beforeHandleMessage

Introduction

The beforeHandleMessage hook is called when a message was received by the server, directly before handling / applying it. The hook can be used to reject a message (e.g. if the authentication token has expired), or even to check the update message and reject / accept it based on custom rules. If you throw an error in the hook, the connection will be closed. You can return a custom code / reason by throwing an error that implements CloseEvent (see example below).

Hook payload

The data passed to the beforeHandleMessage hook has the following attributes:

import { IncomingHttpHeaders } from 'http'
import { URLSearchParams } from 'url'
import { Doc } from 'yjs'
import { CloseEvent } from '@hocuspocus/common'

const data = {
  clientsCount: number,
  context: any,
  document: Doc,
  documentName: string,
  instance: Hocuspocus,
  requestHeaders: IncomingHttpHeaders,
  requestParameters: URLSearchParams,
  update: Uint8Array,
  socketId: string,
}

Context contains the data provided in former onConnect hooks.

Example

import { debounce } from 'debounce'
import { Server } from '@hocuspocus/server'
import { TiptapTransformer } from '@hocuspocus/transformer'
import { writeFile } from 'fs'

let debounced

const server = Server.configure({
  beforeHandleMessage(data) {
    if (data.context.tokenExpiresAt <= new Date()) {
      const error: CloseEvent = {
        reason: 'Token expired',
      }

      throw error
    }
  },
})

server.listen()