默认根据id打开可折叠菜单

Question

默认根据id打开可折叠菜单

8 html javascript accordion reactjs reactstrap

我正在制作一个嵌套菜单和子菜单，到目前为止一切都已经完成了..我现在需要根据给定的 id 使这个可折叠菜单默认打开..

您还可以查看下面完整的工作代码片段，

const loadMenu = () => Promise.resolve([{id:"1",name:"One",children:[{id:"1.1",name:"One - one",children:[{id:"1.1.1",name:"One - one - one"},{id:"1.1.2",name:"One - one - two"},{id:"1.1.3",name:"One - one - three"}]}]},{id:"2",name:"Two",children:[{id:"2.1",name:"Two - one"}]},{id:"3",name:"Three",children:[{id:"3.1",name:"Three - one",children:[{id:"3.1.1",name:"Three - one - one",children:[{id:"3.1.1.1",name:"Three - one - one - one",children:[{id:"3.1.1.1.1",name:"Three - one - one - one - one"}]}]}]}]},{id:"4",name:"Four"},{id:"5",name:"Five",children:[{id:"5.1",name:"Five - one"},{id:"5.2",name:"Five - two"},{id:"5.3",name:"Five - three"},{id:"5.4",name:"Five - four"}]},{id:"6",name:"Six"}]);

const openMenuId = "3.1.1.1";

const {Component, Fragment} = React;
const {Button, Collapse, Input} = Reactstrap;

class Menu extends Component {
  constructor(props) {
    super(props);
    this.state = {menuItems: []};
  }

  render() {
    return <MenuItemContainer menuItems={this.state.menuItems} />;
  }

  componentDidMount() {
    loadMenu().then(menuItems => this.setState({menuItems}));
  }
}

function MenuItemContainer(props) {
  if (!props.menuItems.length) return null;
  
  const renderMenuItem = menuItem =>
    <li key={menuItem.id}><MenuItem {...menuItem} /></li>;
    
  return <ul>{props.menuItems.map(renderMenuItem)}</ul>;
}
MenuItemContainer.defaultProps = {menuItems: []};

class MenuItem extends Component {
  constructor(props) {
    super(props);
    this.state = {isOpen: false};
    this.toggle = this.toggle.bind(this);
  }

  render() {
    let isLastChild = this.props.children ? false : true;
    return (
      <Fragment>
        <Button onClick={this.toggle}>{this.props.name}</Button>
        <Fragment>
          {isLastChild ? <Input type="checkbox" value={this.props.id} /> : ''}
        </Fragment>
        <Collapse isOpen={this.state.isOpen}>
          <MenuItemContainer menuItems={this.props.children} />
        </Collapse>
      </Fragment>
    );
  }

  toggle() {
    this.setState(({isOpen}) => ({isOpen: !isOpen}));
  }
}

ReactDOM.render(<Menu />, document.getElementById("root"));

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<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.4.1/css/bootstrap.min.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/reactstrap/8.4.1/reactstrap.min.js"></script>

<div id="root"></div>

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要求：

我const openMenuId = "3.1.1.1.1";在父组件中存储了一个 id 值（您可以在loadMenu数组变量下方查看此变量）。

即使有多个子菜单，这个 id 也只属于最后一级的孩子 id，因此肯定会有一个复选框，以便需要选中复选框，并且需要打开父级的菜单。

例如..，

由于openMenuId是"3.1.1.1.1"，因此很显然，菜单的最后一个子级three是Three - one - one - one - one需要检查的openMenuId和值复选框有比赛在这里。然后各个菜单和子菜单需要扩大，直至最后一级。

这仅适用于访问的页面上的默认行为，因此在该用户可以折叠回来并能够检查任何其他菜单中的任何其他复选框之后。需要在复选框中选中..

请帮助我通过比较作为道具传递的 id 并检查相应的菜单来实现打开相应菜单的结果..

挣扎了很长时间，所以请帮助我.. 非常感谢..

