db

db examples

Four steps that build on each other, each showing one concept from the CWIST database API. All four are console programs — they print to stdout and exit, no server is started.

Step	Shows
step-1-open-query	open a SQLite database behind a Unix socket with cwist_db_transfer_sqlite_to_socket + cwist_orm_open_socket, then cwist_orm_exec, cwist_orm_insert, and cwist_orm_select
step-2-migrations	versioned schema migrations with cwist_migrate_up, cwist_migrate_down, and cwist_migrate_version
step-3-zod-validate	validate JSON against a schema with cwist_zod_parse / cwist_zod_validate, and repair aliased field names with cwist_json_heal
step-4-json-insert	self-healing insert: heal broken JSON with cwist_json_heal, then insert via cwist_orm_insert

Build

Build the library first, from the repository root:

make

Then build each step (steps 1, 2, and 4 have a rule in the root Makefile, step 3 ships its own Makefile):

make example/db/step-1-open-query/open-query
make example/db/step-2-migrations/migrations
make -C example/db/step-3-zod-validate
make example/db/step-4-json-insert/json-insert

make examples-check builds all four steps.

Run

Each step is self-contained and uses an in-memory SQLite database (:memory:), so nothing persists between runs.

Step 1: open & query

./example/db/step-1-open-query/open-query

Creates a users table, inserts three rows as cJSON objects with cwist_orm_insert, and selects them back:

=== ORM: Open, Insert & Select ===
Table 'users' created
3 rows inserted via ORM

[SELECT]
  id=1    name=Alice     age=30
  id=2    name=Bob       age=25
  id=3    name=Carol     age=35

=== Done ===

Step 2: migrations

./example/db/step-2-migrations/migrations

Defines three cwist_migration_t entries — create_users (v1), add_email_to_users (v2), create_posts (v3) — then applies them all (cwist_migrate_up), rolls back one step (cwist_migrate_down with count 1), and re-applies:

[Migrate UP -- apply all]
Current version: 3

[Migrate DOWN -- roll back 1 step]
Current version after rollback: 2

[Migrate UP -- re-apply]
Current version: 3

Step 3: zod-style validation

./example/db/step-3-zod-validate/step-3-zod-validate

Declares a product schema with cwist_schema_field_t (required fields, types, and alias names: cost/amount map to price). It validates four inputs and prints one error per failed field, then shows cwist_json_heal renaming the cost alias to price so the healed document passes validation.

Step 4: self-healing JSON insert

./example/db/step-4-json-insert/json-insert

Inserts four events into an events table. Every input passes through cwist_json_heal first, so a trailing comma is repaired at level L1 and aliased fields (cat → category, points → score) are renamed at level L2. Input that cannot be healed (not json at all!!!) fails the insert. The final SELECT shows the three rows that made it:

  1   | Launch Party         | social     | 95
  2   | Team Standup         | work       | 80
  3   | Hackathon            | tech       | 90

Clean

make -C example/db/step-3-zod-validate clean
rm -f example/db/step-1-open-query/open-query \
      example/db/step-2-migrations/migrations \
      example/db/step-4-json-insert/json-insert