When syncing complex data with Monday.com, updating subitems one by one inside a loop can quickly drain your task limits and slow down your workflows. This guide explains how to use a custom code step in Zapier to update multiple subitems simultaneously using a single, batched GraphQL mutation.

By passing comma-separated lists of data into a single JavaScript step, you can bypass the need for looping through individual "Update Item" actions.

How the batch update works

The script takes your comma-separated lists of subitem IDs and product details, maps them together, dynamically fetches the correct subitem board, and sends one comprehensive update to Monday.com.

flowchart TD
    A["Receive Zapier Inputs (Comma-separated)"] --> B["Build Product Lookup Map"]
    B --> C["Fetch Subitem Board ID from Monday.com"]
    C --> D["Construct Batched GraphQL Mutation"]
    D --> E["Execute Single API Call"]
    E --> F["Generate Diagnostic Output"]

Configuration Guide

To implement this in your workflow, you will need to configure a Code by Zapier (Run JavaScript) step.

1. 1

   Configure Input Data

   In your Zapier Code step, map the following keys in the Input Data section. Ensure the values coming from previous steps are comma-separated strings.

   Input Key	Description
   mondayApiToken	Your Monday.com API v2 Token.
   teamMember	The default team member to assign (if not locked).
   itemsToUpdate	Comma-separated list of Monday subitem IDs.
   productsToUpdate	Comma-separated list of Product IDs.
   productsPriceUpdate	Comma-separated list of prices.
   dbProductIds	Database product IDs (used as the lookup key).
   dbQboIds	QuickBooks Online IDs.
   dbQBCategory	QuickBooks Categories.
   dbSpecialAction	Special action labels.
   dbTitleCodes	Title codes for the line items.
   dbTitleOrders	Title order numbers.
   dbTimeCalcs	Duration/time calculations.
   dbTimeCalcCodes	Time calculation codes.
   dbLockTeamMembers	Lock status for team member assignment.

2. 2

   Add the JavaScript Code

   Copy and paste the batched mutation script into the Code field.

   Check your Column IDs
   The code below uses specific Monday.com column IDs (e.g., text_Mjj2AaAS, status_mkkaxp21). You must update these column IDs to match the actual column IDs on your Monday.com subitem board.

   const MONDAY_API_TOKEN = inputData.mondayApiToken;
   const teamMember = inputData.teamMember || "";
   
   // Helper: split comma-separated string
   const split = function(str) {
     return str ? str.split(",").map(function(x) { return x.trim(); }).filter(Boolean) : [];
   };
   
   // Parse items to update
   const itemsToUpdate       = split(inputData.itemsToUpdate);
   const productsToUpdate    = split(inputData.productsToUpdate);
   const productsPriceUpdate = split(inputData.productsPriceUpdate);
   
   if (itemsToUpdate.length === 0) {
     output = { Status: "NothingToUpdate", TotalProcessed: 0 };
     return;
   }
   
   // Build Items Database lookup map
   const dbProductIds      = split(inputData.dbProductIds);
   const dbQboIds          = split(inputData.dbQboIds);
   const dbQBCategory      = split(inputData.dbQBCategory);
   const dbSpecialAction   = split(inputData.dbSpecialAction);
   const dbTitleCodes      = split(inputData.dbTitleCodes);
   const dbTitleOrders     = split(inputData.dbTitleOrders);
   const dbTimeCalcs       = split(inputData.dbTimeCalcs);
   const dbDefaultMembers  = split(inputData.dbDefaultMembers);
   const dbLockTeamMembers = split(inputData.dbLockTeamMembers);
   const dbTimeCalcCodes   = split(inputData.dbTimeCalcCodes);
   
   const itemsDB = {};
   dbProductIds.forEach(function(id, i) {
     itemsDB[id] = {
       qboId:          dbQboIds[i]          || "",
       qbCategory:     dbQBCategory[i]      || "",
       specialAction:  dbSpecialAction[i]   || "",
       titleCode:      dbTitleCodes[i]      || "",
       titleOrder:     dbTitleOrders[i]     || "",
       timeCalc:       dbTimeCalcs[i]       || "",
       timeCalcCode:   dbTimeCalcCodes[i]   || "",
       defaultMember:  dbDefaultMembers[i]  || "",
       lockTeamMember: dbLockTeamMembers[i] || ""
     };
   });
   
   // Resolve subitem board ID from the first subitem
   const boardQuery = "{ items(ids: [" + itemsToUpdate[0] + "]) { board { id } } }";
   const boardRes = await fetch("https://api.monday.com/v2", {
     method: "POST",
     headers: {
       "Content-Type":  "application/json",
       "Authorization": MONDAY_API_TOKEN,
       "API-Version":   "2024-01"
     },
     body: JSON.stringify({ query: boardQuery })
   });
   const boardData = await boardRes.json();
   const boardItems = boardData.data && boardData.data.items ? boardData.data.items : [];
   const SUBITEM_BOARD_ID = boardItems[0] && boardItems[0].board ? boardItems[0].board.id : null;
   
   if (!SUBITEM_BOARD_ID) throw new Error("Could not resolve subitem board ID from item: " + itemsToUpdate[0]);
   
