appCacheFetch()

Signature

appCacheFetch() — returns any

Available in: controller, model, mapper, migrator, migration, tabledefinition Category: Caching Functions

Description

Returns the value cached under key. On a miss, calls callback, caches what it returns for time and returns it. A cached false, 0 or "" counts as a hit, so callback isn’t called again until the entry expires or is deleted. When callback returns nothing, nothing is cached and "" is returned; when it throws, nothing is cached and the error propagates. callback runs outside the cache lock, so two requests that miss at the same moment may both call it (the later write wins). When the cache is full, the computed value is returned but not cached, so the next call computes it again. The cache lives in this server’s memory and empties on an application reload or restart. Keys are shared by every user, session, tenant and host: nothing about the request is added. For per-user, per-role or per-tenant data, put that identity in the key, e.g. “digest-” & userId.

Parameters

Name	Type	Required	Default	Description
key	any	yes	—	A string, or a struct or array of values (struct key order doesn’t matter).
callback	any	yes	—	A function that computes the value.
time	numeric	no	[runtime expression]	How long to keep the value, in cacheDatePart units (minutes by default).