MQDB WASM - Execute (Topic Routing)

Execute — everything MQDB can do, addressed by topic

MQDB exposes every operation (CRUD, schema, constraints, indexes, catalog, health) through a single db.execute(topic, payload) call. The topic decides which operation runs. This mirrors MQTT's request/response pattern, so the same code works whether you embed MQDB in a browser or talk to it via an MQTT broker.

How it works

The topic is parsed into operation plus arguments. $DB/users/42/update → update user 42. $DB/_admin/schema/users/set → set users schema.
The payload is a plain JSON value — record fields for writes, query options for list, null when none are needed.
The result is whatever the equivalent typed method would return (the created record, the deleted id, the schema, etc).
Why this exists: MQTT brokers route by topic. Because MQDB uses the same addressing as an MQTT request, the WASM API and the over-the-network API are the same surface.
Three topic families: CRUD ($DB/{entity}/…), admin ($DB/_admin/…), and lifecycle ($DB/_health).

flowchart LR
    T["Topic: $DB/users/42/update"] --> R[Router]
    P["Payload: { name: 'Bob' }"] --> R
    R --> O1[users/create]
    R --> O2[users/42 · read]
    R --> O3[users/42/update]
    R --> O4[users/42/delete]
    R --> O5[users/list]
    R --> A1[_admin/schema/users/set]
    R --> A2[_admin/constraint/users/add]
    R --> A3[_admin/index/users/add]
    R --> A4[_admin/catalog]
    R --> H[_health]
    style R fill:#b2dfdb,stroke:#00695c
    style T fill:#e0f2f1,stroke:#00695c
    style P fill:#e0f2f1,stroke:#00695c

Try it — a four-step tour

Click the Health preset. That sets the topic to $DB/_health and payload to null. Click Execute to see { status: "ok", … }.
Click the green Create product preset. Execute → you get back the new record with its generated id.
Click List products → you see the record you just created.
Scroll to Automated test suite and click Run all tests. 13 tests run in sequence, exercising the full topic surface (CRUD, schema, constraint, index, catalog, and invalid-topic rejection).

Execute a topic

Topic

Payload

Ready.

Result

Execute a command to see results

Presets

Lifecycle

CRUD on `products`

Admin on `orders`

Topic reference

Topic	What it does
$DB/_health	Liveness / readiness check
$DB/_admin/catalog	List all known entities
$DB/{entity}/create	Create a record (payload = fields)
$DB/{entity}/{id}	Read a record
$DB/{entity}/{id}/update	Update a record (merge)
$DB/{entity}/{id}/delete	Delete a record
$DB/{entity}/list	List records (payload = query options)
$DB/_admin/schema/{entity}/set	Register / replace schema
$DB/_admin/schema/{entity}/get	Fetch the schema
$DB/_admin/constraint/{entity}/add	Add unique / not_null / foreign key
$DB/_admin/constraint/{entity}/list	List the entity's constraints
$DB/_admin/index/{entity}/add	Add a secondary index

Automated test suite

Run all tests exercises the full topic surface in 13 steps and reports pass/fail for each:

Health check returns ok
Create record via /create
Read record via /{id}
Update record via /{id}/update
List records via /list
Delete record via /{id}/delete
Set schema via _admin/schema/…/set
Get schema via _admin/schema/…/get
Add constraint via _admin/constraint/…/add
List constraints via _admin/constraint/…/list
Add index via _admin/index/…/add
Catalog via _admin/catalog
Invalid topic is rejected

Click the button to run.