本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 從表單文檔中提取鍵值對
<a name="examples-extract-kvp"></a>

以下 Python 範例示範如何從[Block](API_Block.md)儲存在地圖中的物件。塊對象從調用[AnalyzeDocument](API_AnalyzeDocument.md)。如需詳細資訊，請參閱 [表單數據（鍵值對）](how-it-works-kvp.md)。

您可以使用以下函數：
+ `get_kv_map`— 呼叫[AnalyzeDocument](API_AnalyzeDocument.md)，並將鍵和值塊對象存儲在地圖中。
+ `get_kv_relationship`和`find_value_block`— 從地圖構造鍵值關係。

**從表單檔中提取鍵-值對**

1. 設定您的環境。如需詳細資訊，請參閱 [先決條件](examples-blocks.md#examples-prerequisites)。

1. 將下列範本程式碼複製到名為的*textract\$1python\$1kv\$1parser.py*。

   ```
   import boto3
   import sys
   import re
   import json
   
   
   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
       client = boto3.client('textract')
       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 = {}
       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] = 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. 在命令提示中，輸入以下命令：Replace`file`取代為您要分析的檔案圖像檔案。

   ```
   textract_python_kv_parser.py file
   ```

1. 當系統提示時，輸入輸入文檔中的鍵。如果代碼檢測到密鑰，它將顯示密鑰的值。