How to generate and apply migrations

Generating and applying migrations follows the same workflow used by the example applications.

Install @danceroutine/tango-cli as a development dependency before you begin. Most applications also keep a tango.config.ts file at the project root so the CLI can infer the dialect, database target, and migration directory.

1. Export your models from one module

The make:migrations command loads a module and collects every exported value that looks like a Tango model.

In the examples, those modules are:

• examples/blog-api/src/models/index.ts
• examples/nextjs-blog/src/lib/models.ts

2. Generate a migration

With tango.config.ts at the project root:

pnpm exec tango make:migrations \
  --config ./tango.config.ts \
  --models ./src/models/index.ts \
  --name add_summary

If your config file lives at ./tango.config.ts, the CLI will auto-load it even when you omit --config.

Explicit flags such as --dialect, --db, and --dir override the values inferred from config. Use that path when you need to target a different database or a nonstandard migration directory for a single command.

3. Review the generated file

Review the generated file before applying anything so you understand exactly which operations Tango believes are necessary.

diffSchema() can detect table, column, and index differences, but generated operations still deserve review, especially around renames and deletions.

Check for:

• unexpected drop() calls
• dropped columns you meant to rename
• missing indexes
• incorrect table names caused by a changed namespace or model name

4. Apply the migration

pnpm exec tango migrate --config ./tango.config.ts

The examples wrap this in setup:schema scripts so the command is easier to reuse.

5. Verify status or inspect the SQL plan

To see what would run without applying it:

pnpm exec tango plan --config ./tango.config.ts

To see which migrations are applied:

pnpm exec tango status --config ./tango.config.ts

6. Re-run the generation step after applying

Run make:migrations again after the migration is applied.

If the database and the model metadata are in sync, the CLI should report no changes.

Related pages

• Config API
• Run Tango in CI/CD
• Migrations topic
• Configure databases
• CLI API