Extract a json/dict from a string in Python

json_utils.py

import logging

logger = logging.getLogger(__name__)

def extract_json_from_string(text:str) -> dict:
    """Convert a text containing a JSON or python dict into a python dict. 

    :param str text:
    :raises ValueError: If the string does not contains a valid json
    :return dict: 
    """
    start_dict = text.find('{')
    end_dict   = text.rfind('}')

    # Check if dict boundaries are valid
    if start_dict == -1 or end_dict == -1:
        logger.warning(  'JSON wrong format : the string do not have opening or closing bracket. (missing "{" or "}")')
        raise ValueError('JSON wrong format : the string do not have opening or closing bracket. (missing "{" or "}")')
        
    dict_string = text[start_dict:end_dict+1]
    try:
        extracted_dict = eval(dict_string)
        logger.debug(f'Extracted JSON (`eval()`) : {extracted_dict}')
    except:
        try:
            import json
            extracted_dict = json.loads(dict_string)
            logger.debug(f'Extracted JSON (`json.loads()`) : {extracted_dict}')
        except Exception as e:
            logger.exception(f'Error during the conversion from a string of a dict to a python dict. dict_string : {dict_string}')
            raise ValueError(f'Error during the conversion from a string of a dict to a python dict. dict_string : {dict_string}')
    return extracted_dict

if __name__=="__main__":
    string_dict =   """
                    {
                        'f1': 'string here',
                        'f2': 1234,
                        'f3': None,
                        'f4': 'null'
                    }
                    """
    print(extract_json_from_string(string_dict))