text: // import models
  const Product = require('./product');
  const Category = require('./category');
  const Tag = require('./tag');
  const ProductTag = require('./ProductTag');
  
  // Products belongsTo Category
  Product.belongsTo(Category, {
    foreignKey: 'category-id'
  });
  
  // Categories have many Products
  Category.hasMany(Product, {
    foreignKey: 'category-id'
  })
  
  // Products belongToMany Tags (through ProductTag)
  Product.belongsToMany(Tag, {
    through: ProductTag,
    foreignKey: 'product-id'
  })
  
  // Tags belongToMany Products (through ProductTag)
  Tag.belongsToMany(Product, {
    through: ProductTag, 
    foreignKey: 'tag_id'
  })
  
  module.exports = {
    Product,
    Category,
    Tag,
    ProductTag,
  };
  