Express 有没有办法在pre-find-hook中设置参数？

参考：“产品”， localField:“\u id”， foreignField:“主要产品” });

有没有办法在pre-find hook中设置一个参数，这样我就可以只找到具有

productType=“main

”的产品。这是因为我正在填充每个mainProduct的变体，所以不想重复对变体的查询

const productSchema = new Schema(
{
    name: { type: String, required: true },
    category: { type: Schema.Types.ObjectId, ref: 'Category'},
    user: { type: Schema.Types.ObjectId, ref: "User" },
    description: { type: String, required: true },
    mainProduct: { type: Schema.Types.ObjectId, ref: 'Product'},
      productType: {
      type: String,
      enum: productTypes,
      default: "main",
      },
    
     },
  {
    timestamps: true,
        toJSON: { virtuals: true } 
        }
         );
    
          productSchema .pre("find", function (next) {
         //only find the product which have productype='main' 
           this.populate({ path: 'category' }).populate({ path: 'user' }).populate('variants');
  
  

     next();
    });
productSchema.virtual('variants', {