   // Build batched mutation
   const mutationParts = [];
   const results       = [];
   
   for (let i = 0; i < itemsToUpdate.length; i++) {
     const subitemId = itemsToUpdate[i];
     const productId = productsToUpdate[i];
     const price     = productsPriceUpdate[i] || "";
     const dbItem    = itemsDB[productId] || {};
     const foundInDB = Object.prototype.hasOwnProperty.call(itemsDB, productId);
   
     // Business Logic: Suppress title columns if order > 900
     const rawTitleOrder      = parseFloat(dbItem.titleOrder) || 0;
     const titleCode          = rawTitleOrder > 900 ? "" : (dbItem.titleCode    || "");
     const titleOrder         = rawTitleOrder > 900 ? "" : (dbItem.titleOrder   || "");
     const timeCalcCode       = rawTitleOrder > 900 ? "" : (dbItem.timeCalcCode || "");
     const titleParsingOutput = titleCode && titleOrder ? titleCode + "-" + titleOrder : "";
   
     // Build column values (Update column IDs here to match your board)
     const cols = {};
     if (productId)             cols["text_Mjj2AaAS"]    = productId;
     if (price)                 cols["text_Mjj2CDRz"]    = price;
     if (dbItem.qboId)          cols["text_mkkq88hk"]    = dbItem.qboId;
     if (dbItem.qbCategory)     cols["status_mkkaxp21"]  = { label: dbItem.qbCategory };
     if (dbItem.specialAction)  cols["color_mkx2z43z"]   = { label: dbItem.specialAction };
     if (titleOrder)            cols["numbers_mkkw8n33"] = parseFloat(titleOrder) || 0;
     if (titleOrder)            cols["text_Mjj2A3O6"]    = titleOrder;
     if (titleCode)             cols["text_Mjj2G5AI"]    = titleCode;
     if (timeCalcCode)          cols["text_mkx8k859"]    = timeCalcCode;
     if (dbItem.lockTeamMember) cols["color_mkwdgmb0"]   = { label: dbItem.lockTeamMember };
     if (titleParsingOutput)    cols["text_Mjj2o8qB"]    = titleParsingOutput;
     if (dbItem.timeCalc)       cols["color_mkx8mezg"]   = { label: dbItem.timeCalc };
     
     // Assign team member unless locked
     if (dbItem.lockTeamMember !== "Locked" && teamMember) {
         cols["color_mkszrf28"] = { label: teamMember };
     }
   
     const colStr = JSON.stringify(JSON.stringify(cols));
     const alias  = "item_" + i;
   
     // Add to batch
     mutationParts.push(
       alias + ": change_multiple_column_values(board_id: " + SUBITEM_BOARD_ID + ", item_id: " + subitemId + ", column_values: " + colStr + ") { id }"
     );
   
     // Store diagnostics
     results.push({
       subitemId: subitemId,
       productId: productId,
       foundInDB: foundInDB,
       rawTitleOrder: rawTitleOrder,
       titleSuppressed: rawTitleOrder > 900,
       qboId: dbItem.qboId || "(MISSING)",
       qbCategory: dbItem.qbCategory || "(MISSING)",
       specialAction: dbItem.specialAction || "(MISSING)"
     });
   }
   
   // Execute single batched API call
   const batchMutation = "mutation { " + mutationParts.join("\n") + " }";
   
   const response = await fetch("https://api.monday.com/v2", {
     method: "POST",
     headers: {
       "Content-Type":  "application/json",
       "Authorization": MONDAY_API_TOKEN,
       "API-Version":   "2024-01"
     },
     body: JSON.stringify({ query: batchMutation })
   });
   
   const data = await response.json();
   if (data.errors) throw new Error("Monday API error: " + JSON.stringify(data.errors));
   
   // Diagnostic Output Generation
   const missingFromDB = results.filter(function(r) { return !r.foundInDB; });
   const missingQbo = results.filter(function(r) { return r.qboId === "(MISSING)"; });
   
   output = {
     TotalProcessed: results.length,
     Status: "Completed",
     MissingFromDB_Count: missingFromDB.length,
     MissingFromDB_Ids: missingFromDB.map(function(r) { return r.productId; }).join(", ") || "(none)",
     MissingQbo_Count: missingQbo.length,
     MissingQbo_Ids: missingQbo.map(function(r) { return r.productId; }).join(", ") || "(none)"
   };

3. 3

   Review Diagnostic Outputs

   The script outputs a diagnostic summary instead of raw API responses. You can use these output fields in subsequent Zapier steps (like sending a Slack alert if MissingFromDB_Count is greater than 0) to ensure data integrity.

Built-in Business Rules

The script includes specific business logic to handle edge cases automatically during the update process.