toucan2.tools.helpers — io.github.camsaul/toucan2 0.10.1-alpha-SNAPSHOT

before-delete clj

(before-delete model instance)

default-fields clj

(default-fields model)

define-before-delete clj macro

(define-before-delete model [instance-binding] & body)

define-before-select clj macro

(define-before-select model [args-binding] & body)

(define-before-select [model query-class] [args-binding] & body)

define-default-fields clj macro

(define-default-fields model & body)

deftransforms clj macro

(deftransforms model transforms)

Define type transforms to use for a specific model. transforms should be a map of

{:column-name {:in <fn>, :out <fn>}}

:in transforms are applied to values going over the wire to the database; these generally only applied to values passed at or near the top level to various functions; don't expect Toucan 2 to parse your SQL to find out which parameter corresponds to what in order to apply transforms or to apply transforms inside JOINS in hand-written HoneySQL. That said, unless you're doing something weird your transforms should generally get applied.

:out transforms are applied to values coming out of the database; since nothing weird really happens there this is done consistently.

Transform functions for either case are skipped for nil values.

Example:

(deftransforms :models/user {:type {:in name, :out keyword}})

You can also define transforms independently, and derive a model from them:

(deftransforms ::type-keyword {:type {:in name, :out keyword}})

(derive :models/user ::type-keyword) (derive :models/user ::some-other-transform)

Don't derive a model from multiple deftransforms for the same key in the same direction.

When multiple transforms match a given model they are combined into a single map of transforms with merge-with merge. If multiple transforms match a given column in a given direction, only one of them will be used; you should assume which one is used is indeterminate. (This may be made an error, or at least a warning, in the future.)

Until upstream issue https://github.com/camsaul/methodical/issues/97 is resolved, you will have to specify which method should be applied first in cases of ambiguity using [[methodical.core/prefer-method!]]:

(m/prefer-method! transformed/transforms ::user-with-location ::user-with-password)

If you want to override transforms completely for a model, and ignore transforms from ancestors of a model, you can create an :around method:

(defmethod toucan2.tools.transformed/transforms :around ::my-model [_model] {:field {:in name, :out keyword}})

do-before-select clj

(do-before-select model thunk)