Server setup with mongodb.

Server handles creating and fetching products and their variations.
Models are saved to mongo using mongoose.
STILL PRETTY BARE BONES!

server/controllers/variation.js

@@ -0,0 +1,40 @@
+const { saveNewVariation } = require('src/variation.js')
+const Products = require('src/products');
+const products = new Products();
+
+// HELPERS
+const handleError = (error, res) => {
+  const { message, status, success } = error;
+
+  return res.status(status || 500).send({
+    success: success || false,
+    message: message || 'Unable to find product.'
+  })
+}
+
+const handleReturnProduct = (product, res) => {
+  return res.send({
+    success: true,
+    product
+  })
+}
+
+// ROUTES
+const addNewVariationToProduct = async (req, res) => {
+  const productId = req.params.id;
+  const { variation } = req.body;
+
+  console.log('id: ', productId);
+  console.log('variation: ', variation);
+
+  const newVariation = await saveNewVariation(variation);
+  
+  return saveNewVariation(variation)
+    .then(newVariation => products.addVariationToProduct(newVariation, productId))
+    .then(() => res.send('New relation added to product'))
+    .catch(err => handleError(err, res))
+}
+
+module.exports = {
+  addNewVariationToProduct
+};