     posts = _.map productsToProcess, (prodToProcess) =>
       existingProduct = @_isExistingEntry(prodToProcess, existingProducts)
       if existingProduct?
+        if not prodToProcess.slug
+          debug 'slug missing in product to process, assigning same as existing product: %s', existingProduct.slug
+          prodToProcess.slug = existingProduct.slug # to prevent removing slug from existing product.
         synced = @sync.buildActions(prodToProcess, existingProduct)
         if synced.shouldUpdate()
           @client.products.byId(synced.getUpdateId()).update(synced.getUpdatePayload())

      @_resolveReference(@client.productTypes, 'productType', product.productType, "name=\"#{product.productType?.id}\"")
      @_resolveProductCategories(product.categories)
      @_resolveReference(@client.taxCategories, 'taxCategory', product.taxCategory, "name=\"#{product.taxCategory?.id}\"")
    ]
    .spread (prodTypeId, prodCatsIds, taxCatId) ->
      if prodTypeId
        product.productType =
          id: prodTypeId

_ = require 'underscore'
_.mixin require 'underscore-mixins'
Promise = require 'bluebird'
slugify = require 'underscore.string/slugify'
{SphereClient, ProductSync} = require 'sphere-node-sdk'

class ProductImport
