Reusing MongoDB connection in node

Question

This is the error I get: [Error: db object already connecting, open cannot be called multiple times]. I have a global mongo object in this vows test.

mongo = new mongo.Db(config.api.apiTest, new mongo.Server('localhost', 27017, {}), {native_parser: off, safe: true})

When I try to open it the second time I get this error.

So even though I'm using db.close() the first time it doesn't seem to close. Is there another way of re-using the connection?

.addBatch(
  "Redis - ":
    "Standard account - ":
      topic: ->

        # .
        redisClient.del "#{ accountId }:900"

        mongo.open (error, db) =>
          secondDb = db.db config.api.accountTest

          secondDb.collection 'accounts', (error, accountsColl) =>
            accountsColl.update {'accountId': ObjectID(accountId)}, { "$unset": {'permission': ''}}, (error, records) =>
              console.log "Unset? " + records
              db.close()
          db.close()


        inventory = nock('http://inventory.honshuu.vgrnt:80')
            .get("/devices/?accountId=#{ accountId }&userId=#{ userId }")
            .reply(200, 'OK')

        httpRequest.get 'http://127.0.0.1:18091/inventory/devices/?token=testtoken', @callback
        return

      "Ratelimit is applied correctly":
        (error, response, body) ->
          accountLimit = response.headers['x-ratelimit-limit']
          assert.equal response.headers['x-ratelimit-remaining'], 240-1
          assert.equal response.headers['x-ratelimit-reset'], 900

    "account":
      topic: ->
        # Need to fetch permission in db.
        # redisClient.del "permission-#{ accountId }", (error, result) =>
        #   console.log "removes"
        #   console.log result

        inventory = nock('http://inventory.honshuu.vgrnt:80')
          .get("/devices/?accountId=#{ accountId }&userId=#{ userId }")
          .reply(200, 'OK')

        mongo.open (error, db) =>
          secondDb = db.db config.api.accountTest
          console.log secondDb

          secondDb.collection 'accounts', (error, accountsColl) =>
            accountsColl.update {'accountId': ObjectID(accountId)}, { 'permission': 1000}, (error, records) =>
              console.log "updated? " + records
              httpRequest.get 'http://127.0.0.1:18091/inventory/devices/?token=testtoken', @callback
              return

        return

      "account has more rate tokens":
        (error, response, body) ->
          console.log response
          console.log error
          # accountLimit = response.headers['x-ratelimit-limit']
          # assert.equal response.headers['x-ratelimit-remaining'], 1000-1
          # assert.equal response.headers['x-ratelimit-reset'], 900
          # assert.equal response.headers['x-ratelimit-limit'], 1000
)

Answer 1

Just like most things in node, db.close is asynchronous and accepts a callback. You'll need to pass the callback or promisify it and return a promise. Your next connect call should only be done when you're positive the db connection has closed, and you'll only know that by handling the callback.

db.close(function (err) {
  if (err) return console.error('OH NOES, AN ERROR:', err);
  console.log('SUCCESS!');
  // db is now closed, do whatevs
});