chickadee » orm » define-model

Defines a model bound to the existing table name. The macro introspects the table schema at runtime (via PRAGMA table_info) and generates the following functions. A live connection must exist when the generated functions are first called.

(define-model users)

An optional model scope supplies a mandatory query condition and a row preparation callback:

(define current-account-id (make-parameter #f))

(define account-scope
  (make-model-scope
   (lambda ()
     (let ((account-id (current-account-id)))
       (unless account-id (error "account scope required"))
       (values '(= account-id ?) (list account-id))))
   (lambda (row)
     (alist-update 'account-id (current-account-id) row))))

(define-model invoices scope: account-scope)

The condition callback takes no arguments and returns two values: an ssql condition and its placeholder-value list. The ORM places this condition before any caller condition for all, find, where, and count, and includes it in the same SQL WHERE for save, update, and delete. This makes scoped writes atomic rather than a check followed by an unscoped primary-key mutation.

The optional write callback receives and returns a row alist. It runs before create and save; update delegates to scoped find and save. If omitted, it defaults to the identity function. Scope callbacks should signal an error when required context is unavailable. A configured scope that returns #f as its condition is rejected. Raw db/query and db/execute calls bypass model scopes.

The model's before-* lifecycle hooks run before the scope's write callback, so the scope is always the last writer and a hook cannot overwrite a scope-injected column. See "API: Lifecycle Hooks" below.

For a model named users, the generated functions are listed below. Each example shows the SQL that is produced (the SQLite dialect; rqlite renders identically). Assume users has columns id, name, email.