![](/img/trans.png)
[英]Error: Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null
[英]React - Error: App(...): Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null
我正在使用 MERN 和 GraphQL Apollo 创建一个完整的堆栈应用程序。 为了将后端连接到客户端,我使用的是 Apollo Client。 这是代码-
ApolloProvider.js
import React from "react";
import App from "./App";
import {
ApolloClient,
createHttpLink,
InMemoryCache,
ApolloProvider,
} from "@apollo/client";
const httpLink = createHttpLink({ uri: "http://localhost:5000" });
const client = new ApolloClient({
link: httpLink,
cache: new InMemoryCache(),
});
export default (
<ApolloProvider client={client}>
<App />
</ApolloProvider>
);
索引.js
import ReactDOM from "react-dom";
import reportWebVitals from "./reportWebVitals";
import ApolloProvider from "./ApolloProvider";
ReactDOM.render(ApolloProvider, document.getElementById("root"));
// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint.
reportWebVitals();
应用程序.js
import React from "react";
import { BrowserRouter as Router, Route } from "react-router-dom";
import { Container } from "semantic-ui-react";
import "semantic-ui-css/semantic.min.css";
import "./App.css";
import MenuBar from "./components/MenuBar";
import Home from "./pages/Home";
import Login from "./pages/Login";
import Register from "./pages/Register";
function App() {
<Router>
<Container>
<MenuBar />
<Route exact path="/" component={Home} />
<Route exact path="/login" component={Login} />
<Route exact path="/register" component={Register} />
</Container>
</Router>;
}
export default App;
在ReactDOM.render(ApolloProvider, document.getElementById("root"));
错误来了 - '没有从渲染中返回任何东西。 这通常意味着缺少返回语句。 或者,不渲染任何内容,返回 null。
编辑:看起来问题一直在你的App.js
中。 您不返回应用程序的 JSX。 将其添加到:
function App() {
return (
<Router>
<Container>
<MenuBar />
<Route exact path="/" component={Home} />
<Route exact path="/login" component={Login} />
<Route exact path="/register" component={Register} />
</Container>
</Router>
);
}
原答案:
您需要实际渲染ReactDOM.render
中的元素,即
ReactDOM.render(<ApolloProvider/>, document.getElementById("root"));
同样在你的 apollo 提供者中,返回一个功能组件,而不是纯 JSX。 不确定这是否重要,但可能会有所帮助,即
const ApolloApp = () => (
<ApolloProvider client={client}>
<App />
</ApolloProvider>
);
export default ApolloApp;
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