# Extracting Key-Value Pairs from a Form Document
<a name="examples-extract-kvp"></a>

The following Python example shows how to extract key-value pairs in form documents from [Block](API_Block.md) objects that are stored in a map. Block objects are returned from a call to [AnalyzeDocument](API_AnalyzeDocument.md). For more information, see [Form Data (Key-Value Pairs)](how-it-works-kvp.md).

You use the following functions: 
+ `get_kv_map` – Calls [AnalyzeDocument](API_AnalyzeDocument.md), and stores the KEY and VALUE BLOCK objects in a map.
+ `get_kv_relationship` and `find_value_block` – Constructs the key-value relationships from the map.

**To extract key-value pairs from a form document**

1. Configure your environment. For more information, see [Prerequisites](examples-blocks.md#examples-prerequisites).

1. Save the following example code to a file named *textract\$1python\$1kv\$1parser.py*. In the function `get_kv_map`, replace `profile-name` with the name of a profile that can assume the role and `region` with the region in which you want to run the code.

   ```
   import boto3
   import sys
   import re
   import json
   from collections import defaultdict
   
   
   def get_kv_map(file_name):
       with open(file_name, 'rb') as file:
           img_test = file.read()
           bytes_test = bytearray(img_test)
           print('Image loaded', file_name)
   
       # process using image bytes
       session = boto3.Session(profile_name='profile-name')
       client = session.client('textract', region_name='region')
       response = client.analyze_document(Document={'Bytes': bytes_test}, FeatureTypes=['FORMS'])
   
       # Get the text blocks
       blocks = response['Blocks']
   
       # get key and value maps
       key_map = {}
       value_map = {}
       block_map = {}
       for block in blocks:
           block_id = block['Id']
           block_map[block_id] = block
           if block['BlockType'] == "KEY_VALUE_SET":
               if 'KEY' in block['EntityTypes']:
                   key_map[block_id] = block
               else:
                   value_map[block_id] = block
   
       return key_map, value_map, block_map
   
   
   def get_kv_relationship(key_map, value_map, block_map):
       kvs = defaultdict(list)
       for block_id, key_block in key_map.items():
           value_block = find_value_block(key_block, value_map)
           key = get_text(key_block, block_map)
           val = get_text(value_block, block_map)
           kvs[key].append(val)
       return kvs
   
   
   def find_value_block(key_block, value_map):
       for relationship in key_block['Relationships']:
           if relationship['Type'] == 'VALUE':
               for value_id in relationship['Ids']:
                   value_block = value_map[value_id]
       return value_block
   
   
   def get_text(result, blocks_map):
       text = ''
       if 'Relationships' in result:
           for relationship in result['Relationships']:
               if relationship['Type'] == 'CHILD':
                   for child_id in relationship['Ids']:
                       word = blocks_map[child_id]
                       if word['BlockType'] == 'WORD':
                           text += word['Text'] + ' '
                       if word['BlockType'] == 'SELECTION_ELEMENT':
                           if word['SelectionStatus'] == 'SELECTED':
                               text += 'X '
   
       return text
   
   
   def print_kvs(kvs):
       for key, value in kvs.items():
           print(key, ":", value)
   
   
   def search_value(kvs, search_key):
       for key, value in kvs.items():
           if re.search(search_key, key, re.IGNORECASE):
               return value
   
   
   def main(file_name):
       key_map, value_map, block_map = get_kv_map(file_name)
   
       # Get Key Value relationship
       kvs = get_kv_relationship(key_map, value_map, block_map)
       print("\n\n== FOUND KEY : VALUE pairs ===\n")
       print_kvs(kvs)
   
       # Start searching a key value
       while input('\n Do you want to search a value for a key? (enter "n" for exit) ') != 'n':
           search_key = input('\n Enter a search key:')
           print('The value is:', search_value(kvs, search_key))
   
   if __name__ == "__main__":
       file_name = sys.argv[1]
       main(file_name)
   ```

1. At the command prompt, enter the following command. Replace `file` with the document image file that you want to analyze.

   ```
   python textract_python_kv_parser.py file
   ```

1. When you're prompted, enter a key that's in the input document. If the code detects the key, it displays the key's value.