Thread: Unable to connect to the database: TypeError: net.Socket is not a constructor

On 4/20/20 10:50 AM, Marco Ippolito wrote:
> I'm trying to connect to a postgres database (Postgresql-11) within my 
> nodejs-vue.js app, but in console I'm getting this error:
> 
>      [HMR] Waiting for update signal from WDS...
>      pg.js?c8c2:27 Unable to connect to the database: TypeError: 
> net.Socket is not a constructor

>      Environment Info:
> 
>        System:
>          OS: Linux 5.3 Ubuntu 18.04.4 LTS (Bionic Beaver)
>          CPU: (8) x64 Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
>        Binaries:
>          Node: 12.15.0 - ~/.nvm/versions/node/v12.15.0/bin/node
>          Yarn: 1.22.4 - ~/.nvm/versions/node/v12.15.0/bin/yarn
>          npm: 6.14.4 - ~/.nvm/versions/node/v12.15.0/bin/npm
>        Browsers:
>          Chrome: 81.0.4044.92
>          Firefox: 75.0
>        npmGlobalPackages:
>          @vue/cli: 4.2.3
> 
> So... how to solve the problem?

 From what I can gather the issue is that the code is running in the 
context of the browser and net.Socket is not supported there. It seems 
that the fix is to run the database code in node.js and pass the data 
from there to vue.js. Honestly, this whole reactive code thing is still 
something I'm wrapping my head around. I did find some tutorials 
searching on 'node.js vue.js Sequelize postgresql'. Most seemed to use 
express.js as the glue between node and vue.


> Looking forward to your kind help.
> Marco


-- 
Adrian Klaver
adrian.klaver@aklaver.com

On 4/20/20 11:29 AM, Marco Ippolito wrote:
> 
> 
> Il giorno lun 20 apr 2020 alle ore 20:11 Adrian Klaver 
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> ha scritto:
> 
>     On 4/20/20 10:50 AM, Marco Ippolito wrote:
>      > I'm trying to connect to a postgres database (Postgresql-11)
>     within my
>      > nodejs-vue.js app, but in console I'm getting this error:
>      >
>      >      [HMR] Waiting for update signal from WDS...
>      >      pg.js?c8c2:27 Unable to connect to the database: TypeError:
>      > net.Socket is not a constructor
> 
>      >      Environment Info:
>      >
>      >        System:
>      >          OS: Linux 5.3 Ubuntu 18.04.4 LTS (Bionic Beaver)
>      >          CPU: (8) x64 Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
>      >        Binaries:
>      >          Node: 12.15.0 - ~/.nvm/versions/node/v12.15.0/bin/node
>      >          Yarn: 1.22.4 - ~/.nvm/versions/node/v12.15.0/bin/yarn
>      >          npm: 6.14.4 - ~/.nvm/versions/node/v12.15.0/bin/npm
>      >        Browsers:
>      >          Chrome: 81.0.4044.92
>      >          Firefox: 75.0
>      >        npmGlobalPackages:
>      >          @vue/cli: 4.2.3
>      >
>      > So... how to solve the problem?
> 
>       From what I can gather the issue is that the code is running in the
>     context of the browser and net.Socket is not supported there. It seems
>     that the fix is to run the database code in node.js and pass the data
>     from there to vue.js. Honestly, this whole reactive code thing is still
>     something I'm wrapping my head around. I did find some tutorials
>     searching on 'node.js vue.js Sequelize postgresql'. Most seemed to use
>     express.js as the glue between node and vue.
> 
> 
> Thank you Adrian for your very kind response.
> express.js is the server framework for node.js
> So...two questions come in mind:
>    am I obliged to use express.js as glue between node and vue, if I 
> already use nginx as web server?
>    And if I'm obliged to use another web server apart from nginx to glue 
> node and vue, would it be possible to use a golang web-server,
>    which could be a further complication but would have its own positive 
> sides?

I have no idea, this is not something I normally deal with. I would 
guess you will get better answers from a node.js forum.

> 
> Marco
> 
> 
> 
>      > Looking forward to your kind help.
>      > Marco
> 
> 
>     -- 
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com

Marco Ippolito <ippolito.marco@gmail.com> writes:

