Swapping unique values in mongoose without swapping all properties

salon_sue

I need to swap a value of a field with a unique constraint ( order ) between several (>2) documents in a MongoDB collection without having to swap the document content (see this answer ). This is because I need to preserve the _id of each document. The solution below obviously does not work; it throws E11000 duplicate key error collection . const CategoryModel = new mongoose.Schema({ order: {type: Number, required: true, unique: true} }); // for...

Originally asked by user33267884 on Stack Exchange (stackoverflow) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

You can avoid the duplicate key error by first moving the affected documents to temporary order values, then assigning their new positions. For example: const session = await mongoose.startSession(); try { await session.withTransaction(async () => { const lastCategory = await CategoryModel .findOne() .sort({ order: -1 }) .select({ order: 1 }) .session(session); let tempOrder = (lastCategory?.order ?? -1) + 1; // Temporarily move the affected documents for (const category of newCategories) { await CategoryModel.updateOne( { _id: category.categoryId }, { $set: { order: tempOrder++ } }, { session } ); } // Assign the requested order values for (const category of newCategories) { await...

Full answer by Faheem: https://stackoverflow.stackexchange.com/a/80014291 (CC BY-SA 4.0).

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