Database Seeding and Schema Migrations

Seeding and Managing Migrations

Database seeding populates your development environment with realistic data. Migrations track schema changes over time like version control for your database.

Prisma Seed Script

// prisma/seed.ts
import { PrismaClient } from '@prisma/client';
import bcrypt from 'bcryptjs';

const db = new PrismaClient();

async function main() {
    // Create admin user
    const admin = await db.user.upsert({
        where: { email: 'admin@example.com' },
        update: {},
        create: {
            name: 'Admin User',
            email: 'admin@example.com',
            password: await bcrypt.hash('password', 10),
            role: 'ADMIN',
        },
    });

    // Create categories
    const categories = await Promise.all([
        db.category.upsert({
            where: { slug: 'tutorials' },
            update: {},
            create: { name: 'Tutorials', slug: 'tutorials' },
        }),
        db.category.upsert({
            where: { slug: 'news' },
            update: {},
            create: { name: 'News', slug: 'news' },
        }),
    ]);

    // Create sample posts
    for (let i = 1; i <= 10; i++) {
        await db.post.upsert({
            where: { slug: `sample-post-${i}` },
            update: {},
            create: {
                title: `Sample Post ${i}`,
                slug: `sample-post-${i}`,
                content: `This is the content for sample post ${i}. `.repeat(20),
                excerpt: `Excerpt for sample post ${i}`,
                published: true,
                publishedAt: new Date(Date.now() - i * 86400000),
                authorId: admin.id,
                categoryId: categories[i % 2].id,
            },
        });
    }

    console.log('Database seeded successfully');
}

main()
    .catch(console.error)
    .finally(() => db.$disconnect());

// package.json
{
    "prisma": {
        "seed": "ts-node --compiler-options '{\"module\":\"CommonJS\"}' prisma/seed.ts"
    }
}

npx prisma db seed

Migration Workflow

# 1. Modify schema.prisma
# 2. Create migration
npx prisma migrate dev --name add_view_count_to_posts

# 3. Prisma generates the SQL migration file
# prisma/migrations/20241015_add_view_count_to_posts/migration.sql

# 4. Apply in production (CI/CD)
npx prisma migrate deploy

Deploying Migrations Safely

In your deployment script:

#!/bin/bash
# Run migrations before starting the server
npx prisma migrate deploy

# Then start the application
npm run start

Never run prisma migrate dev in production — it prompts interactively and may reset data. Always use migrate deploy in CI/CD pipelines.