Init system loaders

src/loaders.ts

@@ -0,0 +1,30 @@
+/**
+ * Loaders are individual DataLoader instances that can be used to query often used information more
+ * efficiently. This is relied on for fetching field information for example, seeing that's an
+ * operation we'll do often in various middleware checks
+ */
+
+import DataLoader from 'dataloader';
+import database, { schemaInspector } from './database';
+
+async function getFields(keys: { collection: string; field: string }[]) {
+	const records = await database
+		.select('*')
+		.from('directus_fields')
+		.whereIn(
+			['collection', 'field'],
+			keys.map((key) => [key.collection, key.field])
+		);
+	return keys.map((key) =>
+		records.find((record) => record.collection === key.collection && record.field === key.field)
+	);
+}
+
+export default function createSystemLoaders() {
+	return {
+		fields: new DataLoader(getFields, {
+			cacheKeyFn: (key: { collection: string; field: string }) =>
+				key.collection + '__' + key.field,
+		}),
+	};
+}