Couchase Node Js sdk connection-CodePudding

I am trying to connect my couchbase server but i am getting warning msg when i an trying to create a connection instance on app.js on my express.js app.

Here is the app.js

const express = require('express');
const bodyParser = require('body-parser');
const couchbase = require('couchbase');

const app = express();
const userRoutes = require('./routes/route');


app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));

//COUCHBASE CONNECTION
const cluster = couchbase.connect('couchbase://localhost', {username: 'admin', password: '5121451214'},(err,cluster) => { 
    const bucket =  cluster.bucket('test_data_bucket');
    module.exports.bucket = bucket;
}); 



app.use('/',userRoutes);

app.listen(process.env.port || 3000);

console.log('Web Server is listening at port '  (process.env.port || 3000));

Here is my AutherModel

const N1qlQuery = require('couchbase').N1qlQuery;
const data_bucket = require('../app').bucket;


function AuthorModel (){}

AuthorModel.getAll = function (callback)
{
    data_bucket.get('invoice_32212100000218', (err, res) => {
        if(error)
        {
            return callback(error,null);
        }

        callback(null,res);
    });
}


module.exports.AuthorModel = AuthorModel;

when i run node app.js getting this error

node:2410417) Warning: Accessing non-existent property 'bucket' of module exports inside circular dependency
(Use `node --trace-warnings ...` to show where the warning was created)

//RESULT AFTER CHANGES

connection.js

const couchbase = require('couchbase');

//COUCHBASE CONNECTION
couchbase.connect('couchbase://localhost', {username: 'admin', password: '5121451214'},(err,cluster) => {
  const bucket =  cluster.bucket('test_data_bucket');
  const defautScope = bucket.scope('_default');
  const defaultCollection = defautScope.collection('_default');

  module.exports.bucket = bucket;
  module.exports.cluster = cluster;
  module.exports.defaultCollection = defaultCollection;
});

author.js model

 const connection = require('../config/connection');
    
    const data_bucket = connection.bucket;
    const data_cluster = connection.cluster;
    const data_collection = connection.defaultCollection;
    
    
    module.exports = {
        getUsers  ()
        {
            const data = data_collection.get('invoice_32212100000218', (err, res) => {
                console.log(res);
            });
    
            return 'Hello from express';
        }
     }

GETTING THIS ERROR

TypeError: Cannot read properties of undefined (reading 'get')

CodePudding user response：

The circular dependency warning is likely because you are exporting the bucket from app.js, requiring it in your model, which is also likely included somewhere in app.js, forming a circular dependency.

To fix this, I would suggest moving the connection code into a separate file, so that you can require it wherever needed in your models and routes.

Important note: If you are using the Node.js SDK version 3.0 or above, you'll need to call .get() on a collection level object, rather than on the bucket. You can easily just export the collection you need from your connection code. See the following example of a connection file, which uses default scope and collection:

// connection.js
const couchbase = require('couchbase')

//COUCHBASE CONNECTION
const cluster = couchbase.connect('couchbase://localhost', {username: 'admin', password: '5121451214'},(err,cluster) => {
  const bucket =  cluster.bucket('test_data_bucket');
  const defautScope = bucket.scope('_default');
  const defaultCollection = defautScope.collection('_default')

  module.exports.bucket = bucket;
  module.exports.cluster = cluster;
  module.exports.defaultCollection = defaultCollection;
});

You can then easily require connection.js in your model and obtain bucket, cluster, or collection level objects as needed:

const connection = require('../connection');

const data_bucket = connection.bucket;
const data_cluster = connection.cluster;
const data_collection = connection.defaultCollection;