> ## Documentation Index
> Fetch the complete documentation index at: https://docs-docflow.textin.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Basic Field Information

> Detailed explanation of field information structure and processing methods in document extraction

The document extraction feature identifies key field information in a document based on the fields configured for its file category.Each field includes a key-value pair and position coordinate information.

## Field Structure

Field information is located in `result.files[].data.fields[]`, with each field containing the following attributes:

* `key`: Field name (such as "Invoice Code", "Invoice Date", etc.)
* `value`: Field value (recognized text content)
* `position[]`: Position coordinate information of the field in the document; fields may span pages or lines, so an array is used

### Position Coordinate Structure

```json theme={null}
{
  "page": 0,           // Page number where the field is located
  "vertices": [        // Coordinates of four vertices [x1,y1,x2,y2,x3,y3,x4,y4]
    100, 200,          // Top-left corner
    300, 200,          // Top-right corner
    300, 250,          // Bottom-right corner
    100, 250           // Bottom-left corner
  ]
}
```

For detailed coordinate descriptions, please refer to the [Coordinate System](../03-parse/coordinate.mdx) documentation.

## Example Code

<CodeGroup>
  ```python Python expandable icon=python theme={null}
  import requests
  import json

  def extract_fields(workspace_id, batch_number, app_id, secret_code):
      """Extract field information from documents"""
      
      host = "https://docflow.textin.ai"
      url = "/api/app-api/sip/platform/v2/file/fetch"
      
      resp = requests.get(
          f"{host}{url}",
          params={
              "workspace_id": workspace_id, 
              "batch_number": batch_number
          },
          headers={
              "x-ti-app-id": app_id, 
              "x-ti-secret-code": secret_code
          },
          timeout=60,
      )
      
      if resp.status_code != 200:
          print(f"Request failed: {resp.status_code}")
          return None
      
      data = resp.json()
      
      for file in data.get("result", {}).get("files", []):
          print(f"File name: {file.get('name')}")
          print(f"Recognition status: {file.get('recognition_status')}")
          
          # Extract field information
          fields = file.get("data", {}).get("fields", [])
          if fields:
              print("\n=== Field Information ===")
              for field in fields:
                  key = field.get("key", "")
                  value = field.get("value", "")
                  positions = field.get("position", [])
                  
                  print(f"Field: {key}")
                  print(f"Value: {value}")
                  
                  # Display position information
                  for i, pos in enumerate(positions):
                      page = pos.get("page", 0)
                      vertices = pos.get("vertices", [])
                      print(f"  Position {i+1} (Page {page+1}): {vertices}")
                  print("-" * 30)
          else:
              print("No field information found")
      
      return data

  # Usage example
  if __name__ == "__main__":
      workspace_id = "<your-workspace-id>"
      batch_number = "<your-batch-number>"
      app_id = "<your-app-id>"
      secret_code = "<your-secret-code>"
      
      result = extract_fields(workspace_id, batch_number, app_id, secret_code)
  ```
</CodeGroup>

## Return Data Example

```json expandable theme={null}
{
  "code": 200,
  "result": {
    "files": [
      {
        "id": "202412190001",
        "name": "invoice.pdf",
        "recognition_status": 1,
        "data": {
          "fields": [
            {
              "key": "Invoice Code",
              "value": "3100231130",
              "position": [
                {
                  "page": 0,
                  "vertices": [100, 150, 200, 150, 200, 180, 100, 180]
                }
              ]
            },
            {
              "key": "Invoice Number",
              "value": "12345678",
              "position": [
                {
                  "page": 0,
                  "vertices": [250, 150, 320, 150, 320, 180, 250, 180]
                }
              ]
            },
            {
              "key": "Invoice Date",
              "value": "December 19, 2024",
              "position": [
                {
                  "page": 0,
                  "vertices": [400, 150, 500, 150, 500, 180, 400, 180]
                }
              ]
            },
            {
              "key": "Buyer Name",
              "value": "Shanghai XX Technology Co., Ltd.",
              "position": [
                {
                  "page": 0,
                  "vertices": [100, 250, 400, 250, 400, 280, 100, 280]
                }
              ]
            },
            {
              "key": "Amount",
              "value": "1000.00",
              "position": [
                {
                  "page": 0,
                  "vertices": [500, 350, 600, 350, 600, 380, 500, 380]
                }
              ]
            }
          ]
        }
      }
    ]
  }
}
```