Question

我正在尝试使用材质ui开发侧边栏菜单。我可以列出简单的清单。在我的项目中，我有一个无法实现的嵌套侧边栏菜单要求。如果我尝试使用递归函数，则仅提供主标题菜单，而不呈现子元素。请帮助我开发它。

嵌套侧边栏菜单的代码如下，

import React, {useState} from 'react';
import { makeStyles } from '@material-ui/core/styles';
import List from '@material-ui/core/List';
import ListItem from '@material-ui/core/ListItem';
import ListItemIcon from '@material-ui/core/ListItemIcon';
import ListItemText from '@material-ui/core/ListItemText';
import Collapse from '@material-ui/core/Collapse';
import ExpandLess from '@material-ui/icons/ExpandLess';
import ExpandMore from '@material-ui/icons/ExpandMore';

const useStyles = makeStyles((theme) => ({
  root: {
    width: '100%',
    maxWidth: 360,
    backgroundColor: theme.palette.background.paper,
  },
  nested: {
    paddingLeft: theme.spacing(4),
  },
}));

export const Menu = ({items}) => {
  const classes = useStyles();
  const [open, setOpen] = useState(true);

  const handleClick = () => {
    setOpen(!open);
  };

  return (
    items.map(item =>
      !item.children ? (
          <div key={item.title}>
            <ListItem button>
              <ListItemIcon>
                {item.icon}
              </ListItemIcon>
              <ListItemText primary={item.title} />
            </ListItem>
          </div>
        ) : (
          <div
            component="nav"
            key={item.title}
          >
            <ListItem button onClick={handleClick}>
              <ListItemIcon>
                {item.icon}
              </ListItemIcon>
              <ListItemText primary={item.title} />
              {open ? <ExpandLess /> : <ExpandMore />}
            </ListItem>
            <Collapse in={open} timeout="auto" unmountOnExit>
              <List component="div" disablePadding>
                <ListItem button className={classes.nested}>
                  <ListItemIcon>
                    {item.icon}
                  </ListItemIcon>
                  <ListItemText>
                    <Menu items={item} />
                  </ListItemText>
                </ListItem>
              </List>
            </Collapse>
          </div>
        )
    )
  );
}

菜单项代码在这里，

import HomeOutlinedIcon from "@material-ui/icons/HomeOutlined";
import LocalLibraryOutlinedIcon from "@material-ui/icons/LocalLibraryOutlined";
import TrendingUpOutlinedIcon from "@material-ui/icons/TrendingUpOutlined";
import DescriptionOutlinedIcon from "@material-ui/icons/DescriptionOutlined";
import React from "react";


export const menu = [
  {
    icon: <HomeOutlinedIcon/>,
    title: 'Home',
    items: []
  },
  {
    icon: <LocalLibraryOutlinedIcon/>,
    title: 'Education',
    items: [
      {
        title:'Technical Analysis',
        items: [
          {
            title: 'The Dow Theory',
            to: '/thedowtheory'
          },
          {
            title: 'Charts & Chart Patterns',
            to: '/chart'
          },
          {
            title: 'Trend & Trend Lines',
            to: '/trendlines'
          },
          {
            title: 'Support & Resistance',
            to: '/sandr'
          },
        ]
      },
      {
        title:'Fundamental Analysis',
        items: [
          {
            title: 'The Dow Theory',
            to: '/thedowtheory'
          },
          {
            title: 'Charts & Chart Patterns',
            to: '/chart'
          },
          {
            title: 'Trend & Trend Lines',
            to: '/trendlines'
          },
          {
            title: 'Support & Resistance',
            to: '/sandr'
          },
        ]
      },
      {
        title:'Elliot Wave Analysis',
        items: [
          {
            title: 'The Dow Theory',
            to: '/thedowtheory'
          },
          {
            title: 'Charts & Chart Patterns',
            to: '/chart'
          },
          {
            title: 'Trend & Trend Lines',
            to: '/trendlines'
          },
          {
            title: 'Support & Resistance',
            to: '/sandr'
          },
        ]
      },
      ]
  },
  {
    icon: <TrendingUpOutlinedIcon/>,
    title: 'Options'
  },
  {
    icon: <DescriptionOutlinedIcon/>,
    title: 'Blog'
  },
]

Answer 1

首先，您有错字。您正在按children键而不是items循环。但是，即使您修复了该错误，您的代码仍无法按照您想要的方式工作。

我将通过创建SingleLevel和MultiLevel可重用组件来处理当前菜单项来简化方法。如果当前项具有children / items，那么我将使用MultiLevel组件，其他SingleLevel。

单级组件

const SingleLevel = ({ item }) => {
  return (
    <ListItem button>
      <ListItemIcon>{item.icon}</ListItemIcon>
      <ListItemText primary={item.title} />
    </ListItem>
  );
};

多级组件

const MultiLevel = ({ item }) => {
  const { items: children } = item;
  const [open, setOpen] = useState(false);

  const handleClick = () => {
    setOpen((prev) => !prev);
  };

  return (
    <React.Fragment>
      <ListItem button onClick={handleClick}>
        <ListItemIcon>{item.icon}</ListItemIcon>
        <ListItemText primary={item.title} />
        {open ? <ExpandLessIcon /> : <ExpandMoreIcon />}
      </ListItem>
      <Collapse in={open} timeout="auto" unmountOnExit>
        <List component="div" disablePadding>
          {children.map((child, key) => (
            <MenuItem key={key} item={child} />
          ))}
        </List>
      </Collapse>
    </React.Fragment>
  );
};

