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JavaScript

Posted by Doug Hawkinson
.a{fill-rule:evenodd;}techdegree
Doug Hawkinson
Full Stack JavaScript Techdegree Student 25,073 Points

I need help converting a file into a reusable module in node.

I am using the following file to seed a mongodb database. This file runs exactly as it should and returns exactly the result I am expecting, when I execute it as a standalone file. My issue is I want to use this file in two different places in my app. So I am trying to make it an exportable/importable module. Here is what I have tried:

seed.js looks like this:

'use strict';

//  library modules
const {ObjectID} = require('mongodb');
const seeder     = require('mongoose-seed');    //  NOTE: rejected "mongoose-seeder" because it seems to be out of sync with mongodb
const jwt        = require('jsonwebtoken');
const util       = require('util');

//  local modules
const {Course}   = require('./../models/course');
const {Review}   = require('./../models/review');
const {User}     = require('./../models/user');
const {data}     = require('./../data/data.js');
const config     = require('./../config/config.js');

/*==================================================
    build seeding Courses, Reviews, Users
==================================================*/

// Connect to MongoDB via Mongoose
let seed = seeder.connect(process.env.MONGODB_URI, (e) => {
    console.log(`Connected to: ${process.env.MONGODB_URI} and seeding files`);

    // Load Mongoose models
    seeder.loadModels([
        'src/models/user.js',
        'src/models/review.js',
        'src/models/course.js'
    ]);

    // Clear specified collections
    seeder.clearModels(['User', 'Review', 'Course'], function() {

        // Callback to populate DB once collections have been cleared
            seeder.populateModels(data, function() {
            seeder.disconnect();
        });

    });
});

module.exports = seed;

Within app.js I have these two lines

const seed         = require('./middleware/seed');

and

app.use(seed);

I have also tried, to no avail

app.use(seed());

What is missing? I don't want to use the code in line in two different places (DRY you know).

It is failing with "throw new TypeError('app.use() requires a middleware function')"

Jennifer Nordell
seal-mask
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi there! Out of curiosity, what happens when you try module.exports.seed = seed; ? I feel like the problem might lie in the exporting of the module.

1 Answer

Doug Hawkinson
.a{fill-rule:evenodd;}techdegree
Doug Hawkinson
Full Stack JavaScript Techdegree Student 25,073 Points

OK, for those interested, here is the solution. My seed.js file needed to be modified as follows:

/*==================================================
    build seeding Courses, Reviews, Users
==================================================*/

// declare seeding
function seedDB(next) {
    seeder.connect(process.env.MONGODB_URI, (e) => {
        console.log(`Connected to: ${process.env.MONGODB_URI} and seeding files`);

        // Load Mongoose models
        seeder.loadModels([
            'src/models/user.js',
            'src/models/review.js',
            'src/models/course.js'
        ]);

        // Clear specified collections
        seeder.clearModels(['User', 'Review', 'Course'], function() {

            // Callback to populate DB once collections have been cleared
                seeder.populateModels(data, function() {
                seeder.disconnect();
            });

        });
    });
}

//  execute seeding
seedDB();

const seed = (req, res, next) => {
    seedDB(next());
};

module.exports = seed;

middleware must always be a function with a next(), mine wasn't.