How Can I Append Unique URL Rows from One Google Sheet to Another in n8n?

Below is one approach to building your workflow:

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1. Get the URLs from Sheet1 and Sheet2

• Use two separate Google Sheets nodes with the Get Row(s) operation.
 - For Sheet1, fetch all rows (make sure the first row is treated as headers if needed).
 - For Sheet2, do the same to retrieve the list of URLs already present.

For more details on how to use the Get Row(s) operation, see the Google Sheets Get Row(s) documentation.

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2. Compare the Data

• Use a Function node (or IF node if possible) to loop through the URLs from Sheet1.
• In the function, compare each URL from Sheet1 against all URLs from Sheet2.
• For each URL not found in Sheet2, pass it on for insertion.

A brief outline of what the function might look like:

JSCopied
// n8n automatically combines incoming data items into an array "items"
// Assume the output of Sheet1 is in items and Sheet2 data has been stored in a variable (e.g. via Set/Function node beforehand)
// For example, let's assume you've stored Sheet2 URLs in "sheet2Urls" (an array of strings):

const sheet1Data = items.map(item => item.json.URL); // replace 'URL' with your actual field name
const sheet2Urls = $getWorkflowStaticData("global").sheet2Urls || []; // assuming you saved sheet2 URLs in static data

const newRows = [];

for (const item of items) {
  const url = item.json.URL;
  if (!sheet2Urls.includes(url)) {
    // URL not present in Sheet2, add the full row to newRows for later insertion.
    newRows.push(item.json);
  }
}

return newRows.map(row => ({ json: row }));

Note: How you store and reference Sheet2’s data will depend on your workflow setup. You might use an additional Function node (or Set node if applicable) to store that list.

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3. Append the New Rows to Sheet2

• Use the Google Sheets node with the Append Row operation to insert the new rows into Sheet2.
• Configure it to pick your spreadsheet by URL, ID, or from the list and choose the target sheet.

For more details on the Append Row operation, refer to the Google Sheets Append Row documentation.

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4. Authentication Troubleshooting

Since you mentioned authentication challenges:

• Double-check that you have created and selected your Google Sheets credentials correctly.
• Ensure that the OAuth scopes and token permissions are correctly set up.
• Look at the Google Sheets credentials docs and common issues section if you run into further errors.

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Putting It All Together

Your workflow might look like this:

1. Google Sheets node (Sheet1) – Fetch new data.
2. Google Sheets node (Sheet2) – Fetch existing URLs; store these in static data or pass them to a Function node.
3. Function node – Compare the two sets of URLs; output only rows with URLs that aren’t in Sheet2.
4. Google Sheets node (Sheet2 Append Row) – Append each new row to Sheet2.

This approach minimizes API calls while keeping the logic clear and maintainable.

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By following these steps, you’ll be able to compare and update your Google Sheets as needed. For more information about each operation and additional examples, please check the relevant sections of the documentation. If you need further guidance on specific node configurations, feel free to ask!