Answer 1

cub*_*brr 3

多么好的问题啊！我真的很高兴为这个问题想出一个解决方案。

<Menu>由于您想为菜单状态和复选框状态提供初始状态，我认为在级别（甚至更高！）上控制两者的状态是一个好主意。这不仅可以轻松地从父级定义初始状态，而且如果您将来需要一些更复杂的菜单或复选框行为，它还可以为您提供更大的灵活性。

由于菜单的结构是递归的，我认为菜单状态的递归结构效果很好。在进入代码之前，先看一个简短的 GIF，我希望它能帮助解释状态的样子：

演示

这是操场片段：

const loadMenu = () =>
  Promise.resolve([
    {
      id: "1",
      name: "One",
      children: [
        {
          id: "1.1",
          name: "One - one",
          children: [
            { id: "1.1.1", name: "One - one - one" },
            { id: "1.1.2", name: "One - one - two" },
            { id: "1.1.3", name: "One - one - three" }
          ]
        }
      ]
    },
    { id: "2", name: "Two", children: [{ id: "2.1", name: "Two - one" }] },
    {
      id: "3",
      name: "Three",
      children: [
        {
          id: "3.1",
          name: "Three - one",
          children: [
            {
              id: "3.1.1",
              name: "Three - one - one",
              children: [
                {
                  id: "3.1.1.1",
                  name: "Three - one - one - one",
                  children: [
                    { id: "3.1.1.1.1", name: "Three - one - one - one - one" }
                  ]
                }
              ]
            }
          ]
        }
      ]
    },
    { id: "4", name: "Four" },
    {
      id: "5",
      name: "Five",
      children: [
        { id: "5.1", name: "Five - one" },
        { id: "5.2", name: "Five - two" },
        { id: "5.3", name: "Five - three" },
        { id: "5.4", name: "Five - four" }
      ]
    },
    { id: "6", name: "Six" }
  ]);

const { Component, Fragment } = React;
const { Button, Collapse, Input } = Reactstrap;

const replaceNode = (replacer, node, idPath, i) => {
  if (i <= idPath.length && !node) {
    // Not at target node yet, create nodes in between
    node = {};
  }
  if (i > idPath.length) {
    // Reached target node
    return replacer(node);
  }

  // Construct ID that matches this depth - depth meaning
  // the amount of dots in between the ID
  const id = idPath.slice(0, i).join(".");
  return {
    ...node,
    // Recurse
    [id]: replaceNode(replacer, node[id], idPath, i + 1)
  };
};

const replaceNodeById = (node, id, visitor) => {
  // Pass array of the id's parts instead of working on the string
  // directly - easy way to handle multi-number ID parts e.g. 3.1.15.32
  return replaceNode(visitor, node, id.split("."), 1);
};

const expandedNode = () => ({});
const unexpandedNode = () => undefined;

const toggleNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode =>
    oldNode ? unexpandedNode() : expandedNode()
  );
const expandNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode => expandedNode());

class Menu extends Component {
  constructor(props) {
    super(props);
    this.state = {
      menuItems: [],
      openMenus: {},
      checkedMenus: {}
    };
    this.handleMenuToggle = this.handleMenuToggle.bind(this);
    this.handleChecked = this.handleChecked.bind(this);
  }

  render() {
    const { menuItems, openMenus, checkedMenus } = this.state;

    return (
      <div
        style={{
          display: "flex",
          flexDirection: "row",
          columnCount: 3,
          justifyContent: "space-between"
        }}
      >
        <div style={{ paddingTop: "10px" }}>
          <MenuItemContainer
            openMenus={openMenus}
            menuItems={menuItems}
            onMenuToggle={this.handleMenuToggle}
            checkedMenus={checkedMenus}
            onChecked={this.handleChecked}
          />
        </div>
        <div style={{ padding: "10px", marginLeft: "auto" }}>
          <p>Menu state</p>
          <pre>{JSON.stringify(openMenus, null, 2)}</pre>
        </div>
        <div style={{ padding: "10px", width: "177px" }}>
          <p>Checkbox state</p>
          <pre>{JSON.stringify(checkedMenus, null, 2)}</pre>
        </div>
      </div>
    );
  }

  componentDidMount() {
    const { initialOpenMenuId, initialCheckedMenuIds } = this.props;

    loadMenu().then(menuItems => {
      const initialMenuState = {};
      this.setState({
        menuItems,
        openMenus: expandNodeById(initialMenuState, initialOpenMenuId),
        checkedMenus: initialCheckedMenuIds.reduce(
          (acc, val) => ({ ...acc, [val]: true }),
          {}
        )
      });
    });
  }

  handleMenuToggle(toggledId) {
    this.setState(({ openMenus }) => ({
      openMenus: toggleNodeById(openMenus, toggledId)
    }));
  }

  handleChecked(toggledId) {
    this.setState(({ checkedMenus }) => ({
      checkedMenus: {
        ...checkedMenus,
        [toggledId]: checkedMenus[toggledId] ? unexpandedNode() : expandedNode()
      }
    }));
  }
}

