我想试试新的.net核心.我正在关注https://www.microsoft.com/net/core上的指示,但它无法正常工作.
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dotnet-dev-1.0.0-preview1-002702 : Depends: dotnet-sharedframework-microsoft.netcore.app-1.0.0-rc2-3002702 but it is not going to be installed …我试图通过制作一个简单的应用程序来学习反应,我试图从服务器获取json格式的数据,然后将其渲染到视图.问题是我收到一个错误,它说this.state.data为null.我该如何解决这个问题？代码:
class App extends React.Component {
constructor() {
super();
//Query data
fetch('http://localhost:8080/api?access_token=56d847accb86bddc243d4b93')
.then(response => response.json())
.then((data) => {
this.setState({
data: data
})
})
.catch(err => console.error('Error ', err.toString()));
}
getInitialState() {
return {
data: {}
};
}
render() {
return (
<h1>{this.state.data}</h1>
);
}
}
ReactDOM.render(<App/>, document.getElementById('app'));
我有一个简单的 redux 应用程序，它通过从 api 请求数据来显示文章。我想在等待承诺时显示“正在加载”指示器。我怎样才能实现这个？
我有TestWrapper一个克隆组件element，应该使背景变成蓝色。Test也在做同样的事情，但是设置了color. 我期望渲染的元素具有蓝色背景和红色文本，但它只是red. 这是示例：
const Test: React.FC<{ element: React.ReactElement }> = ({ element }) => {
return React.cloneElement(element, {
const isSelected = useIsSelected();
style: { ...element.props.style, color: isSelected ? 'red' : 'black' }
});
};
const TestWrapper: React.FC<{ element: React.ReactElement }> = ({
element
}) => {
// BackgroundColor is blue
const { backgroundColor } = useTheme();
return React.cloneElement(element, {
style: { ...element.props.style, background: backgroundColor }
});
};
export function App() …我有这样的文件：
/* 1 */
{
"_id" : ObjectId("573f3944a75c951d4d6aa65e"),
"Source" : "IGN",
"Country" : "US"
}
/* 2 */
{
"_id" : ObjectId("573f3d41a75c951d4d6aa65f"),
"Source" : "VG",
"Country" : "Norway"
}
/* 3 */
{
"_id" : ObjectId("573f4367a75c951d4d6aa660"),
"Source" : "NRK",
"Country" : "Norway"
}
/* 4 */
{
"_id" : ObjectId("573f4571a75c951d4d6aa661"),
"Source" : "VG",
"Country" : "Norway"
}
/* 5 */
{
"_id" : ObjectId("573f468da75c951d4d6aa662"),
"Source" : "IGN",
"Country" : "US"
}
以及类似这样的资源列表：
list = ['VG', 'IGN']
我只想返回源等于“ IGN”或“ VG”（列表中的任何元素）的文档
如何使用官方C＃mongodb驱动程序执行此操作？