> I'm trying to connect to a postgres database (Postgresql-11) within my
> nodejs-vue.js app, but in console I'm getting this error:
>
>     [HMR] Waiting for update signal from WDS...
>     pg.js?c8c2:27 Unable to connect to the database: TypeError: net.Socket
> is not a constructor
>         at new Connection
> (webpack-internal:///./node_modules/pg/lib/connection.js:22:34)
>         at new Client
> (webpack-internal:///./node_modules/pg/lib/client.js:55:37)
>         at Promise.tap.query
> (webpack-internal:///./node_modules/sequelize/lib/dialects/postgres
>     /connection-manager.js:124:26)
>         at ConnectionManager.connect
> (webpack-internal:///./node_modules/sequelize/lib/dialects
>     /postgres/connection-manager.js:121:12)
>         at eval
> (webpack-internal:///./node_modules/sequelize/lib/dialects/abstract/connection-
>     manager.js:318:50)
>     From previous event:
>         at ConnectionManager._connect
> (webpack-internal:///./node_modules/sequelize/lib/dialects
>     /abstract/connection-manager.js:318:8)
>         at ConnectionManager.getConnection
> (webpack-internal:///./node_modules/sequelize/lib/dialects
>     /abstract/connection-manager.js:254:46)
>         at eval
> (webpack-internal:///./node_modules/sequelize/lib/sequelize.js:640:36)
>     From previous event:
>         at eval
> (webpack-internal:///./node_modules/sequelize/lib/sequelize.js:631:53)
>         at eval
> (webpack-internal:///./node_modules/retry-as-promised/index.js:70:21)
>         at new Promise (<anonymous>)
>         at retryAsPromised
> (webpack-internal:///./node_modules/retry-as-promised/index.js:60:10)
>         at eval
> (webpack-internal:///./node_modules/sequelize/lib/sequelize.js:631:30)
>     From previous event:
>         at Sequelize.query
> (webpack-internal:///./node_modules/sequelize/lib/sequelize.js:580:23)
>         at Sequelize.authenticate
> (webpack-internal:///./node_modules/sequelize/lib/sequelize.js:892:17)
>         at eval (webpack-internal:///./src/plugins/db/pg.js:23:11)
>         at Object../src/plugins/db/pg.js (https://ggc.world/js/app.js:1128:1
> )
>         at __webpack_require__ (https://ggc.world/js/app.js:785:30)
>         at fn (https://ggc.world/js/app.js:151:20)
>         at eval (webpack-internal:///./src/main.js:16:72)
>         at Module../src/main.js (https://ggc.world/js/app.js:1083:1)
>         at __webpack_require__ (https://ggc.world/js/app.js:785:30)
>         at fn (https://ggc.world/js/app.js:151:20)
>         at Object.1 (https://ggc.world/js/app.js:1141:18)
>         at __webpack_require__ (https://ggc.world/js/app.js:785:30)
>         at checkDeferredModules (https://ggc.world/js/app.js:46:23)
>         at https://ggc.world/js/app.js:861:18
>         at https://ggc.world/js/app.js:864:10
>
>  In /src/main.js :
>
>     import '@/plugins/db/pg';
>
>     (base) /src/plugins/db$ ls -lah
>     total 28K
>     drwxr-xr-x 6 marco marco 4,0K apr 20 15:42 .
>     drwxr-xr-x 3 marco marco 4,0K apr 20 15:41 ..
>     drwxr-xr-x 2 marco marco 4,0K apr 20 17:20 config
>     drwxr-xr-x 2 marco marco 4,0K apr 20 15:48 migrations
>     drwxr-xr-x 2 marco marco 4,0K apr 20 15:48 models
>     -rw-r--r-- 1 marco marco  819 apr 20 08:53 pg.js
>     drwxr-xr-x 2 marco marco 4,0K apr 20 17:21 seeders
>
>
> nano pg.js
>
>     const { Pool } = require('pg');
>     const { Sequelize } = require('sequelize');
>     const pool = new Pool();
>     const sequelize = new Sequelize('pusers', 'postgres', 'pwd', {
>       host: 'localhost',
>       dialect: 'postgres',
>       pool: {
>         max: 5,
>         min: 0,
>         acquire: 30000,
>         idle: 10000
>       }
>     });
>     sequelize
>       .authenticate()
>       .then(() => {
>         console.log('Connection has been established successfully.');
>       })
>       .catch(err => {
>         console.log('Unable to connect to the database:', err);
>       });
>
>     module.exports = {
>       query: (text, params, callback) => {
>         return pool.query(text, params, callback);
>       },
>     }
>
> Populated the sample database with a row:
>
>     pusers=# SELECT schemaname,relname,n_live_tup
>     pusers-#   FROM pg_stat_user_tables
>     pusers-#   ORDER BY n_live_tup DESC;
>      schemaname |    relname    | n_live_tup
>     ------------+---------------+------------
>      public     | pusers        |          1
>      public     | SequelizeMeta |          1
>     (2 rows)
>
> I read here:
> https://stackoverflow.com/questions/40599069/node-js-net-socket-is-not-a-constructor
> that
> "there are no plain TCP sockets in the browser, so that is why trying to
> use `net.Socket` in the browser (via webpack, browserify, etc.) won't work"
>
>     Environment Info:
>
>       System:
>         OS: Linux 5.3 Ubuntu 18.04.4 LTS (Bionic Beaver)
>         CPU: (8) x64 Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
>       Binaries:
>         Node: 12.15.0 - ~/.nvm/versions/node/v12.15.0/bin/node
>         Yarn: 1.22.4 - ~/.nvm/versions/node/v12.15.0/bin/yarn
>         npm: 6.14.4 - ~/.nvm/versions/node/v12.15.0/bin/npm
>       Browsers:
>         Chrome: 81.0.4044.92
>         Firefox: 75.0
>       npmGlobalPackages:
>         @vue/cli: 4.2.3
>
> So... how to solve the problem?
> Looking forward to your kind help.
> Marco

This has nothing to do with postgres. This is a purely Javascript issue
combined with differences between the browser Javascript API and node
javascript API.

Bottom line - if your trying to connect directly to a PG database from
within Javascript code running inside the browser, it won't work. The
browser does not have the 'net' library. You can only do this from
within node.js. Likewise, references to express are also red hearings -
you don't have a web server inside the browser either. If your not
trying to develop inside the browser but are in fact developing at the
node.js level, then you don't need webpack.

I think what you really need to do is step back and look closer at your
architecture. Typically, you would put all your database interaction
stuff in the web server using node.js. A common design pattern would be
to use one of the node.js web servers, like express (but there are
others) and have something like nginx as a proxy server in front of it.
You would then wrap your database interaction in a node.js API which you
would then call from your client browser using http/https or web
sockets. 

-- 
Tim Cross