How to convert dictionary list to custom objects in Python

Question

I have a list which has some dictionaries to be bulk uploaded. I need to check if elements of list can be cast to a custom object(as below). Is there any elegant way to do it like type comparison?

This is my model

class CheckModel(object):

    def __init__(self,SerialNumber,UID, Guid = None,Date = None):
        self.SerialNumber = SerialNumber
        self.UID = UID
        self.Guid = str(uuid.uuid4()) if Guid is None else Guid
        self.Date = datetime.now().isoformat() if Date is None else Date

And this is my test data. How can I cast only first element(because first element is the only correct one.) of this list into CheckModel object?

test = [{
        "Guid":"d0c035a7-0e01-4a37-8fe9-251fb5633fc9",
        "SerialNumber":"1716154A",
        "UID":"F13BDB3B",
        "Date":"2019-12-03T13:50:19.882Z"

    },
    {
        "Guid":"d0585-0e01-4a47-8fe9-251245f33fc9",
        "SerialNumber":"1716154A",
        "Date":"2019-12-03T13:50:19.882Z"
    },
    {
        "Guid":"12414a7-0e01-4a47-8fe9-251245f33fc9",
        "SerialNumber":"1716154A",
        "UID":"F13BDB3B",
        "Date":"2019-12-03"
    }]

score 2 · Accepted Answer · answered May 06 '19 at 13:43

You can create a custom cleanup function and then use filter

Ex:

import datetime
import uuid

class CheckModel(object):

    def __init__(self,SerialNumber,UID, Guid = None,Date = None):
        self.SerialNumber = SerialNumber
        self.UID = UID
        self.Guid = str(uuid.uuid4()) if Guid is None else Guid
        self.Date = datetime.datetime.now().isoformat() if Date is None else Date

#Clean Up Function.             
def clean_data(data):
    if all(key in data for key in ("Guid", "SerialNumber", "UID", "Date")):
        try:
            datetime.datetime.strptime(data["Date"], "%Y-%m-%dT%H:%M:%S.%fZ")
            return True
        except:
            pass
    return False 


test = [{
        "Guid":"d0c035a7-0e01-4a37-8fe9-251fb5633fc9",
        "SerialNumber":"1716154A",
        "UID":"F13BDB3B",
        "Date":"2019-12-03T13:50:19.882Z"

    },
    {
        "Guid":"d0585-0e01-4a47-8fe9-251245f33fc9",
        "SerialNumber":"1716154A",
        "Date":"2019-12-03T13:50:19.882Z"
    },
    {
        "Guid":"12414a7-0e01-4a47-8fe9-251245f33fc9",
        "SerialNumber":"1716154A",
        "UID":"F13BDB3B",
        "Date":"2019-12-03"
    }]

model_data = [CheckModel(**data) for data in filter(clean_data, test)]
print(model_data)

Output:

[<__main__.CheckModel object at 0x0000000002F0AFD0>]

score 0 · Answer 2 · answered May 06 '19 at 13:35

0

As you already have an initializer for the CheckModel class you should be able to just pass the values from the dict to this function:

check_model = CheckModel(test[0]['SerialNumber'], test[0]['UID'], test[0]['Guid'], test[0]['Date'])

answered May 06 '19 at 13:35

Duck Hunt Duo

299
1
11

score 0 · Answer 3 · answered May 06 '19 at 13:36

If you just want the first one, you can use **kwargs to unpack a dictionary as a mapping into your __init__

some_object = CheckModel(**test[0])

However, this will only work if all of the keys are available as arguments of the function. This will raise an exception if you try this with test[1], since the UID arg will be missing

score 0 · Answer 4 · answered May 06 '19 at 13:38

Use **kwargs to pass the dictionary as an argument to the constructor, which will unpack the dictionary as a list of argument

In addition, I would suggest making UID=None since UID was missing in one of the dictionaries of the list. Below will parse all elements of list into the Class

import datetime as datetime

class CheckModel(object):

    #Made UID None since it is not present in one of the dictionaries
    def __init__(self,SerialNumber,UID=None, Guid = None,Date = None):
        self.SerialNumber = SerialNumber
        self.UID = UID
        self.Guid = str(uuid.uuid4()) if Guid is None else Guid
        self.Date = datetime.now().isoformat() if Date is None else Date

test = [{
        "Guid":"d0c035a7-0e01-4a37-8fe9-251fb5633fc9",
        "SerialNumber":"1716154A",
        "UID":"F13BDB3B",
        "Date":"2019-12-03T13:50:19.882Z"

    },
    {
        "Guid":"d0585-0e01-4a47-8fe9-251245f33fc9",
        "SerialNumber":"1716154A",
        "Date":"2019-12-03T13:50:19.882Z"
    },
    {
        "Guid":"12414a7-0e01-4a47-8fe9-251245f33fc9",
        "SerialNumber":"1716154A",
        "UID":"F13BDB3B",
        "Date":"2019-12-03"
    }]

models = []

for item in test:
    #Use **kwargs to pass dictionary as arguments to constructor
    models.append(CheckModel(**item))
print(models)

To just create the object of first item in the list, do

CheckModel(**test[0])

score 0 · Answer 5 · answered May 06 '19 at 13:39

This should give you access to the first element of the list and then you can parse out the dictionary as necessary.

elem = check_model[0]

# Use the get() function on a dictionary to get the value of key without 
# breaking the code if the key doesn't exist
guid = elem.get('Guid')
serial_number = elem.get('SerialNumber')
uid = elem.get('UID')
date = elem.get('Date')

instance = CheckModel(serial_number, uid, Guid=guid, Date=date)

# Do something with it
instance.do_something()

How to convert dictionary list to custom objects in Python

5 Answers5