How to Extract Invoice Data and Generate a PDF Report with an API - Recipes

Request

# Step 1: Extract invoice data
EXTRACTION=$(curl -s -X POST https://api.iterationlayer.com/document-extraction/v1/extract \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "files": [
      {
        "type": "url",
        "name": "invoice-2026-0412.pdf",
        "url": "https://example.com/invoices/invoice-2026-0412.pdf"
      }
    ],
    "schema": {
      "fields": [
        { "name": "invoice_number", "type": "TEXT", "description": "Invoice number or identifier" },
        { "name": "vendor_name", "type": "TEXT", "description": "Name of the vendor or supplier" },
        { "name": "invoice_date", "type": "DATE", "description": "Date the invoice was issued" },
        { "name": "total_amount", "type": "CURRENCY_AMOUNT", "description": "Total amount due on the invoice" },
        {
          "name": "line_items",
          "type": "ARRAY",
          "description": "Individual line items on the invoice",
          "item_schema": {
            "fields": [
              { "name": "item_description", "type": "TEXT", "description": "Description of the item or service" },
              { "name": "amount", "type": "CURRENCY_AMOUNT", "description": "Amount for this line item" }
            ]
          }
        }
      ]
    }
  }')

# Step 2: Generate a PDF report from the extracted invoice data
curl -X POST https://api.iterationlayer.com/document-generation/v1/generate \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "format": "pdf",
    "document": {
      "metadata": {
        "title": "Invoice Summary — INV-2026-0412",
        "author": "Accounts Payable"
      },
      "page": {
        "size": { "preset": "A4" },
        "margins": {
          "top_in_pt": 54,
          "right_in_pt": 54,
          "bottom_in_pt": 54,
          "left_in_pt": 54
        }
      },
      "content": [
        { "type": "headline", "level": "h1", "text": "Invoice Summary — INV-2026-0412" },
        {
          "type": "paragraph",
          "runs": [
            { "text": "Vendor: ", "font_weight": "bold" },
            { "text": "Pinnacle Office Supplies Ltd.\n" },
            { "text": "Invoice Date: ", "font_weight": "bold" },
            { "text": "2026-03-28" }
          ]
        },
        { "type": "separator" },
        { "type": "headline", "level": "h2", "text": "Line Items" },
        {
          "type": "table",
          "headers": [
            { "text": "Description" },
            { "text": "Amount" }
          ],
          "rows": [
            [
              { "text": "A4 Copy Paper (10 reams)" },
              { "text": "$84.50" }
            ],
            [
              { "text": "Black Ink Cartridges (6-pack)" },
              { "text": "$137.94" }
            ],
            [
              { "text": "Ergonomic Desk Chair" },
              { "text": "$449.00" }
            ],
            [
              { "text": "Monitor Riser Stand" },
              { "text": "$62.00" }
            ]
          ]
        },
        { "type": "separator" },
        {
          "type": "paragraph",
          "runs": [
            { "text": "Total Amount Due: $733.44", "font_weight": "bold" }
          ]
        }
      ]
    }
  }'

Response

{
  "success": true,
  "data": {
    "buffer": "JVBERi0xLjQK...",
    "mime_type": "application/pdf"
  }
}

Request

import { IterationLayer } from "iterationlayer";
const client = new IterationLayer({ apiKey: "YOUR_API_KEY" });

// Step 1: Extract invoice data
const extraction = await client.extract({
  files: [
    {
      type: "url",
      name: "invoice-2026-0412.pdf",
      url: "https://example.com/invoices/invoice-2026-0412.pdf",
    },
  ],
  schema: {
    fields: [
      {
        name: "invoice_number",
        type: "TEXT",
        description: "Invoice number or identifier",
      },
      {
        name: "vendor_name",
        type: "TEXT",
        description: "Name of the vendor or supplier",
      },
      {
        name: "invoice_date",
        type: "DATE",
        description: "Date the invoice was issued",
      },
      {
        name: "total_amount",
        type: "CURRENCY_AMOUNT",
        description: "Total amount due on the invoice",
      },
      {
        name: "line_items",
        type: "ARRAY",
        description: "Individual line items on the invoice",
        item_schema: {
          fields: [
            {
              name: "item_description",
              type: "TEXT",
              description: "Description of the item or service",
            },
            {
              name: "amount",
              type: "CURRENCY_AMOUNT",
              description: "Amount for this line item",
            },
          ],
        },
      },
    ],
  },
});

const invoiceNumber = String(extraction["invoice_number"].value);
const vendorName = String(extraction["vendor_name"].value);
const invoiceDate = String(extraction["invoice_date"].value);
const totalAmount = String(extraction["total_amount"].value);
const lineItems = extraction["line_items"].value as Array<
  Record<string, { value: unknown }>
>;

// Step 2: Generate a PDF report from the extracted invoice data
const report = await client.generateDocument({
  format: "pdf",
  document: {
    metadata: {
      title: `Invoice Summary — ${invoiceNumber}`,
      author: "Accounts Payable",
    },
    page: {
      size: { preset: "A4" },
      margins: {
        top_in_pt: 54,
        right_in_pt: 54,
        bottom_in_pt: 54,
        left_in_pt: 54,
      },
    },
    content: [
      {
        type: "headline",
        level: "h1",
        text: `Invoice Summary — ${invoiceNumber}`,
      },
      {
        type: "paragraph",
        runs: [
          { text: "Vendor: ", font_weight: "bold" },
          { text: `${vendorName}\n` },
          { text: "Invoice Date: ", font_weight: "bold" },
          { text: invoiceDate },
        ],
      },
      { type: "separator" },
      { type: "headline", level: "h2", text: "Line Items" },
      {
        type: "table",
        headers: [{ text: "Description" }, { text: "Amount" }],
        rows: lineItems.map((item) => [
          { text: String(item["item_description"].value) },
          { text: String(item["amount"].value) },
        ]),
      },
      { type: "separator" },
      {
        type: "paragraph",
        runs: [
          { text: `Total Amount Due: ${totalAmount}`, font_weight: "bold" },
        ],
      },
    ],
  },
});

Response

{
  "success": true,
  "data": {
    "buffer": "JVBERi0xLjQK...",
    "mime_type": "application/pdf"
  }
}

Request

from iterationlayer import IterationLayer
client = IterationLayer(api_key="YOUR_API_KEY")

# Step 1: Extract invoice data
extraction = client.extract(
    files=[
        {
            "type": "url",
            "name": "invoice-2026-0412.pdf",
            "url": "https://example.com/invoices/invoice-2026-0412.pdf",
        }
    ],
    schema={
        "fields": [
            {"name": "invoice_number", "type": "TEXT", "description": "Invoice number or identifier"},
            {"name": "vendor_name", "type": "TEXT", "description": "Name of the vendor or supplier"},
            {"name": "invoice_date", "type": "DATE", "description": "Date the invoice was issued"},
            {"name": "total_amount", "type": "CURRENCY_AMOUNT", "description": "Total amount due on the invoice"},
            {
                "name": "line_items",
                "type": "ARRAY",
                "description": "Individual line items on the invoice",
                "item_schema": {
                    "fields": [
                        {"name": "item_description", "type": "TEXT", "description": "Description of the item or service"},
                        {"name": "amount", "type": "CURRENCY_AMOUNT", "description": "Amount for this line item"},
                    ]
                },
            },
        ]
    },
)

invoice_number = extraction["invoice_number"]["value"]
vendor_name = extraction["vendor_name"]["value"]
invoice_date = extraction["invoice_date"]["value"]
total_amount = extraction["total_amount"]["value"]
line_items = extraction["line_items"]["value"]

# Step 2: Generate a PDF report from the extracted invoice data
report = client.generate_document(
    format="pdf",
    document={
        "metadata": {
            "title": f"Invoice Summary — {invoice_number}",
            "author": "Accounts Payable",
        },
        "page": {
            "size": {"preset": "A4"},
            "margins": {
                "top_in_pt": 54,
                "right_in_pt": 54,
                "bottom_in_pt": 54,
                "left_in_pt": 54,
            },
        },
        "content": [
            {"type": "headline", "level": "h1", "text": f"Invoice Summary — {invoice_number}"},
            {
                "type": "paragraph",
                "runs": [
                    {"text": "Vendor: ", "font_weight": "bold"},
                    {"text": f"{vendor_name}\n"},
                    {"text": "Invoice Date: ", "font_weight": "bold"},
                    {"text": invoice_date},
                ],
            },
            {"type": "separator"},
            {"type": "headline", "level": "h2", "text": "Line Items"},
            {
                "type": "table",
                "headers": [
                    {"text": "Description"},
                    {"text": "Amount"},
                ],
                "rows": [
                    [
                        {"text": item["item_description"]["value"]},
                        {"text": str(item["amount"]["value"])},
                    ]
                    for item in line_items
                ],
            },
            {"type": "separator"},
            {
                "type": "paragraph",
                "runs": [{"text": f"Total Amount Due: {total_amount}", "font_weight": "bold"}],
            },
        ],
    },
)

Response

{
  "success": true,
  "data": {
    "buffer": "JVBERi0xLjQK...",
    "mime_type": "application/pdf"
  }
}

Request

package main

import (
    "fmt"

    il "github.com/iterationlayer/sdk-go"
)

func main() {
    client := il.NewClient("YOUR_API_KEY")

    // Step 1: Extract invoice data
    extraction, err := client.Extract(il.ExtractRequest{
        Files: []il.FileInput{
            il.NewFileFromURL("invoice-2026-0412.pdf", "https://example.com/invoices/invoice-2026-0412.pdf"),
        },
        Schema: il.ExtractionSchema{
            "invoice_number": il.NewTextFieldConfig("invoice_number", "Invoice number or identifier"),
            "vendor_name":    il.NewTextFieldConfig("vendor_name", "Name of the vendor or supplier"),
            "invoice_date":   il.NewDateFieldConfig("invoice_date", "Date the invoice was issued"),
            "total_amount":   il.NewCurrencyAmountFieldConfig("total_amount", "Total amount due on the invoice"),
            "line_items": il.NewArrayFieldConfig(
                "line_items",
                "Individual line items on the invoice",
                []il.FieldConfig{
                    il.NewTextFieldConfig("item_description", "Description of the item or service"),
                    il.NewCurrencyAmountFieldConfig("amount", "Amount for this line item"),
                },
            ),
        },
    })
    if err != nil {
        panic(err)
    }

    invoiceNumber := fmt.Sprintf("%v", (*extraction)["invoice_number"].Value)
    vendorName := fmt.Sprintf("%v", (*extraction)["vendor_name"].Value)
    invoiceDate := fmt.Sprintf("%v", (*extraction)["invoice_date"].Value)
    totalAmount := fmt.Sprintf("%v", (*extraction)["total_amount"].Value)

    // Step 2: Generate a PDF report from the extracted invoice data
    _, err = client.GenerateDocument(il.GenerateDocumentRequest{
        Format: "pdf",
        Document: il.DocumentDefinition{
            Metadata: il.DocumentMetadata{
                Title:  "Invoice Summary — " + invoiceNumber,
                Author: "Accounts Payable",
            },
            Page: il.DocumentPage{
                Size:    il.DocPageSize{Preset: "A4"},
                Margins: il.DocMargins{TopInPt: 54, RightInPt: 54, BottomInPt: 54, LeftInPt: 54},
            },
            Content: []il.ContentBlock{
                il.ContentBlock{"type": "headline", "level": "h1", "text": "Invoice Summary — " + invoiceNumber},
                il.ContentBlock{
                    "type": "paragraph",
                    "runs": []map[string]string{
                        {"text": "Vendor: ", "font_weight": "bold"},
                        {"text": vendorName + "\n"},
                        {"text": "Invoice Date: ", "font_weight": "bold"},
                        {"text": invoiceDate},
                    },
                },
                il.ContentBlock{"type": "separator"},
                il.ContentBlock{"type": "headline", "level": "h2", "text": "Line Items"},
                il.ContentBlock{
                    "type": "table",
                    "headers": []map[string]string{
                        {"text": "Description"},
                        {"text": "Amount"},
                    },
                    "rows": [][]map[string]string{
                        {{"text": "A4 Copy Paper (10 reams)"}, {"text": "$84.50"}},
                        {{"text": "Black Ink Cartridges (6-pack)"}, {"text": "$137.94"}},
                        {{"text": "Ergonomic Desk Chair"}, {"text": "$449.00"}},
                        {{"text": "Monitor Riser Stand"}, {"text": "$62.00"}},
                    },
                },
                il.ContentBlock{"type": "separator"},
                il.ContentBlock{
                    "type": "paragraph",
                    "runs": []map[string]string{{"text": "Total Amount Due: " + totalAmount, "font_weight": "bold"}},
                },
            },
        },
    })
    if err != nil {
        panic(err)
    }
}

Response

{
  "success": true,
  "data": {
    "buffer": "JVBERi0xLjQK...",
    "mime_type": "application/pdf"
  }
}

Template

{
  "name": "Invoice to PDF Report",
  "nodes": [
    {
      "parameters": {
        "content": "## Invoice to PDF Report\n\nFinance teams and invoice processing platforms use this recipe to automate the extract-to-report pipeline. Upload an invoice, extract structured data with confidence scores, and generate a branded PDF summary \u2014 all through two API calls.\n\n**Note:** This workflow uses the Iteration Layer community node (`n8n-nodes-iterationlayer`). Install it via Settings > Community Nodes before importing. Self-hosted n8n only.",
        "height": 280,
        "width": 500,
        "color": 2
      },
      "type": "n8n-nodes-base.stickyNote",
      "typeVersion": 1,
      "position": [
        200,
        40
      ],
      "id": "cb1571ce-e625-45bf-9316-2617d43d6880",
      "name": "Overview"
    },
    {
      "parameters": {
        "content": "### Step 1: Extract Invoice Data\nResource: **Document Extraction**\n\nConfigure the Document Extraction parameters below, then connect your credentials.",
        "height": 160,
        "width": 300,
        "color": 6
      },
      "type": "n8n-nodes-base.stickyNote",
      "typeVersion": 1,
      "position": [
        475,
        100
      ],
      "id": "f226bc1b-1ad5-4dad-9e7f-d4245823f4d4",
      "name": "Step 1 Note"
    },
    {
      "parameters": {
        "content": "### Step 2: Generate PDF Report\nResource: **Document Generation**\n\nConfigure the Document Generation parameters below, then connect your credentials.",
        "height": 160,
        "width": 300,
        "color": 6
      },
      "type": "n8n-nodes-base.stickyNote",
      "typeVersion": 1,
      "position": [
        725,
        100
      ],
      "id": "b2f28ece-0a45-4498-86de-232f2763fce4",
      "name": "Step 2 Note"
    },
    {
      "parameters": {},
      "type": "n8n-nodes-base.manualTrigger",
      "typeVersion": 1,
      "position": [
        250,
        300
      ],
      "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
      "name": "Manual Trigger"
    },
    {
      "parameters": {
        "resource": "documentExtraction",
        "schemaInputMode": "rawJson",
        "schemaJson": "[\n  {\n    \"name\": \"invoice_number\",\n    \"type\": \"TEXT\",\n    \"description\": \"The unique invoice identifier\"\n  },\n  {\n    \"name\": \"vendor_name\",\n    \"type\": \"TEXT\",\n    \"description\": \"Name of the vendor or supplier\"\n  },\n  {\n    \"name\": \"invoice_date\",\n    \"type\": \"DATE\",\n    \"description\": \"Date the invoice was issued\"\n  },\n  {\n    \"name\": \"line_items\",\n    \"type\": \"ARRAY\",\n    \"description\": \"List of line items on the invoice\",\n    \"children\": [\n      {\n        \"name\": \"item_description\",\n        \"type\": \"TEXT\",\n        \"description\": \"Description of the line item\"\n      },\n      {\n        \"name\": \"amount\",\n        \"type\": \"CURRENCY_AMOUNT\",\n        \"description\": \"Amount for this line item\"\n      }\n    ]\n  },\n  {\n    \"name\": \"total_amount\",\n    \"type\": \"CURRENCY_AMOUNT\",\n    \"description\": \"Total invoice amount\"\n  }\n]",
        "files": {
          "fileValues": [
            {
              "inputMode": "url",
              "fileUrl": "https://example.com/invoices/2026-001.pdf"
            }
          ]
        }
      },
      "type": "n8n-nodes-iterationlayer.iterationLayer",
      "typeVersion": 1,
      "position": [
        500,
        300
