Seeding your database

Populate your database with initial data for reproducible environments across local and testing.

When you run supabase init we create an empty seed.sql file in the root of the supabase folder. You can use this to populate your database with seed data.

What is seed data?

Seeding is the process of populating a database with initial data, typically used to provide sample or default records for testing and development purposes. You can use this to create "reproducible environments" for local development, staging, and production.

Using the seed file

The seed.sql file is run every time you run supabase start or supabase db reset. Seeding is done after all the database migrations have been run. As a general rule, you should not add schema statements to your seed file, only data.

You can add any SQL statements to this file. For example:

supabase/seed.sql

insert into countries
  (name, code)
values
  ('United States', 'US'),
  ('Canada', 'CA'),
  ('Mexico', 'MX');

Generating seed data

You can generate seed data for local development using Snaplet.

If this is your first time using Snaplet to seed your project, you'll need to setup Snaplet for your project with npx @snaplet/seed init, and follow the interactive prompts. The command will look at your database and its structure, and use it to generate the configuration files and assets needed by @snaplet/seed.

Suppose you have a database with the following schema:

An example schema

You can use the seed script example generated by Snaplet seed.ts to define the values you want to generate. For example:

A Post with the title "There is a lot of snow around here!"
The Post.createdBy user with an email address ending in "@acme.org"
Three Post.comments from three different users.

seed.ts

import { createSeedClient } from '@snaplet/seed'
import { copycat } from '@snaplet/copycat'

async function main() {
  const seed = await createSeedClient({ dryRun: true })

  await seed.Post([
    {
      title: 'There is a lot of snow around here!',
      createdBy: {
        email: (ctx) =>
          copycat.email(ctx.seed, {
            domain: 'acme.org',
          }),
      },
      Comment: (x) => x(3),
    },
  ])

  process.exit()
}

main()

Running npx tsx seed.ts > supabase/seed.sql generates the relevant SQL statements inside your supabase/seed.sql file:

-- The `Post.createdBy` user with an email address ending in `"@acme.org"`
INSERT INTO "User" (name, email) VALUES ("John Snow", "snow@acme.org")

--- A `Post` with the title `"There is a lot of snow around here!"`
INSERT INTO "Post" (title, content, createdBy) VALUES (
  "There is a lot of snow around here!",
  "Lorem ipsum dolar",
  1)

--- Three `Post.Comment` from three different users.
INSERT INTO "User" (name, email) VALUES ("Stephanie Shadow", "shadow@domain.com")
INSERT INTO "Comment" (text, userId, postId) VALUES ("I love cheese", 2, 1)

INSERT INTO "User" (name, email) VALUES ("John Rambo", "rambo@trymore.dev")
INSERT INTO "Comment" (text, userId, postId) VALUES ("Lorem ipsum dolar sit", 3, 1)

INSERT INTO "User" (name, email) VALUES ("Steven Plank", "s@plank.org")
INSERT INTO "Comment" (text, userId, postId) VALUES ("Actually, that's not correct...", 4, 1)

Whenever your database structure changes, @snaplet/seed will need to be regenerated so that it is in sync with your new database structure. You can do this by running npx @snaplet/seed sync.

For more information, check out Snaplet's seed documentation

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Seeding your database

Populate your database with initial data for reproducible environments across local and testing.

What is seed data?#

Using the seed file#

Generating seed data#

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What is seed data?

Using the seed file

Generating seed data