Seed Data

SchemaHero can insert seed data into tables after they're created or updated.

Basic Usage

Add a seedData section to your table definition:

apiVersion: schemas.schemahero.io/v1alpha4
kind: Table
metadata:
  name: roles
spec:
  database: myapp
  name: roles
  schema:
    postgres:
      primaryKey: [id]
      columns:
        - name: id
          type: serial
        - name: name
          type: varchar(50)
        - name: description
          type: text
  seedData:
    rows:
      - id: 1
        name: admin
        description: Full system access
      - id: 2
        name: editor
        description: Can edit content
      - id: 3
        name: viewer
        description: Read-only access

When Seed Data Runs

Seed data is applied:

After the table is created (for new tables)
After schema changes are applied (for existing tables)
Only when there are no schema changes but seed data changed

Seed data uses INSERT ... ON CONFLICT DO NOTHING (PostgreSQL) or equivalent, so existing rows are not overwritten.

Use Cases

Lookup Tables

apiVersion: schemas.schemahero.io/v1alpha4
kind: Table
metadata:
  name: countries
spec:
  database: myapp
  name: countries
  schema:
    postgres:
      primaryKey: [code]
      columns:
        - name: code
          type: char(2)
        - name: name
          type: varchar(100)
  seedData:
    rows:
      - code: US
        name: United States
      - code: CA
        name: Canada
      - code: GB
        name: United Kingdom
      # ... more countries

Default Configuration

apiVersion: schemas.schemahero.io/v1alpha4
kind: Table
metadata:
  name: settings
spec:
  database: myapp
  name: settings
  schema:
    postgres:
      primaryKey: [key]
      columns:
        - name: key
          type: varchar(100)
        - name: value
          type: text
  seedData:
    rows:
      - key: site_name
        value: My Application
      - key: max_upload_size
        value: "10485760"
      - key: enable_registration
        value: "true"

Test Users (Development Only)

For development environments, you might seed test users:

# schema/dev/test-users.yaml
apiVersion: schemas.schemahero.io/v1alpha4
kind: Table
metadata:
  name: users-seed
spec:
  database: myapp
  name: users
  schema:
    postgres:
      primaryKey: [id]
      columns:
        - name: id
          type: uuid
        - name: email
          type: varchar(255)
        - name: role_id
          type: int
  seedData:
    rows:
      - id: 00000000-0000-0000-0000-000000000001
        email: admin@example.com
        role_id: 1
      - id: 00000000-0000-0000-0000-000000000002
        email: test@example.com
        role_id: 3

Only apply this in dev:

schemahero plan --spec-file ./schema/base/ --spec-file ./schema/dev/ ...

Data Types

Strings

seedData:
  rows:
    - name: "John Doe"
      bio: |
        Multi-line
        biography text

Numbers

seedData:
  rows:
    - count: 42
      price: 19.99

Booleans

seedData:
  rows:
    - active: true
      deleted: false

NULL Values

Omit the column or use explicit null:

seedData:
  rows:
    - name: Test
      optional_field: null

UUIDs

seedData:
  rows:
    - id: 550e8400-e29b-41d4-a716-446655440000

Timestamps

seedData:
  rows:
    - created_at: "2024-01-15T10:30:00Z"

Limitations

Seed data does not update existing rows (insert only)
Seed data does not delete rows removed from the YAML
Complex data types (JSON, arrays) may need string encoding
Large datasets should use a dedicated data loading tool

Generating Fixtures

SchemaHero can generate table definitions from an existing database:

schemahero generate \
  --driver postgres \
  --uri "postgres://..." \
  --output-dir ./schema/

This creates YAML files for each table but does not include seed data. You'll need to add seed data manually or export it separately.

Organizing Schemas Testing Schemas