Question

我的AppBar中有一个菜单，我希望某些项目在有空间时显示为AppBar上的按钮，而在没有空间时显示为现有菜单中的菜单项。也就是说，菜单始终存在，并且菜单中始终有项目。我只是希望某些功能成为AppBar按钮或菜单项，具体取决于屏幕尺寸。

这是一个简化的示例：

<Menu
  id="settings-menu"
  anchorEl={anchorEl}
  open={Boolean(anchorEl)}
  onClose={handleClose}
>
  <Hidden lgUp>
    <MenuItem onClick={logout}>
      <ListItemIcon><ExitToAppIcon /></ListItemIcon>
      <ListItemText primary="Hidden log out" />
    </MenuItem>
  </Hidden>
  <MenuItem onClick={logout}>
    <ListItemIcon><ExitToAppIcon /></ListItemIcon>
    <ListItemText primary="Log out" />
  </MenuItem>
</Menu>

当我打开菜单时，在控制台中收到一条错误消息：

Warning: Function components cannot be given refs. Attempts to access this ref will fail. Did you mean to use React.forwardRef()?

Check the render method of `ForwardRef(Menu)`.
    in Hidden (at NavBar.js:76)
    in ul (created by ForwardRef(List))
    in ForwardRef(List) (created by WithStyles(ForwardRef(List)))
    in WithStyles(ForwardRef(List)) (created by ForwardRef(MenuList))
    in ForwardRef(MenuList) (created by ForwardRef(Menu))
    in div (created by ForwardRef(Paper))
    in ForwardRef(Paper) (created by WithStyles(ForwardRef(Paper)))
    in WithStyles(ForwardRef(Paper)) (created by Transition)
    in Transition (created by ForwardRef(Grow))
    in ForwardRef(Grow) (created by TrapFocus)
    in TrapFocus (created by ForwardRef(Modal))
    in div (created by ForwardRef(Modal))
    in ForwardRef(Portal) (created by ForwardRef(Modal))
    in ForwardRef(Modal) (created by ForwardRef(Popover))
    in ForwardRef(Popover) (created by WithStyles(ForwardRef(Popover)))
    in WithStyles(ForwardRef(Popover)) (created by ForwardRef(Menu))
    in ForwardRef(Menu) (created by WithStyles(ForwardRef(Menu)))
    in WithStyles(ForwardRef(Menu)) (at NavBar.js:70)
    in div (at NavBar.js:50)
    in div (created by ForwardRef(Toolbar))
    in ForwardRef(Toolbar) (created by WithStyles(ForwardRef(Toolbar)))
    in WithStyles(ForwardRef(Toolbar)) (at NavBar.js:48)
    in header (created by ForwardRef(Paper))
    in ForwardRef(Paper) (created by WithStyles(ForwardRef(Paper)))
    in WithStyles(ForwardRef(Paper)) (created by ForwardRef(AppBar))
    in ForwardRef(AppBar) (created by WithStyles(ForwardRef(AppBar)))
    in WithStyles(ForwardRef(AppBar)) (at NavBar.js:47)
    in Header (at Layout.js:32)
    in div (at Layout.js:31)
    in div (at Layout.js:29)
    in Layout (at App.js:18)
    in Unknown (at src/index.js:39)
    in Router (at src/index.js:38)
    in ThemeProvider (at src/index.js:37)
    in Provider (at src/index.js:36)

<Hidden>中是否允许使用<Menu>个组件？如果不是，那么一种允许菜单项根据屏幕大小有条件显示的好方法是什么？

Answer 1

由于错误表明Hidden不支持接收ref，而菜单项是必需的。

但是，您可以使用Box实现相同的目的：

import React from "react";
import Button from "@material-ui/core/Button";
import Menu from "@material-ui/core/Menu";
import MenuItem from "@material-ui/core/MenuItem";
import Box from "@material-ui/core/Box";

export default function SimpleMenu() {
  const [anchorEl, setAnchorEl] = React.useState(null);

  const handleClick = event => {
    setAnchorEl(event.currentTarget);
  };

  const handleClose = () => {
    setAnchorEl(null);
  };

  return (
    <div>
      <Button
        aria-controls="simple-menu"
        aria-haspopup="true"
        onClick={handleClick}
      >
        Open Menu
      </Button>
      <Menu
        id="simple-menu"
        anchorEl={anchorEl}
        keepMounted
        open={Boolean(anchorEl)}
        onClose={handleClose}
      >
        <MenuItem onClick={handleClose}>Always Displayed</MenuItem>
        <Box clone display={{ sm: "none" }}>
          <MenuItem onClick={handleClose}>Profile</MenuItem>
        </Box>
        <Box clone display={{ lg: "none" }}>
          <MenuItem onClick={handleClose}>My account</MenuItem>
        </Box>
        <Box clone display={{ md: "none" }}>
          <MenuItem onClick={handleClose}>Logout</MenuItem>
        </Box>
      </Menu>
    </div>
  );
}

不幸的是，在这样的情况下使用Box可能会很脆弱，因为它会覆盖由包装组件设置的样式，因为导入顺序会影响哪个胜出（请参见此处的进一步讨论：Box vs className vs style for vertical spacing in Material UI）

另一种选择是使用withStyles创建隐藏在特定断点处的MenuItem版本：

import React from "react";
import Button from "@material-ui/core/Button";
import Menu from "@material-ui/core/Menu";
import MenuItem from "@material-ui/core/MenuItem";
import { withStyles } from "@material-ui/core/styles";

const MenuItemHiddenLgUp = withStyles(theme => ({
  root: {
    [theme.breakpoints.up("lg")]: {
      display: "none"
    }
  }
}))(MenuItem);

export default function SimpleMenu() {
  const [anchorEl, setAnchorEl] = React.useState(null);

  const handleClick = event => {
    setAnchorEl(event.currentTarget);
  };

  const handleClose = () => {
    setAnchorEl(null);
  };

  return (
    <div>
      <Button
        aria-controls="simple-menu"
        aria-haspopup="true"
        onClick={handleClick}
      >
        Open Menu
      </Button>
      <Menu
        id="simple-menu"
        anchorEl={anchorEl}
        keepMounted
        open={Boolean(anchorEl)}
        onClose={handleClose}
      >
        <MenuItem onClick={handleClose}>Always Displayed</MenuItem>
        <MenuItemHiddenLgUp onClick={handleClose}>Profile</MenuItemHiddenLgUp>
        <MenuItemHiddenLgUp onClick={handleClose}>
          My account
        </MenuItemHiddenLgUp>
        <MenuItem onClick={handleClose}>Logout</MenuItem>
      </Menu>
    </div>
  );
}

文档：

是否可以在材料UI <菜单>组件中包含<隐藏>菜单项？

1 个答案: