Process Invoices from Gmail to Google Docs

The workflow JSON

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{
  "nodes": [
    {
      "parameters": {
        "pollTimes": {
          "item": [
            {
              "mode": "everyMinute",
              "minute": 5
            }
          ]
        },
        "filters": {
          "includeSpamTrash": false,
          "labelIds": [],
          "searchQuery": "has:attachment"
        },
        "options": {
          "dataPropertyAttachmentsPrefixName": "attachment_",
          "downloadAttachments": true,
          "simplify": true
        }
      },
      "id": "gmail-trigger",
      "name": "Gmail Trigger",
      "type": "n8n-nodes-base.gmailTrigger",
      "typeVersion": 1,
      "position": [
        250,
        300
      ],
      "notes": "Monitors inbox for emails with invoice attachments"
    },
    {
      "parameters": {
        "resource": "document",
        "operation": "extract",
        "inputType": "file",
        "binaryPropertyName": "attachment_0",
        "prompt": "Extract invoice data: invoice number, vendor name, invoice date (convert to YYYY-MM-DD), total amount, and all line items with descriptions, quantities, unit prices, and amounts.",
        "schema": "{\"type\":\"object\",\"properties\":{\"invoiceNumber\":{\"type\":\"string\"},\"vendorName\":{\"type\":\"string\"},\"invoiceDate\":{\"type\":\"string\"},\"totalAmount\":{\"type\":\"number\"},\"lineItems\":{\"type\":\"array\",\"items\":{\"type\":\"object\",\"properties\":{\"description\":{\"type\":\"string\"},\"quantity\":{\"type\":\"number\"},\"unitPrice\":{\"type\":\"number\"},\"amount\":{\"type\":\"number\"}},\"additionalProperties\":false}}},\"required\":[\"invoiceNumber\",\"totalAmount\"],\"additionalProperties\":false}",
        "useLLM": "smart"
      },
      "id": "extract-invoice",
      "name": "Extract structured data from a document",
      "type": "n8n-nodes-pdfvector.pdfVector",
      "typeVersion": 1,
      "position": [
        450,
        300
      ],
      "notes": "AI extracts invoice data with structured schema"
    },
    {
      "parameters": {
        "mode": "runOnceForEachItem",
        "jsCode": "const invoiceData = $json.data;\nconst formatCurrency = (amount) => `$${amount.toLocaleString('en-US', { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;\n\nlet markdown = `# Invoice ${invoiceData.invoiceNumber}\\n\\n`;\nmarkdown += `## Summary\\n\\n`;\nmarkdown += `- **Invoice Number**: ${invoiceData.invoiceNumber}\\n`;\nmarkdown += `- **Vendor**: ${invoiceData.vendorName}\\n`;\nmarkdown += `- **Date**: ${invoiceData.invoiceDate}\\n`;\nmarkdown += `- **Total Amount**: ${formatCurrency(invoiceData.totalAmount)}\\n\\n`;\nmarkdown += `## Line Items\\n\\n`;\n\nif (invoiceData.lineItems && invoiceData.lineItems.length > 0) {\n  markdown += `| Description | Quantity | Unit Price | Amount |\\n`;\n  markdown += `|-------------|----------|------------|--------|\\n`;\n  invoiceData.lineItems.forEach(item => {\n    markdown += `| ${item.description} | ${item.quantity} | ${formatCurrency(item.unitPrice)} | ${formatCurrency(item.amount)} |\\n`;\n  });\n}\n\nmarkdown += `\\n---\\n*Document generated automatically from invoice PDF*\\n`;\n\nreturn {\n  json: {\n    markdown: markdown,\n    documentTitle: `Invoice ${invoiceData.invoiceNumber} - ${invoiceData.vendorName}`,\n    invoiceNumber: invoiceData.invoiceNumber,\n    vendor: invoiceData.vendorName,\n    total: invoiceData.totalAmount\n  }\n};"
      },
      "id": "format-markdown",
      "name": "Format Invoice Markdown",
      "type": "n8n-nodes-base.code",
      "typeVersion": 2,
      "position": [
        650,
        300
      ],
      "notes": "Formats extracted data into beautiful markdown document"
    },
    {
      "parameters": {
        "operation": "create",
        "title": "={{ $json.documentTitle }}",
        "options": {}
      },
      "id": "create-doc",
      "name": "Create a document",
      "type": "n8n-nodes-base.googleDocs",
      "typeVersion": 1,
      "position": [
        850,
        300
      ],
      "notes": "Creates new Google Doc with invoice title"
    },
    {
      "parameters": {
        "operation": "update",
        "documentId": "={{ $json.id }}",
        "actionsUi": {
          "actionFields": [
            {
              "action": "insertText",
              "insertTextOptions": {
                "text": "={{ $('Format Invoice Markdown').item.json.markdown }}",
                "location": "body"
              }
            }
          ]
        }
      },
      "id": "update-doc",
      "name": "Update a document",
      "type": "n8n-nodes-base.googleDocs",
      "typeVersion": 2,
      "position": [
        1050,
        300
      ],
      "notes": "Adds formatted invoice content to the document"
    }
  ],
  "connections": {
    "Gmail Trigger": {
      "main": [
        [
          {
            "node": "Extract structured data from a document",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Extract structured data from a document": {
      "main": [
        [
          {
            "node": "Format Invoice Markdown",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Format Invoice Markdown": {
      "main": [
        [
          {
            "node": "Create a document",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Create a document": {
      "main": [
        [
          {
            "node": "Update a document",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "settings": {
    "executionOrder": "v1"
  }
}

About this workflow

Gmail-Invoice-Processor. Uses gmailTrigger, n8n-nodes-pdfvector, googleDocs. Event-driven trigger; 5 nodes.

Source: https://github.com/khanhduyvt0101/workflows/blob/0153ee2efc0f692c931b9bb4c2a04abf11756822/n8n-workflows/gmail-invoice-processor.json — original creator credit. Request a take-down →

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