Data Viewer
Admin-only data inspection extension for Caffeine AI.
Overview
Every Caffeine app ships with the caffeineai-data-viewer mops package and the moc --generate-view-queries flag enabled. Together with include MixinViews() in the actor, the compiler auto-exposes a controller-only __<var> query for every stable variable of a supported type:
Map.Map<K, V>—(?K, ?Nat) -> [(K, V)]Set.Set<K>—(?K, ?Nat) -> [K][V],[var V],List.List<V>,Stack.Stack<V>,Queue.Queue<V>—(?Nat, ?Nat) -> [V]
A null cursor starts at the beginning; a null count returns everything from the cursor. Each generated query traps on any non-controller caller — they exist for admin dashboards and debug viewers, not user-facing endpoints.
Backend
The package and include are already wired into the template. You don't need to add or edit anything for the viewer to work — declare a stable variable of a supported type and the __<var> query appears automatically.
import Map "mo:core/Map";
import Principal "mo:core/Principal";
import MixinViews "mo:caffeineai-data-viewer/MixinViews";
actor {
include MixinViews();
let users = Map.empty<Principal, Text>();
// Generated automatically: __users : (ko : ?Principal, count : ?Nat) -> [(Principal, Text)] query
};Lintoko rule include-mixin-views (shipped with the package) errors if the actor body is missing include MixinViews();. Keep the include — removing it disables every auto-generated viewer.
Rules
- NEVER use the generated
__<var>queries as a substitute for user-facing endpoints — they trap for any non-controller caller. Public list/feed/search methods still need to be written normally withpublic query func listX(...). - NEVER declare an actor member whose name starts with
__— it either collides with an auto-generated query or hits a reserved prefix. - Pure (immutable) collections (
pure/Map,pure/Set,pure/List,pure/Queue) are not supported. The viewer is mutable-only by design; pure collection field access is a deprecated pattern in Caffeine projects anyway.