      ],
      "id": "b2c3d4e5-f6a7-8901-bcde-f23456789012",
      "name": "Extract Invoice Data",
      "credentials": {
        "iterationLayerApi": {
          "id": "1",
          "name": "Iteration Layer API"
        }
      }
    },
    {
      "parameters": {
        "resource": "documentGeneration",
        "format": "pdf",
        "documentJson": "{\n  \"pages\": [\n    {\n      \"width_in_pt\": 595,\n      \"height_in_pt\": 842,\n      \"blocks\": [\n        {\n          \"type\": \"paragraph\",\n          \"text\": \"Invoice Report\",\n          \"font_size_in_pt\": 28,\n          \"font_weight\": \"bold\",\n          \"color\": \"#1a1a1a\",\n          \"margin_top_in_pt\": 60,\n          \"margin_left_in_pt\": 50,\n          \"margin_right_in_pt\": 50\n        },\n        {\n          \"type\": \"paragraph\",\n          \"text\": \"Invoice #{{ $json.invoice_number }} \u2014 {{ $json.vendor_name }}\",\n          \"font_size_in_pt\": 14,\n          \"color\": \"#444444\",\n          \"margin_top_in_pt\": 20,\n          \"margin_left_in_pt\": 50,\n          \"margin_right_in_pt\": 50\n        },\n        {\n          \"type\": \"paragraph\",\n          \"text\": \"Date: {{ $json.invoice_date }}\",\n          \"font_size_in_pt\": 12,\n          \"color\": \"#666666\",\n          \"margin_top_in_pt\": 8,\n          \"margin_left_in_pt\": 50,\n          \"margin_right_in_pt\": 50\n        },\n        {\n          \"type\": \"table\",\n          \"margin_top_in_pt\": 30,\n          \"margin_left_in_pt\": 50,\n          \"margin_right_in_pt\": 50,\n          \"columns\": [\n            {\n              \"header\": \"Description\",\n              \"width_fraction\": 0.7\n            },\n            {\n              \"header\": \"Amount\",\n              \"width_fraction\": 0.3,\n              \"align\": \"right\"\n            }\n          ],\n          \"rows\": \"{{ $json.line_items }}\"\n        },\n        {\n          \"type\": \"paragraph\",\n          \"text\": \"Total: {{ $json.total_amount }}\",\n          \"font_size_in_pt\": 16,\n          \"font_weight\": \"bold\",\n          \"color\": \"#1a1a1a\",\n          \"margin_top_in_pt\": 20,\n          \"margin_left_in_pt\": 50,\n          \"margin_right_in_pt\": 50,\n          \"text_align\": \"right\"\n        }\n      ]\n    }\n  ]\n}"
      },
      "type": "n8n-nodes-iterationlayer.iterationLayer",
      "typeVersion": 1,
      "position": [
        750,
        300
      ],
      "id": "c3d4e5f6-a7b8-9012-cdef-345678901234",
      "name": "Generate PDF Report",
      "credentials": {
        "iterationLayerApi": {
          "id": "1",
          "name": "Iteration Layer API"
        }
      }
    }
  ],
  "connections": {
    "Manual Trigger": {
      "main": [
        [
          {
            "node": "Extract Invoice Data",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Extract Invoice Data": {
      "main": [
        [
          {
            "node": "Generate PDF Report",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "settings": {
    "executionOrder": "v1"
  }
}

Prompt

Extract data from the invoice at [file URL] using extract_document with fields for vendor name, invoice number, date, due date, line items (description, quantity, unit price, amount), subtotal, tax, and total. Then generate a formatted PDF summary using generate_document with the extracted data, including a header, invoice details, line items table, and totals.

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Invoice to PDF Report

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