restloom/docs/discovery.md

Discovery and overrides

restloom reads the database's catalog once, on the first request, and builds the API from it. rest.reload() reads it again on the next request, after a migration for example.

What becomes a resource

expose names what is served. Nothing else is.

expose: { schemas: ['app'] }                       // every table and view of app
expose: { tables: ['app.todos', 'app.users'] }    // only these

A resource is named after its table. When two exposed schemas hold a table of the same name, both are named schema_table. resources.<name>.expose: false removes one, for example a junction table you only want used as a relation:

resources: { todo_tags: { expose: false } }

A resource's key is its primary key. A view has none, so it uses a column named id when it has one, or the columns you give it: resources: { todo_rows: { key: ['todo_id'] } }. A resource without a key can still be listed, but has no /{id} path and no stable page order.

Columns

Every column is visible except:

• Sensitive names: columns whose name contains one of these words: password, passwd, pwd, hash, hashed, salt, secret, token, api_key, private_key, otp, totp, mfa, recovery. A word is a whole part of the name between underscores: password_hash and reset_token are hidden, tokenizer is not.
• Columns you hide: resources: { users: { hide: ['phone'] } }.

show makes a sensitive-looking column visible on purpose: resources: { files: { show: ['sha256_hash'] } }. sensitive replaces the whole list with your own pattern.

A hidden column cannot be read, filtered, sorted or written, and naming it answers exactly as naming a column that does not exist. It can still join a relation.

Relations

Relations come from foreign keys between exposed resources:

In the catalog	Gives
todos.owner_id references users.id	todos.owner, to-one; users.todos, to-many
todo_tags has a primary key made of a key to todos and a key to tags	todos.tags and tags.todos, many-to-many

Names:

• To-one: the foreign key column without _id (owner_id gives owner). Otherwise the target table's name.
• To-many: the source table's name.
• Collisions: when a name is taken by a column or another relation, the next candidate is used. For to-one, that is the target table's name, then <column>_<table>. For to-many, it is <table>_by_<column>, and for many-to-many <table>_via_<junction>.

A relation to a table that is not exposed does not exist. A foreign key to a hidden table exposes nothing.

relations overrides, adds or removes them:

resources: {
    users: {
        relations: {
            users: false,                                    // remove the discovered one
            reports: { many: 'users', via: 'manager_id' },   // to-many: users whose manager_id is my key
            team: { one: 'teams', via: 'team_id' },          // to-one, e.g. for a view without foreign keys
            badges: { many: 'badges', through: 'user_badges' },
        },
    },
}

An override with the name of a column is refused when the catalog is read, and so is any option naming a resource, column or table that does not exist. Call await rest.resources() at start so a typo stops your server from booting instead of failing its first request.