function MenuItemContainer({
  openMenus,
  onMenuToggle,
  checkedMenus,
  onChecked,
  menuItems = []
}) {
  if (!menuItems.length) return null;

  const renderMenuItem = menuItem => (
    <li key={menuItem.id}>
      <MenuItem
        openMenus={openMenus}
        onMenuToggle={onMenuToggle}
        checkedMenus={checkedMenus}
        onChecked={onChecked}
        {...menuItem}
      />
    </li>
  );

  return <ul>{menuItems.map(renderMenuItem)}</ul>;
}

class MenuItem extends Component {
  constructor(props) {
    super(props);
    this.handleToggle = this.handleToggle.bind(this);
    this.handleChecked = this.handleChecked.bind(this);
  }

  render() {
    const {
      children,
      name,
      id,
      openMenus,
      onMenuToggle,
      checkedMenus,
      onChecked
    } = this.props;

    const isLastChild = !children;
    return (
      <Fragment>
        <Button onClick={isLastChild ? this.handleChecked : this.handleToggle}>
          {name}
        </Button>
        {isLastChild && (
          <Input
            addon
            type="checkbox"
            onChange={this.handleChecked}
            checked={!!checkedMenus[id]}
            value={id}
          />
        )}

        <Collapse isOpen={openMenus ? !!openMenus[id] : false}>
          <MenuItemContainer
            menuItems={children}
            // Pass down child menus' state
            openMenus={openMenus && openMenus[id]}
            onMenuToggle={onMenuToggle}
            checkedMenus={checkedMenus}
            onChecked={onChecked}
          />
        </Collapse>
      </Fragment>
    );
  }

  handleToggle() {
    this.props.onMenuToggle(this.props.id);
  }

  handleChecked() {
    this.props.onChecked(this.props.id);
  }
}

ReactDOM.render(
  <Menu initialOpenMenuId="3.1.1.1" initialCheckedMenuIds={["3.1.1.1.1"]} />,
  document.getElementById("root")
);

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<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.4.1/css/bootstrap.min.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/reactstrap/8.4.1/reactstrap.min.js"></script>

<div id="root"></div>

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回答

下面的代码演练。

const loadMenu = () =>
  Promise.resolve([
    {
      id: "1",
      name: "One",
      children: [
        {
          id: "1.1",
          name: "One - one",
          children: [
            { id: "1.1.1", name: "One - one - one" },
            { id: "1.1.2", name: "One - one - two" },
            { id: "1.1.3", name: "One - one - three" }
          ]
        }
      ]
    },
    { id: "2", name: "Two", children: [{ id: "2.1", name: "Two - one" }] },
    {
      id: "3",
      name: "Three",
      children: [
        {
          id: "3.1",
          name: "Three - one",
          children: [
            {
              id: "3.1.1",
              name: "Three - one - one",
              children: [
                {
                  id: "3.1.1.1",
                  name: "Three - one - one - one",
                  children: [
                    { id: "3.1.1.1.1", name: "Three - one - one - one - one" }
                  ]
                }
              ]
            }
          ]
        }
      ]
    },
    { id: "4", name: "Four" },
    {
      id: "5",
      name: "Five",
      children: [
        { id: "5.1", name: "Five - one" },
        { id: "5.2", name: "Five - two" },
        { id: "5.3", name: "Five - three" },
        { id: "5.4", name: "Five - four" }
      ]
    },
    { id: "6", name: "Six" }
  ]);

const { Component, Fragment } = React;
const { Button, Collapse, Input } = Reactstrap;

const replaceNode = (replacer, node, idPath, i) => {
  if (i <= idPath.length && !node) {
    // Not at target node yet, create nodes in between
    node = {};
  }
  if (i > idPath.length) {
    // Reached target node
    return replacer(node);
  }

  // Construct ID that matches this depth - depth meaning
  // the amount of dots in between the ID
  const id = idPath.slice(0, i).join(".");
  return {
    ...node,
    // Recurse
    [id]: replaceNode(replacer, node[id], idPath, i + 1)
  };
};

const replaceNodeById = (node, id, visitor) => {
  // Pass array of the id's parts instead of working on the string
  // directly - easy way to handle multi-number ID parts e.g. 3.1.15.32
  return replaceNode(visitor, node, id.split("."), 1);
};

const expandedNode = () => ({});
const unexpandedNode = () => undefined;

const toggleNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode =>
    oldNode ? unexpandedNode() : expandedNode()
  );
const expandNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode => expandedNode());

class Menu extends Component {
  constructor(props) {
    super(props);
    this.state = {
      menuItems: [],
      openMenus: {},
      checkedMenus: {}
    };
    this.handleMenuToggle = this.handleMenuToggle.bind(this);
    this.handleChecked = this.handleChecked.bind(this);
  }

  render() {
    const { menuItems, openMenus, checkedMenus } = this.state;

    return (
      <MenuItemContainer
        openMenus={openMenus}
        menuItems={menuItems}
        onMenuToggle={this.handleMenuToggle}
        checkedMenus={checkedMenus}
        onChecked={this.handleChecked}
      />
    );
  }

  componentDidMount() {
    const { initialOpenMenuId, initialCheckedMenuIds } = this.props;

    loadMenu().then(menuItems => {
      const initialMenuState = {};
      this.setState({
        menuItems,
        openMenus: expandNodeById(initialMenuState, initialOpenMenuId),
        checkedMenus: initialCheckedMenuIds.reduce(
          (acc, val) => ({ ...acc, [val]: true }),
          {}
        )
      });
    });
  }

  handleMenuToggle(toggledId) {
    this.setState(({ openMenus }) => ({
      openMenus: toggleNodeById(openMenus, toggledId)
    }));
  }

  handleChecked(toggledId) {
    this.setState(({ checkedMenus }) => ({
      checkedMenus: {
        ...checkedMenus,
        [toggledId]: checkedMenus[toggledId] ? unexpandedNode() : expandedNode()
      }
    }));
  }
}

function MenuItemContainer({
  openMenus,
  onMenuToggle,
  checkedMenus,
  onChecked,
  menuItems = []
}) {
  if (!menuItems.length) return null;

  const renderMenuItem = menuItem => (
    <li key={menuItem.id}>
      <MenuItem
        openMenus={openMenus}
        onMenuToggle={onMenuToggle}
        checkedMenus={checkedMenus}
        onChecked={onChecked}
        {...menuItem}
      />
    </li>
  );

  return <ul>{menuItems.map(renderMenuItem)}</ul>;
}

class MenuItem extends Component {
  constructor(props) {
    super(props);
    this.handleToggle = this.handleToggle.bind(this);
    this.handleChecked = this.handleChecked.bind(this);
  }

  render() {
    const {
      children,
      name,
      id,
      openMenus,
      onMenuToggle,
      checkedMenus,
      onChecked
    } = this.props;

    const isLastChild = !children;
    return (
      <Fragment>
        <Button onClick={isLastChild ? this.handleChecked : this.handleToggle}>
          {name}
        </Button>
        {isLastChild && (
          <Input
            addon
            type="checkbox"
            onChange={this.handleChecked}
            checked={!!checkedMenus[id]}
            value={id}
          />
        )}

        <Collapse isOpen={openMenus ? !!openMenus[id] : false}>
          <MenuItemContainer
            menuItems={children}
            // Pass down child menus' state
            openMenus={openMenus && openMenus[id]}
            onMenuToggle={onMenuToggle}
            checkedMenus={checkedMenus}
            onChecked={onChecked}
          />
        </Collapse>
      </Fragment>
    );
  }

  handleToggle() {
    this.props.onMenuToggle(this.props.id);
  }

  handleChecked() {
    this.props.onChecked(this.props.id);
  }
}

ReactDOM.render(
  <Menu initialOpenMenuId="3.1.1.1" initialCheckedMenuIds={["3.1.1.1.1"]} />,
  document.getElementById("root")
);

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<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.4.1/css/bootstrap.min.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/reactstrap/8.4.1/reactstrap.min.js"></script>

<div id="root"></div>

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演练

在开始之前，我必须说我已经冒昧地更改了一些代码以使用现代 JavaScript 功能，例如对象解构、数组解构、剩余值和默认值。

创建国家

所以。由于菜单项的 ID 是由点分隔的数字，因此我们可以在构造状态时利用这一点。状态本质上是一个树状结构，每个子菜单都是其父级的子菜单，并且叶节点（“最后一个菜单”或“最深的菜单”）具有值（{}如果展开或undefined不展开）。以下是菜单初始状态的构造方式：

<Menu initialOpenMenuId="3.1.1.1" initialCheckedMenuIds={["3.1.1.1.1"]} />

// ...

loadMenu().then(menuItems => {
  const initialMenuState = {};
  this.setState({
    menuItems,
    openMenus: expandNodeById(initialMenuState, initialOpenMenuId),
    checkedMenus: initialCheckedMenuIds.reduce(
      (acc, val) => ({ ...acc, [val]: true }),
      {}
    )
  });
});

// ...

const expandedNode = () => ({});
const unexpandedNode = () => undefined;

const toggleNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode =>
    oldNode ? unexpandedNode() : expandedNode()
  );
const expandNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode => expandedNode());

const replaceNodeById = (node, id, visitor) => {
  // Pass array of the id's parts instead of working on the string
  // directly - easy way to handle multi-number ID parts e.g. 3.1.15.32
  return replaceNode(visitor, node, id.split("."), 1);
};

const replaceNode = (replacer, node, idPath, i) => {
  if (i <= idPath.length && !node) {
    // Not at target node yet, create nodes in between
    node = {};
  }
  if (i > idPath.length) {
    // Reached target node
    return replacer(node);
  }

  // Construct ID that matches this depth - depth meaning
  // the amount of dots in between the ID
  const id = idPath.slice(0, i).join(".");
  return {
    ...node,
    // Recurse
    [id]: replaceNode(replacer, node[id], idPath, i + 1)
  };
};

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让我们一点一点地拆开这个问题。

const expandedNode = () => ({});
const unexpandedNode = () => undefined;

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这些只是我们定义的便利函数，因此我们可以轻松更改用于表示展开和未展开节点的值。{}与仅使用文字或undefined在代码中相比，它还使代码更具可读性。展开和未展开的值也可以是true和false，重要的是展开的节点为真，未展开的节点为假。稍后会详细介绍。

const toggleNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode =>
    oldNode ? unexpandedNode() : expandedNode()
  );
const expandNodeById = (node, id) =>
  replaceNodeById(node, id, oldNode => expandedNode());

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这些功能让我们可以在菜单状态下切换或展开特定菜单。第一个参数是菜单状态本身，第二个参数是菜单的字符串 ID（例如"3.1.1.1.1"），第三个参数是执行替换的函数。将此视为您传递给的函数.map()。替换器功能与实际的递归树迭代分开，以便您以后可以轻松实现更多功能 - 例如，如果您希望取消某些特定菜单的展开，您只需传入一个返回的函数即可unexpandedNode()。

const replaceNodeById = (node, id, visitor) => {
  // Pass array of the id's parts instead of working on the string
  // directly - easy way to handle multi-number ID parts e.g. 3.1.15.32
  return replaceNode(visitor, node, id.split("."), 1);
};

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前两个函数使用此函数来提供更清晰的界面。ID 在此被点 ( .) 分割，这为我们提供了 ID 部分的数组。next 函数对这个数组进行操作，而不是直接对 ID 字符串进行操作，因为这样我们就不需要做任何.indexOf('.')恶作剧了。

const replaceNode = (replacer, node, idPath, i) => {
  if (i <= idPath.length && !node) {
    // Not at target node yet, create nodes in between
    node = {};
  }
  if (i > idPath.length) {
    // Reached target node
    return replacer(node);
  }

  // Construct ID that matches this depth - depth meaning
  // the amount of dots in between the ID
  const id = idPath.slice(0, i).join(".");
  return {
    ...node,
    // Recurse
    [id]: replaceNode(replacer, node[id], idPath, i + 1)
  };
};

Run Code Online (Sandbox Code Playgroud)

功能replaceNode是问题的核心。它是一个递归函数，从旧的菜单树生成新的树，用提供的替换函数替换旧的目标节点。如果树缺少中间的部分，例如当树是{}但我们想要替换节点时3.1.1.1，它会在中间创建父节点。mkdir -p如果您熟悉该命令，就有点像。

这就是菜单状态。复选框状态 ( checkedMenus) 基本上只是一个索引，键是 ID 和true选中某项时的值。此状态不是递归的，因为不需要取消检查或递归检查它们。如果您决定要显示一个指示符，表明此菜单项下的某些内容已被选中，一个简单的解决方案是将复选框状态更改为像菜单状态一样的递归状态。

渲染树

该<Menu>组件将状态传递给<MenuItemContainer>，从而呈现<MenuItem>s。

function MenuItemContainer({
  openMenus,
  onMenuToggle,
  checkedMenus,
  onChecked,
  menuItems = []
}) {
  if (!menuItems.length) return null;

  const renderMenuItem = menuItem => (
    <li key={menuItem.id}>
      <MenuItem
        openMenus={openMenus}
        onMenuToggle={onMenuToggle}
        checkedMenus={checkedMenus}
        onChecked={onChecked}
        {...menuItem}
      />
    </li>
  );

  return <ul>{menuItems.map(renderMenuItem)}</ul>

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