Undefined db connection with knex

问题

I am executing the following script, node acl.js:

acl.js

require('dotenv').config()

const _ = require('lodash');
const buckets = require('./buckets');
const knex = require('../src/config/db'); //HERE I am getting the ERROR

var downSql = 'DROP TABLE IF EXISTS "{{prefix}}{{meta}}";'+
    'DROP TABLE IF EXISTS "{{prefix}}{{resources}}";'+
    'DROP TABLE IF EXISTS "{{prefix}}{{parents}}";'+
    'DROP TABLE IF EXISTS "{{prefix}}{{users}}";'+
    'DROP TABLE IF EXISTS "{{prefix}}{{roles}}";'+
    'DROP TABLE IF EXISTS "{{prefix}}{{permissions}}";';
var upSql = 'CREATE TABLE "{{prefix}}{{meta}}" (key TEXT NOT NULL PRIMARY KEY, value TEXT[][] NOT NULL);'+
    'INSERT INTO "{{prefix}}{{meta}}" VALUES (\'users\', \'{}\');'+
    'INSERT INTO "{{prefix}}{{meta}}" VALUES (\'roles\', \'{}\');'+
    'CREATE TABLE "{{prefix}}{{resources}}" (key TEXT NOT NULL PRIMARY KEY, value TEXT[][] NOT NULL);'+
    'CREATE TABLE "{{prefix}}{{parents}}" (key TEXT NOT NULL PRIMARY KEY, value TEXT[][] NOT NULL);'+
    'CREATE TABLE "{{prefix}}{{roles}}" (key TEXT NOT NULL PRIMARY KEY, value TEXT[][] NOT NULL);'+
    'CREATE TABLE "{{prefix}}{{users}}" (key TEXT NOT NULL PRIMARY KEY, value TEXT[][] NOT NULL);'+
    'CREATE TABLE "{{prefix}}{{permissions}}" (key TEXT NOT NULL PRIMARY KEY, value JSON NOT NULL);';

function tmpl(str, ctx) {
    var n = 1;
    var sql = str.replace(/{{(\w+)}}/g, function(match, cap1) {
        return ctx[cap1] || match;
    });
    return sql.replace(/\?/g, function() { return '$' + n++; });
}

function createTables(callback) {
    var prefix = ''
    var bucketNames = buckets(args[8])

    if (!prefix) prefix = 'acl_';

    knex.raw(tmpl(downSql+upSql, {
            'meta': bucketNames.meta,
            'parents': bucketNames.parents,
            'permissions': bucketNames.permissions,
            'prefix': prefix,
            'resources': bucketNames.resources,
            'roles': bucketNames.roles,
            'users': bucketNames.users
        }))
        .then(function() {
            if (!_.isUndefined(callback)) {
                callback(null, db);
            }
        })
    ;
}

createTables()

buckets.js

'use strict';

var _ = require('lodash');

var buckets = function(options){
    return _.extend({
        meta: 'meta',
        parents: 'parents',
        permissions: 'permissions',
        resources: 'resources',
        roles: 'roles',
        users: 'users'
    }, options);
};

exports = module.exports = buckets;

When I run node acl.js I get the following error:

> node acl.js
{ development:
   { client: undefined,
     connection: { user: undefined, password: undefined, database: undefined } } }
undefined
C:\Users\admin\Desktop\Coding Projects\learning_npm_node_acl\node_modules\knex\lib\index.js:49
  if (arguments.length === 0 || !config.client && !config.dialect) {
                                       ^

TypeError: Cannot read property 'client' of undefined
    at Knex (C:\Users\admin\Desktop\Coding Projects\learning_npm_node_acl\node_modules\knex\lib\index.js:49:40)
    at Object.<anonymous> (C:\Users\admin\Desktop\Coding Projects\learning_npm_node_acl\src\config\db.js:8:29)
    at Module._compile (module.js:573:30)
    at Object.Module._extensions..js (module.js:584:10)
    at Module.load (module.js:507:32)
    at tryModuleLoad (module.js:470:12)
    at Function.Module._load (module.js:462:3)
    at Module.require (module.js:517:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (C:\Users\admin\Desktop\Coding Projects\learning_npm_node_acl\node_acl\acl.js:5:14)
    at Module._compile (module.js:573:30)
    at Object.Module._extensions..js (module.js:584:10)
    at Module.load (module.js:507:32)
    at tryModuleLoad (module.js:470:12)
    at Function.Module._load (module.js:462:3)
    at Function.Module.runMain (module.js:609:10)

The error comes from the line const knex = require('../src/config/db'); in my acl.js file.

My db.js file looks like the following:

require('dotenv').config()
// Loading from an external file
const config = require('../../knexfile')
console.log(config)
const env = process.env.DB_ENV
console.log(env)

const knex = require('knex')(config[env])

knex.on('query', (queryData) => {
  console.log(queryData)
})

module.exports = knex

As you can see the console.log statements give back mostly undefined in the above shown output.

The knexfile.js is loading the configuration from a .env file

knexfile.js

require("dotenv").config()

module.exports = {

    development: {
        client: process.env.DB_CONNECTION,
        connection: {
            user: process.env.DB_USERNAME,
            password: process.env.DB_PASSWORD,
            database: process.env.DB_DATABASE,
        },
    },
}

.env

# Database
DB_CONNECTION=postgresql
DB_ENV=development
DB_USERNAME=root
DB_PASSWORD=root
DB_DATABASE=nodeacl

When I run knex migrate:latest or knex seed:run the seeds and migration files run perfectly.

Any suggestions why I am getting the above shown error?

回答1:

When you run knex migrate:latest and knex seed:run, it works because your file knexfile.js is located at the same level as your file .env in your file system. That means your environment variables is correctly imported.

Is your file acl.js at the same level ? If not, maybe you should run node /path/to/acl.jsfrom the .env level.

来源：https://stackoverflow.com/questions/47379839/undefined-db-connection-with-knex