decoders.py

import datetime
from medium.config import myapp
import re
import dateutil.parser

def pow_json_deserializer(dct):
        """
            converting json date stings to datetime.datetime for created_at and last_updated
            see: https://docs.python.org/3/library/json.html
            and: http://stackoverflow.com/questions/8793448/how-to-convert-to-a-python-datetime-object-with-json-loads
                    Nicola of course ;)
        """
        
        if "created_at" in dct:
            print("json deserializer found: created at: " + str(dct["created_at"]))
            #dct["created_at"]=datetime.datetime.strptime(dct["created_at"], myapp["date_format"])
        return dct

def pow_init_from_dict_deserializer(dct, schema, simple_conversion=False):
    """
        takes a dict with attributes and values 
        and (tries) to convert them to the specified types given in the schema
        Can be used in model.init_from_dict. (Which most often follows an init_from_json call)
                HTTP Request (data) => init_from_json(data) => dict(data) => init_from_dict(data, schema) => Model
        Reason:
            json data from ajax requests has for example dates as string but you most probably want datetime.
            list values come from html form text-fields as strings .. 
         
         simple_conversion = True tries to use simple logic to create 
                a little bit more advanced python data types.
                for example "a b c" will be model.attribute = "a b c".split(myapp["list_separator"])
                Mainly used for handling request from simple html form scaffolding 
    """
    for elem in dct:
        if elem in schema.keys():
            #print("converting: " + str(elem) + " : " + str(dct[elem]) + " => " + schema[elem]["type"] ) 
            if schema[elem]["type"].lower() == "datetime":
                if not isinstance(dct[elem], (datetime.datetime)):
                    #print(str(type(dct[elem])) + str(dct[elem]))
                    try:
                        # expecting primarily a string
                        dat = datetime.datetime.strptime(dct[elem], myapp["date_format"])
                        dat = dat.replace(tzinfo=None)
                        #print("date: str -> setting: {} to {}".format(elem, str(dct[elem])))
                        dct[elem]=dat
                    except Exception as e:
                        # give dateutil a chance .. (99% good)
                        try:
                            #print("date: dateutil setting: {} to {}".format(elem, str(dct[elem])))
                            dat=dateutil.parser.parse(dct[elem])
                            dat=dat.replace(tzinfo=None)
                            dct[elem]=dat
                        except:
                            # last try with epoch int
                            try:
                                dat = datetime.datetime.fromtimestamp(dct[elem])
                                dat=dat.replace(tzinfo=None)
                                dct[elem]=dat
                            except Exception as e1:
                                print(elem + "->" +str(type(dct[elem])) + str(dct[elem]))
                                print("Pow Decoders Exception for field: " + elem)
                                raise e1
            elif schema[elem]["type"].lower() == "integer":
                if not isinstance(dct[elem], (int)):
                    try:
                        dct[elem] = int(dct[elem])
                    except Exception as e:
                        print(elem + "->" +
                              str(type(dct[elem])) + str(dct[elem]))
                        print("Exception for field: " + elem)
                        raise e
            elif schema[elem]["type"].lower() == "dict":
                if not isinstance(dct[elem], (dict)):
                    try:
                        import ast
                        if isinstance(dct[elem], (str)):
                            # see: https://stackoverflow.com/questions/988228/convert-a-string-representation-of-a-dictionary-to-a-dictionary
                            dct[elem] = ast.literal_eval(dct[elem])
                    except Exception as e:
                        raise e
            elif schema[elem]["type"].lower() == "boolean":
                if not isinstance(dct[elem], (bool)):
                    try:
                        if isinstance(dct[elem], (str)):
                            dct[elem] = int(dct[elem])
                        dct[elem] = bool(dct[elem])
                    except Exception as e:
                        raise e
            elif schema[elem]["type"].lower() == "string":
                if not isinstance(dct[elem], (str)):
                    try:
                        dct[elem] = str(dct[elem])
                    except Exception as e:
                        raise e
            elif schema[elem]["type"].lower() == "list":
                if not isinstance(dct[elem], (list)):
                    try:
                        if simple_conversion:
                            # split the given input with config.list_separator
                            dct[elem] = dct[elem].split(myapp["list_separator"])
                        else:
                            dct[elem] = list(dct[elem])
                    except Exception as e:
                        raise e
            elif schema[elem]["type"].lower() == "float":
                if not isinstance(dct[elem], (float)):
                    try:
                        dct[elem] = float(dct[elem])
                    except Exception as e:
                        raise e
            elif schema[elem]["type"].lower() == "set":
                if not isinstance(dct[elem], (set)):
                    try:
                        dct[elem] = set(dct[elem])
                    except Exception as e:
                        raise e
    return dct