how to check if the document id is exist in case of dynamically created models/collections?

[xmarya]

I want to create a middleware function to check if the document_Id exists and it's not wrong using Model.exist({_id: id}) or such a query, so the API throws an error.

However, the problem is my models/collections are created dynamically:

• the reviews would be: Reviews-product-${productId} OR Reviews-store-${storeId}

let's assume the scenario of passing a userId to create a new dynamic model for product reviews. My code right now accepts that userId and creates a model/collection named Reviews-product-${userId} based on it because it lacks the validation step.

here are the functions that create the dynamic models/collections:

function createDynamicModel<T extends mongoose.Document>(modelName: string, schema: mongoose.Schema, collection: string): mongoose.Model<T> {
      try {
    
        let dynamicModel;
        // STEP 1) Double guard — Prevents actual Mongoose runtime error if the previous guard fall out of sync
        if (mongoose.connection.models[modelName]) dynamicModel = mongoose.connection.models[modelName] as mongoose.Model<T>;
        else dynamicModel = mongoose.connection.model<T, mongoose.Model<T>>(modelName, schema, collection);
    
        // STEP 2)Always make sure the cache is up-to-date
        lruCache.set(modelName, dynamicModel);
        console.log("inside createDynamicModel", dynamicModel);
        
        return dynamicModel;
      } catch (error) {
        console.log((error as AppError).message);
        throw new AppError(500, "couldn't create dynamic model");
      }
    }
    
    export function getDynamicModel<T extends mongoose.Document>(model: DynamicModel, modelId: string): mongoose.Model<T> {
      // only for getting reviews that are related to stores and products
    
      // STEP 1) get necessary data for dynamic model:
      const { modelName, schema, collection } = getDynamicModelData(model, modelId);
    
      if (!schema) throw new AppError(500, `Schema for model ${model} not found.`);
    
      // STEP 2) create a new modelName if it doesn't exist in the cache or in the mongoose.model:
      if (!lruCache.has(modelName) || !mongoose.connection.modelNames().includes(modelName)) createDynamicModel(modelName, schema, collection);
        
      const dynamicModel = lruCache.get(modelName) as mongoose.Model<T>;
      return dynamicModel;
    }

TL;DR when getDynamicModel is called, it is going to check if the modelName exists, if doesn't, it would create a new model. Nothing prevents a model with a wrong or non-existing id form being created

Making my Store model, which is not dynamic- know its product means keeping a reference to the products' ids inside it but then the whole logic of creating the models/collections dynamically has nonsense I've been trying to solve this since yesterday.

Your help would be highly appreciated.

[vkarpov15]

First, I strongly advise against creating a separate review collection per product or per store. I recommend having a single Reviews-product model and index on productId.

That being said, with your current setup, what prevents you from checking if a given userId exists using User.exists({ _id: userId }) in your getDynamicModel() call?

[xmarya]

I'd like to hear more about why you're against the current implementation of creating separate collections, I did that to prepare for future scaling. Something like reviews can easily get huge, so I decided to go with this path to keep the performance at its best.
Regarding the actual problem I've faced, I managed to solve it.