How to use theme in styles for custom class components

问题

I want to use a theme in parts of my own components that are class based. I cannot get anything to work, all examples in the documentation is for functional components. Basically the theme is defined and I want to use it to style my own components so I can avoid repeating myself and change the code at the higher level and it change everywhere.

My App.js

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

const theme = createMuiTheme({
    palette: {
        primary: {
            light: '#757ce8',
            main: '#3f50b5',
            dark: '#002884',
            contrastText: '#fff',
          },
    },
    overrides: {
        MuiOutlinedInput: {
            disabled: true,
            input: {
                color: 'red'
            }
        }
    }
});

export default class App extends React.Component {
    render() {
        return (
            <ThemeProvider theme={theme}>
                <Nav />
            </ThemeProvider>
        );
    }
}

My Problem file, Nav.js

import React from 'react';
import SearchBar from './SearchBar';
import { makeStyles } from '@material-ui/styles';

const styles = makeStyles(theme => ({
    root: {
        background: theme.background,
    },
  }));

class Nav extends React.Component {
    render() {
        const classes = styles();
        return(
            <div className={classes.root}>
                <SearchBar />
            </div>
        )
    }
}

export default Nav;

回答1:

You cannot use makeStyles with class components. makeStyles returns a custom hook which can only be used in function components. For class components, you can leverage all of the same functionality using withStyles. withStyles wraps your component and injects a classes prop.

Below is a working example based on the code in your question:

import React from "react";

import { withStyles } from "@material-ui/core/styles";

class SearchBar extends React.Component {
  render() {
    return <div>My Search Bar</div>;
  }
}

const styles = theme => ({
  root: {
    backgroundColor: theme.palette.primary.main,
    color: theme.palette.primary.contrastText
  }
});

class Nav extends React.Component {
  render() {
    return (
      <div className={this.props.classes.root}>
        <SearchBar />
      </div>
    );
  }
}
export default withStyles(styles)(Nav);