How to pass a custom style to MUI V5 styled component?

Question

Using MUI V5, how can I pass a custom style to a button component? Here is what I have been trying to merge the old way with the new MUI v5 but it's not working.

import { Button } from "@mui/material";
import { styled } from "@mui/material/styles";
import React from "react";

const StyledButton = styled(Button)(({ theme }) => ({
  root: {
    minWidth: 0,
    margin: theme.spacing(0.5),
  },
  secondary: {
    backgroundColor: theme.palette.secondary.light,
    "& .MuiButton-label": {
      color: theme.palette.secondary.main,
    },
  },
  primary: {
    backgroundColor: theme.palette.primary.light,
    "& .MuiButton-label": {
      color: theme.palette.primary.main,
    },
  },
}));

export default function ActionButton(props) {
  const { color, children, onClick } = props;

  return (
    <Button
      className={`${StyledButton["root"]} ${StyledButton[color]}`}
      onClick={onClick}
    >
      {children}
    </Button>
  );
}

Now I would like to call this Button and give it color="secondary"

import ActionButton from "./ActionButton";
import { Close } from "@mui/icons-material";
export default function Header() {
    return (
       <ActionButton color="secondary">
            <Close />
       </ActionButton>  
     
   )
}

Answer 1

It looks like your code was an attempt to migrate from code using makeStyles/useStyles, but styled works quite a bit differently. You can't use it to generate multiple CSS classes like makeStyles does (StyledButton["root"] and StyledButton[color] will be undefined). styled will generate a single CSS class that is then passed in the className prop to the wrapped component (e.g. Button). Instead of trying to create multiple CSS classes with logic to decide which class to apply, with styled you can leverage props (e.g. the color prop) to generate dynamic styles within the single CSS class that is generated.

Below is an example that I think achieves the effect your code was aiming for. My example doesn't do anything with MuiButton-label because that class doesn't exist in v5 (and the <span> that the class was applied to inside the <button in v4 also does not exist), and I believe the default Button styles set color as desired when the color prop is allowed to passed through to Button.

import Button from "@mui/material/Button";
import { styled } from "@mui/material/styles";

const StyledButton = styled(Button)(({ theme, color }) => ({
  minWidth: 0,
  margin: theme.spacing(0.5),
  backgroundColor: color ? theme.palette[color].light : undefined
}));

export default StyledButton;