我已经安装了mongodb，可以通过shell连接，现在我正在尝试安装mongo express，安装成功，我在config.js中复制了config.default.js文件，但它无法连接到mongo。从错误中可以看出，它无法检索主机名
(node:3085) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
(Use `node --trace-deprecation ...` to show where the warning was created)
Could not connect to database at index "0"
(node:3085) UnhandledPromiseRejectionWarning: MongoNetworkError: failed to connect to server [undefined:27017] on first connect [Error: getaddrinfo ENOTFOUND undefined
at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:67:26) {
name: 'MongoNetworkError'
}]
at Pool.<anonymous> (/Users/name/.config/yarn/global/node_modules/mongodb/lib/core/topologies/server.js:438:11)
at Pool.emit (events.js:315:20)
at /Users/name/.config/yarn/global/node_modules/mongodb/lib/core/connection/pool.js:562:14
at /Users/name/.config/yarn/global/node_modules/mongodb/lib/core/connection/pool.js:995:11
at /Users/name/.config/yarn/global/node_modules/mongodb/lib/core/connection/connect.js:32:7
at callback (/Users/name/.config/yarn/global/node_modules/mongodb/lib/core/connection/connect.js:280:5)
at Socket.<anonymous> (/Users/name/.config/yarn/global/node_modules/mongodb/lib/core/connection/connect.js:310:7)
at Object.onceWrapper (events.js:422:26)
at Socket.emit (events.js:315:20)
at emitErrorNT (internal/streams/destroy.js:106:8)
at emitErrorCloseNT (internal/streams/destroy.js:74:3)
at processTicksAndRejections (internal/process/task_queues.js:80:21)
(node:3085) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:3085) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
我也有同样的错误
强制连接URL为我修复了它：
mongo-express --url "mongodb://localhost:27017" --admin
(--admin选项允许列出所有数据库(