: function (params, success, error) {constructor: function Resource(value) {toJSON: function () {__proto__: Object
例如,我正在尝试使用$ resource.save发送包含一些键值数据的POST请求,但是数组中的这些" proto "项在某种程度上导致数据在传递给$ .param时变为"未定义"(数据) )在工厂里.我可以轻松地使用$ http做同样的事情,但想学习$ resource.谢谢!
控制器内部
$scope.ok = function () {
$scope.entry = new calEntry();
$scope.entry.data = data // data is $resource object including _proto_ items
$scope.entry.$save( function(){
toaster.pop('success','Message','Update successfully completed.');
});
};
厂
myApp.factory("calEntry",['$resource','$filter', function($resource, $filter) {
return …我正在尝试从App Engine连接到Firebase,但在尝试使用Python-Firebase包装器导入Firebase时出现此错误:
File "C:\_dev\PycharmProjects\myapp\project\project_handler.py", line 31, in <module>
from firebase import firebase
File "C:\_dev\PycharmProjects\myapp\external\firebase\__init__.py", line 3, in <module>
from .async import process_pool
File "C:\_dev\PycharmProjects\myapp\external\firebase\async.py", line 1, in <module>
import multiprocessing
File "C:\PYTHON27\lib\multiprocessing\__init__.py", line 65, in <module>
from multiprocessing.util import SUBDEBUG, SUBWARNING
File "C:\PYTHON27\lib\multiprocessing\util.py", line 40, in <module>
from subprocess import _args_from_interpreter_flags
ImportError: cannot import name _args_from_interpreter_flags
其他人似乎有同样的问题,但我无法在任何地方找到答案.
我的Elm程序可以正常使用下面的代码(摘录)http.get,但我不得不将其更改为自定义请求以在标头中指定JWT,并且由于类型不匹配而出现以下错误.
我想我需要的类型更改request到Http.Request (List QFields),但不知道如何.显然,我不能说它{ verb = "Get" ...} decoder因为{ verb ... }不是一个功能.
The 2nd argument to function `send` is causing a mismatch.
264| Http.send FetchHNTopStories request
^^^^^^^
Function `send` is expecting the 2nd argument to be:
Http.Request (List QFields)
But it is:
Request
<Working code>
request : Http.Request (List QFields)
request =
let
decoder =
JD.at [ "data", "qQry" ] <|
JD.list qDecoder
in
Http.get ("http://localhost:3000/graphql?query=" ++ encoded) decoder
type …我正在尝试按照此处的说明加载Radium(这是一个内联css的javascript库).
在app.browserify.js:Radium = require("radium");.
在package.json:"radium": "0.13.4"
但是,当我尝试在应用程序中的js中使用Radium时,内联css不起作用.Chrome开发工具表明了这一点Radium = module.exports(ComposedComponent)..
我假设这应该是一个对象,考虑到我以相同方式加载的ReactPIXI,工作正常,开发工具说ReactPIXI = Object {factories: Object}.
这是我的代码:
AppBody = React.createClass({
mixins: [ReactMeteorData, Navigation, State, Radium.StyleResolverMixin,
Radium.BrowserStateMixin],
render: function() {
var self = this;
var styles = {
base: {
color: this.state.fontColor,
background: 'red',
states: [
{hover: {background: 'blue', color: 'red'}},
{focus: {background: 'pink', outline: 'none', color: 'yellow'}}
]
//also tried
//':hover': {background: 'blue', color: 'red'},
//':focus': {background: 'pink', outline: …在我的redux js app(google appengine后端)中,当打开包含Root组件的页面时,我收到以下警告和错误消息.
警告:propType失败:提供store的类型的无效prop ,预期.检查渲染方法.bundle.js:6169functionProviderobjectRoot
警告:propType失败:提供store的类型的无效prop ,预期.检查渲染方法.bundle.js:6169functionDevToolsWrapperobjectRoot
警告:失败的上下文类型:提供store的类型的子上下文无效,是预期的.检查渲染方法.bundle.js:6169functionProviderobjectRoot
警告:无法上下文类型:无效的上下文store类型的function供给Connect(AsyncApp),预计object.检查渲染方法Provider.
Uncaught TypeError: store.getState is not a function
这是react-redux的lib/components/createConnect.js中发生错误的地方.
function computeStateProps(store, props) {
var state = store.getState(); <<<<< The error occurs here.
var stateProps = shouldUpdateStateProps ? finalMapStateToProps(state, props) : finalMapStateToProps(state);
_invariant2['default'](_utilsIsPlainObject2['default'](stateProps), '`mapStateToProps` must return an object. Instead received %s.', stateProps);
return stateProps; …我需要在定义用户身份验证令牌SessionController为处于可用layout/app.html.eex.
我的SessionController定义了一个令牌并将其分配给一个令牌conn.
token = Phoenix.Token.sign(conn, "user socket", user)
assign(conn, :user_token, token)
然后,当我尝试app.html.eex像下面这样使用令牌时,
<script>window.userToken = "<%= assigns[:user_token] %>"</script>
or
<script>window.userToken = "<%= @user_token %>"</script>
我收到此错误: (ArgumentError) assign @user_token not available in eex template.