Why is ThemeProvider (Material UI) not working for me here?

user_6540361 0
Viewed 15211

I've used Material UI quite a lot, so this is baffling. I've looked through the docs, I've checked my code, I can't see the issue. I want my H2 tag in the nested component to use Arial. However, it's rendering using Times. I'm not sure why.

Here's my index.tsx:

import React from "react";
import ReactDOM from "react-dom";
import App from "./components/App";
import { Provider } from "react-redux";
import configureStore from "./redux/stores/main";
import * as serviceWorker from "./serviceWorker";
import { createMuiTheme } from "@material-ui/core";
import myTheme from "./styling/mainTheme";
import { ThemeProvider } from "@material-ui/styles";

const theme = createMuiTheme({
  typography: {
    fontFamily: ["Arial"].join(",")
  }
});

ReactDOM.render(
  <ThemeProvider theme={theme}>
    <Provider store={configureStore()}>
      <App />
    </Provider>
  </ThemeProvider>,
  document.getElementById("root")
);

serviceWorker.unregister();

My app component: 

import React from "react";
import { useSelector } from "react-redux";
import HeaderContainer from "../containers/layout/header/HeaderContainer";
import { ThemeProvider, useTheme } from "@material-ui/styles";
import theme from "../styling/mainTheme";
import { createMuiTheme } from "@material-ui/core";




const App: React.FC = () => {
    const theme = useTheme();
  return (
      <div className="App">
          <HeaderContainer />
      </div>
  );
};

export default App;

The header container (will contain logic):

  import * as React from 'react';
import Header from '../../../components/layout/header/Header';

export interface HeaderContainerProps {
}

export default class HeaderContainer extends React.Component<HeaderContainerProps> {
  public render() {
    return <Header />
  }
}

And finally the header:

import * as React from "react";
import { styled } from "@material-ui/core/styles";
import AppBar from "@material-ui/core/AppBar";





export default function Header() {
    return (
        <AppBar>
            <h2>Hello</h2>
        </AppBar>
    )
}

I've tried putting the ThemeProvider in different components, but my h2 is still rendering as Times. Would be great if someone could spot the issue. Thanks

material-ui reactjs css
2 Answers

Checking the documents of material-ui it turns out you have imported some of the things from library in a wrong way. Like the docs state -

import { useTheme } from '@material-ui/core/styles';
import { createMuiTheme } from '@material-ui/core/styles';

Which can basically be

import { useTheme, createMuiTheme } from '@material-ui/core/styles';

Same goes for ThemeProvider

import { ThemeProvider } from '@material-ui/core/styles';
user_105743850

In MUI V5 you need to import ThemeProvider and createTheme from @mui/material/styles instead of @mui/styles.

import * as React from 'react';
import ReactDOM from 'react-dom';
import {red} from '@mui/material/colors';
import { ThemeProvider, createTheme } from '@mui/material/styles';

const theme = createTheme({
  palette: {
    primary: {
      main: red[500],
    },
  },
});

function App() {
  return <ThemeProvider theme={theme}>...</ThemeProvider>;
}

ReactDOM.render(<App />, document.querySelector('#app'));

source

user_165932750
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