Update Shopify Inventory from CSV Files On Your FTP Server

This scheduled trigger connects to your FTP server hourly and fetches a CSV file that you specify. You need to configure several settings during setup:

(1) FTP credentials—configure your FTP server connection details in MESA's FTP integration settings,
(2) File path—enter the path to your CSV file (you can use wildcards like "inventory/Stock.csv" to match multiple files),
(3) CSV format requirements—your CSV must include columns named "SKU" and "Inventory" (case-sensitive), and
(4) Schedule—adjust the frequency if hourly is too often or not frequent enough for your needs.

The CSV data is parsed into an array where each row becomes an object accessible as {{ftp}} with properties like {{ftp.SKU}} and {{ftp.Inventory}}.

This loop step iterates through each row in the CSV file stored in {{ftp}}. For every row, the loop executes the subsequent SKU lookup and inventory update steps using {{loop.SKU}} and {{loop.Inventory}} as the data for that specific product. The loop uses custom code to enqueue each iteration as a separate task, enabling efficient processing of large CSV files without timeout issues.

const Mesa = require("vendor/Mesa.js");
const Loop = require('vendor/Loop.js');
module.exports = new class {
  script = (payload, context) => {
    // Loop over each item and enqueue child tasks for each matching item
    Loop.process(payload, context, (match, key) => {      
      match.key = match.key ? match.key : key;
      Mesa.output.nextOutput(match, {enqueue: true});
    });
  }
}

This custom code step uses Shopify's GraphQL API to search for a product variant matching {{loop.SKU}} from the current CSV row. The GraphQL query searches for "sku:[YOUR_SKU]" and returns the variant's inventory item ID. The code extracts the numeric ID from Shopify's GraphQL ID format (which looks like "gid://shopify/InventoryItem/12345") and stores it as {{custom.inventory_item_id}}. If no matching SKU is found, the code logs a message and stops processing that row without attempting an inventory update, preventing errors for SKUs that don't exist in your Shopify store.

const Mesa = require('vendor/Mesa.js');
const ShopifyGraphql = require('vendor/ShopifyGraphql.js');
module.exports = new class {
  script = (payload, context) => {
    const vars = context.steps;
    let inventoryItemIdGid = 0;
    const productSku = vars.loop.SKU;
    
    Mesa.log.info("Product SKU", productSku);
    
    // GraphQL query to find variant by SKU
    let query = `
      query($query: String!) {
        productVariants(first: 3, query: $query) {
          edges {
            node {
              displayName
              id
              sku
              inventoryItem {
                id
              }
              product {
                id
                title
              }

            }
          }
        }
      }
    `;
    
    const response = ShopifyGraphql.send(query, {
      "query": "sku:" + productSku,
    });
    
    Mesa.log.info("Response", response);
    
    // Extract inventory item ID from response
    if (
      response && 
      response.data &&
      response.data.productVariants &&
      response.data.productVariants.edges[0] &&
      response.data.productVariants.edges[0].node &&
      response.data.productVariants.edges[0].node.inventoryItem &&
      response.data.productVariants.edges[0].node.inventoryItem.id
    ) {
      inventoryItemIdGid = response.data.productVariants.edges[0].node.inventoryItem.id;
      vars.loop.inventory_item_id = inventoryItemIdGid.match(/\d+/)[0];
      
      Mesa.log.info("Inventory Item ID", vars.loop.inventory_item_id);
      Mesa.output.next(vars.loop);
    } else {
      Mesa.log.info('No Inventory Item ID found. SKU does not exist.');
    }
  }
}

This step sets the inventory level for the product variant using {{custom.inventory_item_id}} (from the SKU lookup), {{loop.Inventory}} (the quantity from the CSV), and a location_id that you configure during setup.

You need to find your Shopify location ID by going to Settings > Locations in Shopify admin, clicking on the location where you track inventory, and looking at the URL which will show a number like "12345678901"—that's your location ID.

The inventory is set (not adjusted), meaning the quantity in Shopify will exactly match the CSV value regardless of what it was before. This ensures your CSV is always the source of truth.