restloom/docs/writes.md

Writes and procedures

Writes are off until a resource enables them. The examples on this page run with these options, against the demo schema:

resources: {
    tags: { write: true },
    assets: { write: { create: ['name', 'status', 'owner_id', 'cost'], update: ['name', 'status', 'owner_id'], delete: false } },
    incidents: { write: { create: true, update: true, delete: true, bulk: true } },
},
procedures: {
    'assets/{asset}/retire': { function: 'demo.retire_asset' },
    'tags/{tag}/assets': { function: 'demo.assets_tagged' },
},

write: true allows create, update and delete of every visible column. A list allows only the columns named. Generated and identity columns are never writable, and neither is a key on update.

Method	Path	Does	Answers
POST	/tags	creates one row, or an array of rows	201
PATCH	/tags/4	updates one row	204, or 200 with the row
DELETE	/tags/4	deletes one row	204, or 200 with the row
PATCH, DELETE	/incidents?severity=lt.3	by filter, only where bulk: true	204, or 200 with the rows

Getting the rows back

Without a Prefer header a write answers with no body. Prefer: return=representation answers the written rows, read back with the request's select, so embeds work too.

POST /tags?select=id,name
Prefer: return=representation

{ "id": 4, "name": "critical" }

Answer: 201

[{ "id": 4, "name": "critical" }]

POST /tags

[{ "id": 5, "name": "legacy" }, { "id": 6, "name": "edge" }]

Answer: 201

Every row of a body names the same columns, so one statement writes them all.

POST /tags

[{ "id": 7, "name": "a" }, { "name": "b" }]

{ "error": "mixed_columns" }

A column outside the resource's writable list is refused, whatever its value:

POST /assets

{ "name": "new laptop", "status": "open", "active": false }

{ "error": "not_writable", "message": "active" }

Updating and deleting

PATCH and DELETE act on one row, by its key. A row that does not exist, or is not visible, answers 404.

PATCH /assets/2?select=id,name,owner(name)
Prefer: return=representation

{ "owner_id": 1 }

Answer: 200

{ "id": 2, "name": "mail relay", "owner": { "name": "Ada" } }

DELETE /tags/4

Answer: 204

A row still referenced by another is not deleted:

DELETE /tags/3

{ "error": "still_referenced" }

DELETE /assets/1

{ "error": "method_not_allowed" }

A resource with bulk: true also takes PATCH and DELETE on the collection, with at least one filter. Without a filter they are refused, so no request can empty a table by accident.

DELETE /incidents?severity=lt.3&select=id,title
Prefer: return=representation

Answer: 200

[{ "id": 2, "title": "Spoofed mail" }]

DELETE /incidents

{ "error": "filter_required" }

Values

Body values are checked against each column's type, as query values are: a number for a number column, true or false for a boolean, a string in ISO 8601 for a date or a time. The database's own constraints answer with stable codes:

POST /tags

{ "id": 1, "name": "duplicate key" }

{ "error": "duplicate" }

POST /incidents

{ "id": 9, "title": "Lost badge", "asset_id": 99, "severity": 1, "opened_on": "2026-04-01" }

{ "error": "reference_missing" }

Procedures

A procedure calls a database function at a path you choose. A {name} in the path passes that segment as the argument of the same name; the body's keys pass the others. Arguments are checked by name and type, and one with a default may be left out. A procedure is always a POST.

POST /assets/3/retire

{ "reason": "end of life" }

3

A function returning a set answers an array of its rows. Mail relay belongs to Ada since the update above.

POST /tags/gdpr/assets

[
  { "id": 2, "name": "mail relay", "status": "open", "owner_id": 1, "cost": 300, "active": true, "created_at": "2026-01-05T09:30:00+00:00" },
  { "id": 4, "name": "payroll db", "status": "open", "owner_id": 3, "cost": 4000, "active": true, "created_at": "2026-02-11T16:45:00+00:00" }
]

POST /assets/3/retire

{ "why": "no reason" }

{ "error": "unknown_argument", "message": "why" }