要确定要使用哪个组件，我将创建一个hasChildren帮助函数，如果当前项目满足我定义的所有条件都将被视为父菜单项，则返回true。

utils.js

export function hasChildren(item) {
  const { items: children } = item;

  if (children === undefined) {
    return false;
  }

  if (children.constructor !== Array) {
    return false;
  }

  if (children.length === 0) {
    return false;
  }

  return true;
}

然后我将所有这些抽象到另一个MenuItem组件上。

MenuItem组件

const MenuItem = ({ item }) => {
  const Component = hasChildren(item) ? MultiLevel : SingleLevel;
  return <Component item={item} />;
};

最后，这就是我将如何循环menu项

export default function App() {
  return menu.map((item, key) => <MenuItem key={key} item={item} />);
}

Answer 2

我已经修复了您的代码，并进行了一些重构。希望您可以使它更干净。.

import React, { useState } from "react";
import List from "@material-ui/core/List";
import ListItem from "@material-ui/core/ListItem";
import ListItemIcon from "@material-ui/core/ListItemIcon";
import ListItemText from "@material-ui/core/ListItemText";
import Collapse from "@material-ui/core/Collapse";
import ExpandLess from "@material-ui/icons/ExpandLess";
import ExpandMore from "@material-ui/icons/ExpandMore";

const ListItemBody = ({config}) => {
  return (<>
      <ListItemIcon>{config.icon}</ListItemIcon>
      <ListItemText primary={config.title} />
  </>);
}

const MenuItem = ({ config }) => {
  return (
    <ListItem button>
      <ListItemBody config={config}/>
    </ListItem>
  );
};

const ExpandableMenuItem = ({ config }) => {
  const [open, setOpen] = useState(false);

  const handleClick = () => {
    setOpen(!open);
  };

  return (
    <div component="nav">
      <ListItem button onClick={handleClick}>
        <ListItemBody config={config}/>
        {open ? <ExpandLess /> : <ExpandMore />}
      </ListItem>
      <Collapse in={open} timeout="auto" unmountOnExit>
        <Menu items={config.items} />
      </Collapse>
    </div>
  );
};

export default function Menu({ items }) {
  const createList = (items) => {
    let menu = [];
    items.map((menuItem) => {
      if (Array.isArray(menuItem.items) && menuItem.items.length > 0) {
        menu.push(<ExpandableMenuItem
          config={menuItem}
          key={menuItem.title}
        />);
      } else {
        menu.push(<MenuItem
          config={menuItem}
          key={menuItem.title}
        />);
      }
    });
    return menu.concat();
  };

  return <List>{createList(items)}</List>;
}

index.js（用法）

import React from "react";
import ReactDOM from "react-dom";
import Demo from "./demo";
import HomeOutlinedIcon from "@material-ui/icons/HomeOutlined";
import LocalLibraryOutlinedIcon from "@material-ui/icons/LocalLibraryOutlined";
import TrendingUpOutlinedIcon from "@material-ui/icons/TrendingUpOutlined";
import DescriptionOutlinedIcon from "@material-ui/icons/DescriptionOutlined";

export const menu = [
  {
    icon: <HomeOutlinedIcon />,
    title: "Home",
    items: []
  },
  {
    icon: <LocalLibraryOutlinedIcon />,
    title: "Education",
    items: [
      {
        title: "Technical Analysis",
        items: [
          {
            title: "The Dow Theory",
            to: "/thedowtheory"
          },
          {
            title: "Charts & Chart Patterns",
            to: "/chart"
          },
          {
            title: "Trend & Trend Lines",
            to: "/trendlines"
          },
          {
            title: "Support & Resistance",
            to: "/sandr"
          }
        ]
      },
      {
        title: "Fundamental Analysis",
        items: [
          {
            title: "The Dow Theory1",
            to: "/thedowtheory"
          },
          {
            title: "Charts & Chart Patterns",
            to: "/chart"
          },
          {
            title: "Trend & Trend Lines",
            to: "/trendlines"
          },
          {
            title: "Support & Resistance",
            to: "/sandr"
          }
        ]
      },
      {
        title: "Elliot Wave Analysis",
        items: [
          {
            title: "The Dow Theory",
            to: "/thedowtheory"
          },
          {
            title: "Charts & Chart Patterns",
            to: "/chart"
          },
          {
            title: "Trend & Trend Lines",
            to: "/trendlines"
          },
          {
            title: "Support & Resistance",
            to: "/sandr"
          }
        ]
      }
    ]
  },
  {
    icon: <TrendingUpOutlinedIcon />,
    title: "Options"
  },
  {
    icon: <DescriptionOutlinedIcon />,
    title: "Blog"
  }
];
ReactDOM.render(<Demo items={menu} />, document.querySelector("#root"));

带有材质ui和Reactjs的嵌套侧边栏菜单

2 个答案: