element-admin 动态路由

element-admin 是一个基于 Vue.js 和 Element UI 的后台管理系统框架，它支持动态路由配置。

动态路由是指在用户登录后，根据用户的权限动态生成路由。这样可以保证用户只能访问他有权限访问的页面，提高系统的安全性。

在 element-admin 中，动态路由是通过在路由配置文件中定义一个 routes 数组来实现的。该数组中的路由对象可以通过后台接口获取，然后根据用户的权限进行筛选和过滤。

具体实现步骤如下：

1. 在路由配置文件中定义一个 routes 数组，并将该数组赋值给 router 的 routes 属性。

import Vue from 'vue'
import Router from 'vue-router'

Vue.use(Router)

export const constantRoutes = [
  {
    path: '/',
    component: Layout,
    redirect: '/dashboard',
    children: [
      {
        path: 'dashboard',
        component: () => import('@/views/dashboard/index'),
        name: 'Dashboard',
        meta: { title: 'Dashboard', icon: 'dashboard' }
      }
    ]
  },
  {
    path: '/login',
    component: () => import('@/views/login/index'),
    hidden: true
  }
]

const createRouter = () => new Router({
  mode: 'history', // require service support
  scrollBehavior: () => ({ y: 0 }),
  routes: constantRoutes
})

const router = createRouter()

export function resetRouter() {
  const newRouter = createRouter()
  router.matcher = newRouter.matcher // reset router
}

export default router

2. 在路由配置文件中定义一个 asyncRoutes 数组，用于存放动态路由。

export const asyncRoutes = [
  {
    path: '/permission',
    component: Layout,
    redirect: '/permission/index',
    alwaysShow: true, // will always show the root menu
    name: 'Permission',
    meta: {
      title: 'Permission',
      icon: 'lock',
      roles: ['admin', 'editor'] // you can set roles in root nav
    },
    children: [
      {
        path: 'index',
        component: () => import('@/views/permission/index'),
        name: 'PagePermission',
        meta: {
          title: 'Page Permission',
          roles: ['admin'] // or you can only set roles in sub nav
        }
      },
      {
        path: 'directive',
        component: () => import('@/views/permission/directive'),
        name: 'DirectivePermission',
        meta: {
          title: 'Directive Permission'
          // if do not set roles, means: this page does not require permission
        }
      }
    ]
  }
]

3. 在用户登录成功后，根据用户的权限从后台接口获取符合权限的路由，并将其添加到 routes 数组中。

import { constantRoutes, asyncRoutes } from '@/router'

/**
 * Use meta.role to determine if the current user has permission
 * @param roles
 * @param route
 */
function hasPermission(roles, route) {
  if (route.meta && route.meta.roles) {
    return roles.some(role => route.meta.roles.includes(role))
  } else {
    return true
  }
}

/**
 * Filter asynchronous routing tables by recursion
 * @param routes asyncRoutes
 * @param roles
 */
export function filterAsyncRoutes(routes, roles) {
  const res = []

  routes.forEach(route => {
    const tmp = { ...route }
    if (hasPermission(roles, tmp)) {
      if (tmp.children) {
        tmp.children = filterAsyncRoutes(tmp.children, roles)
      }
      res.push(tmp)
    }
  })

  return res
}

const state = {
  routes: [],
  addRoutes: []
}

const mutations = {
  SET_ROUTES: (state, routes) => {
    state.addRoutes = routes
    state.routes = constantRoutes.concat(routes)
  }
}

const actions = {
  generateRoutes({ commit }, roles) {
    return new Promise(resolve => {
      let accessedRoutes
      if (roles.includes('admin')) {
        accessedRoutes = asyncRoutes || []
      } else {
        accessedRoutes = filterAsyncRoutes(asyncRoutes, roles)
      }
      commit('SET_ROUTES', accessedRoutes)
      resolve(accessedRoutes)
    })
  }
}

export default {
  namespaced: true,
  state,
  mutations,
  actions
}

4. 在路由导航守卫中判断用户访问的页面是否在路由中存在，如果不存在则跳转到 404 页面。

import router from './router'
import store from './store'
import { Message } from 'element-ui'
import NProgress from 'nprogress' // progress bar
import 'nprogress/nprogress.css' // progress bar style
import { getToken } from '@/utils/auth' // get token from cookie
import getPageTitle from '@/utils/get-page-title'

NProgress.configure({ showSpinner: false }) // NProgress Configuration

const whiteList = ['/login', '/auth-redirect'] // no redirect whitelist

router.beforeEach(async(to, from, next) => {
  // start progress bar
  NProgress.start()

  // set page title
  document.title = getPageTitle(to.meta.title)

  // determine whether the user has logged in
  const hasToken = getToken()

  if (hasToken) {
    if (to.path === '/login') {
      // if is logged in, redirect to the home page
      next({ path: '/' })
      NProgress.done()
    } else {
      // determine whether the user has obtained his permission roles through getInfo
      const hasRoles = store.getters.roles && store.getters.roles.length > 0
      if (hasRoles) {
        next()
      } else {
        try {
          // get user info
          // note: roles must be a object array! such as: ['admin'] or ,['developer','editor']
          const { roles } = await store.dispatch('user/getInfo')

          // generate accessible routes map based on roles
          const accessRoutes = await store.dispatch('permission/generateRoutes', roles)

          // dynamically add accessible routes
          router.addRoutes(accessRoutes)

          // hack method to ensure that addRoutes is complete
          // set the replace: true, so the navigation will not leave a history record
          next({ ...to, replace: true })
        } catch (error) {
          // remove token and go to login page to re-login
          await store.dispatch('user/resetToken')
          Message.error(error || 'Has Error')
          next(`/login?redirect=${to.path}`)
          NProgress.done()
        }
      }
    }
  } else {
    /* has no token*/

    if (whiteList.indexOf(to.path) !== -1) {
      // in the free login whitelist, go directly
      next()
    } else {
      // other pages that do not have permission to access are redirected to the login page.
      next(`/login?redirect=${to.path}`)
      NProgress.done()
    }
  }
})

router.afterEach(() => {
  // finish progress bar
  NProgress.done()
})