Using regex with escaped characters crashes with "yaml.scanner.ScannerError: while scanning a double-quoted scalar"

[iTaybb]

When using classes with regexes, aiohttp-swagger attempts to convert these to patterns in the openapi v3 format.
If the regex got any escaped characters, such as \w, the code will crash:

Traceback (most recent call last):
  File "/c/git/app/rest/__init__.py", line 31, in setup_swagger  
    aiohttp_swagger.setup_swagger(app, api_version=__api_version__,
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/aiohttp_swagger/__init__.py", line 66, in setup_swagger
    swagger_info = generate_doc_from_each_end_point(
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/aiohttp_swagger/helpers/builders.py", line 129, in generate_doc_from_each_end_point
    swagger = yaml.full_load(swagger_base)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/__init__.py", line 142, in full_load
    return load(stream, FullLoader)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/__init__.py", line 114, in load
    return loader.get_single_data()
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/constructor.py", line 49, in get_single_data
    node = self.get_single_node()
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/composer.py", line 64, in compose_node
    if self.check_event(AliasEvent):
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/parser.py", 
line 98, in check_event
    self.current_event = self.state()
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/parser.py", 
line 449, in parse_block_mapping_value
    if not self.check_token(KeyToken, ValueToken, BlockEndToken):
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/scanner.py", line 251, in fetch_more_tokens
    return self.fetch_double()
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/scanner.py", line 655, in fetch_double
    self.fetch_flow_scalar(style='"')
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/scanner.py", line 666, in fetch_flow_scalar
    self.tokens.append(self.scan_flow_scalar(style))
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/scanner.py", line 1149, in scan_flow_scalar
    chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
  File "/home/itay/.pyenv/versions/3.9.5/lib/python3.9/site-packages/yaml/scanner.py", line 1223, in scan_flow_scalar_non_spaces
    raise ScannerError("while scanning a double-quoted scalar", start_mark,
yaml.scanner.ScannerError: while scanning a double-quoted scalar
  in "<unicode string>", line 272, column 26:
                    pattern: "^s3://[\w]+/"
                             ^
found unknown escape character 'w'
  in "<unicode string>", line 272, column 35:
                    pattern: "^s3://[\w]+/"

This happens because the openapi.yaml jinja manifest exports the pattern as:

s3_bucket_key:
                title: "S3 Bucket Key"
                pattern: "^s3://[\\w]+/"
                type: "string"

and causes an error, since \ in double quote is parsed as escape sequence by YAML.

The solution would probably be to use single quotes instead of double quotes, probably in the nesteddict2yaml function.

[iTaybb]

This is still relevant.

Fix using sed:
sed -i 's|" \\"" + str(value) + "\\"\\n"|" \\"" + str(value).replace("\\\\", "\\\\\\\\") + "\\"\\n"|g' $(python -c 'import os.path, aiohttp_swagger; print(os.path.dirname(aiohttp_swagger.__file__))')/helpers/builders.py