parts and areas tested

backend/src/lib/getListOfModelByIDs.ts

@@ -0,0 +1,25 @@
+import { Types, Model } from "mongoose";
+
+type ObjectIdLike = Types.ObjectId | string;
+
+interface CleanRefArrayParams {
+    parentModel: Model<any>;
+    refModel: Model<any>;
+    parentId: ObjectIdLike;
+    fieldName: string;
+}
+
+export async function cleanRefArrayField({ parentModel, refModel, parentId, fieldName }: CleanRefArrayParams): Promise<{ keptIds: Types.ObjectId[]; removedIds: Types.ObjectId[] }> {
+    const parent = await parentModel.findById(parentId).lean();
+    if (!parent) { throw new Error("Parent document not found") }
+    const rawIds: ObjectIdLike[] = parent[fieldName] || [];
+    if (!Array.isArray(rawIds) || rawIds.length === 0) { return { keptIds: [], removedIds: [] } }
+    const ids = rawIds.map((id) => typeof id === "string" ? new Types.ObjectId(id) : id);
+    const existing = await refModel.find({ _id: { $in: ids } }).select("_id").lean();
+    const existingSet = new Set(existing.map((d) => String(d._id)));
+    const keptIds = ids.filter((id) => existingSet.has(String(id)));
+    const removedIds = ids.filter((id) => !existingSet.has(String(id)));
+    await parentModel.updateOne({ _id: parentId }, { $set: { [fieldName]: keptIds } });
+    return { keptIds, removedIds };
+}
+