Migrations

Ryx can introspect your database, detect schema changes, and generate DDL automatically.

Two Approaches

Direct Migration (No Files)

Best for prototyping and simple projects:

from ryx.migrations import MigrationRunner

await ryx.setup("sqlite:///app.db")
runner = MigrationRunner([Author, Post, Tag])
await runner.migrate()

# Preview without applying
await runner.migrate(dry_run=True)

File-Based Migrations

Best for production and team projects:

# Generate migration files
python -m ryx makemigrations \
    --models myapp.models \
    --dir migrations/

# Apply migrations
python -m ryx migrate \
    --url postgres://user:pass@localhost/mydb \
    --models myapp.models

# Preview SQL
python -m ryx sqlmigrate 0001_initial --dir migrations/

# Check status
python -m ryx showmigrations \
    --url postgres://user:pass@localhost/mydb \
    --dir migrations/

How It Works

1. Introspect live DB schema → SchemaState (current)
2. Build target from Models → SchemaState (desired)
3. Diff the two states      → List of changes
4. Generate DDL             → CREATE TABLE, ALTER COLUMN, etc.
5. Execute                  → Apply to database

Migration Tracking

Ryx creates a ryx_migrations table to track applied migrations:

Column	Type
id	INTEGER
name	TEXT
applied_at	TIMESTAMP

What Migrations Handle

• Creating and dropping tables
• Adding, altering, and dropping columns
• Creating and dropping indexes
• Adding and dropping constraints
• Creating ManyToMany join tables
• Unique constraints and composite indexes

DDL Generation

Generate backend-aware DDL programmatically:

from ryx.migrations import generate_schema_ddl, DDLGenerator

# All models at once
stmts = generate_schema_ddl([Author, Post], backend="postgres")
for sql in stmts:
    print(sql)

# Fine-grained control
gen = DDLGenerator("sqlite")
print(gen.create_table(Post._meta_to_table_state()))
print(gen.add_column("posts", column_state))

Backend Differences

Feature	PostgreSQL	MySQL	SQLite
ALTER COLUMN	Yes	Yes	No (recreate table)
Native UUID	Yes	No	No
SERIAL	Yes	No	No
JSONB	Yes	No	No
Array types	Yes	No	No

Next Steps

→ Filtering — Start querying your data → CLI Reference — All migration commands