spuneiartur/db-seed-generator

Database Seed & Script Generator

Generates database seed files (db/seeds/) for repeatable initial data and standalone scripts (scripts/) for one-off migrations and imports. Both follow established patterns and connect to MongoDB properly.

When to Use

• "Create seed data for reviews"
• "Import products from this JSON file"
• "Write a migration script to add slugs to all categories"
• "Seed the database with test users"
• "Bulk update all products to set isActive = true"

Two Types

Seeds (db/seeds/)

• Repeatable initial data loaded via npm run seed
• Numbered for execution order: 001_identities.js, 002_categories.js
• Data factories live in db/resources/
• Registered in db/seeds/index.js

Scripts (scripts/)

• One-off operations: imports, migrations, data fixes
• Run via node npm.js {script-name} (without .js extension)
• Use runScript() from express-goodies/functions for DB connection
• Self-contained — handle their own connection and logging

Workflow

For Seeds

Step 1: Determine sequence number

Check existing seeds in db/seeds/ to find the next number:

001_identities.js
002_xxx.js  ← next would be 002 or whatever follows

Step 2: Create the data factory — db/resources/{resource}.js

Read references/seed-template.md for the complete pattern.

const {resources} = () => {
  return [
    {
      name: 'Example Item 1',
      // fields matching the model schema
    },
    {
      name: 'Example Item 2',
    },
  ];
};

export default {resources};

If data needs async processing (e.g. hashing passwords), make it async:

import bcrypt from 'bcryptjs';

const identities = async () => {
  const password = await bcrypt.hash('password123', 10);
  return [
    { email: '[email protected]', password, role: 'admin' },
  ];
};

export default identities;

Step 3: Create the seed runner — db/seeds/{NNN}_{resource}.js

import { {Resource} } from '@models';
import {resources} from '../resources/{resources}';

export async function seed() {
  try {
    console.log('Planting seeds for {resources}...');

    const seeds = await {resources}();
    await {Resource}.insertMany(seeds);

    console.log('✓');
  } catch (err) {
    console.warn('Error! Cannot insert {resources}');
    console.error(err);
  }
}

Step 4: Register in db/seeds/index.js

export * as {resources} from './{NNN}_{resources}';

For Scripts

Step 1: Create the script — scripts/{action}-{resource}.js

Read references/script-template.md for the complete pattern.

import { {Resource} } from '@models';
import { runScript } from 'express-goodies/functions';

/**
 * Usage:
 * node npm.js {action}-{resource}
 */
runScript(script);

async function script() {
  console.log('Starting {action} for {resources}...');

  // Script logic here

  console.log('Done!');
}

runScript() handles: connecting to MongoDB, running the script function, disconnecting, and exiting the process. You don't need to manage the DB connection manually.

Common Script Patterns

Import from JSON/array:

async function script() {
  console.log('Starting import...');

  let created = 0;
  let skipped = 0;

  for (const item of data) {
    const existing = await Resource.findOne({ slug: item.slug });

    if (existing) {
      console.log(`Skipped (already exists): ${item.slug}`);
      skipped++;
      continue;
    }

    await Resource.create(item);
    console.log(`Created: ${item.name}`);
    created++;
  }

  console.log(`\nImport complete: ${created} created, ${skipped} skipped`);
}

Bulk update:

async function script() {
  console.log('Updating all resources...');

  const result = await Resource.updateMany(
    { isActive: { $exists: false } },
    { $set: { isActive: true } }
  );

  console.log(`Updated ${result.modifiedCount} documents`);
}

Migration (add field/transform data):

async function script() {
  console.log('Migrating resources...');

  const documents = await Resource.find({});

  for (const doc of documents) {
    const slug = doc.name.toLowerCase().replace(/\s+/g, '-');
    await Resource.findByIdAndUpdate(doc._id, { slug });
    console.log(`Migrated: ${doc.name} → ${slug}`);
  }

  console.log(`Migrated ${documents.length} documents`);
}

Important Rules

• Seeds use insertMany for bulk inserts — fast but no validation hooks
• Scripts use create or findByIdAndUpdate for individual operations — slower but triggers hooks
• Always add console logging for progress tracking
• Scripts should be idempotent when possible (check for existing data before creating)
• Use @models alias for model imports
• Use runScript() from express-goodies/functions for scripts — it handles DB connection

Reference Files

• references/seed-template.md — Complete seed example (identities)
• references/script-template.md — Complete script example (import-articles)