If data has not the same keys and they are with dots in names i customized the to_internal_value function

serializers_mapping_keys_data.py

"""serializers"""
import logging
from collections import Mapping, OrderedDict
from typing import Dict

from django.core.exceptions import ValidationError as DjangoValidationError
from rest_framework import serializers
from rest_framework.exceptions import ValidationError
from rest_framework.fields import get_error_detail, set_value, SkipField
from rest_framework.settings import api_settings

from pricefetch.models import CurrencyExchangeRate  # Your model

logger = logging.getLogger(__name__)

class CurrencyExchangeRateSerializer(serializers.Serializer):
    """
    Base serializer for Alphavantage api.
    """
    from_currency_code = serializers.CharField(max_length=10)
    from_currency_name = serializers.CharField(max_length=50)
    to_currency_code = serializers.CharField(max_length=10)
    to_currency_name = serializers.CharField(max_length=50)
    exchange_rate = serializers.DecimalField(max_digits=20, decimal_places=10)
    last_refreshed = serializers.DateTimeField()
    time_zone = serializers.CharField(max_length=10)
    bid_price = serializers.DecimalField(max_digits=20, decimal_places=10)
    ask_price = serializers.DecimalField(max_digits=20, decimal_places=10)

    def to_internal_value(self, data: Dict):
        """
        Rewriting base function for mapping alphavantage dict keys and model fields.
        """
        mapping_dict = {
            'from_currency_code': '1. From_Currency Code',
            'from_currency_name': '2. From_Currency Name',
            'to_currency_code': '3. To_Currency Code',
            'to_currency_name': '4. To_Currency Name',
            'exchange_rate': '5. Exchange Rate',
            'last_refreshed': '6. Last Refreshed',
            'time_zone': '7. Time Zone',
            'bid_price': '8. Bid Price',
            'ask_price': '9. Ask Price'
        }
        if not isinstance(data, Mapping):
            message = self.error_messages['invalid'].format(datatype=type(data).__name__)
            raise ValidationError({api_settings.NON_FIELD_ERRORS_KEY: [message]
                                   }, code='invalid')

        ret = OrderedDict()
        errors = OrderedDict()
        fields = self._writable_fields

        for field in fields:
            validate_method = getattr(self, 'validate_' + field.field_name, None)
            primitive_value = data.get(mapping_dict[field.field_name])  # here is mapping model keys with alphavantage api
            try:
                validated_value = field.run_validation(primitive_value)
                if validate_method is not None:
                    validated_value = validate_method(validated_value)
            except ValidationError as exc:
                errors[field.field_name] = exc.detail
            except DjangoValidationError as exc:
                errors[field.field_name] = get_error_detail(exc)
            except SkipField:
                pass
            else:
                set_value(ret, [field.field_name], validated_value)  # set_value takes keys in list.

        if errors:
            raise ValidationError(errors)

        return ret

    def create(self, validated_data: Dict) -> CurrencyExchangeRate:
        """
        Saving model instance.
        :param validated_data:
        :type validated_data:
        :return:
        :rtype:
        """
        return CurrencyExchangeRate.objects.create(**validated_data)
    
"""
Example of using serializer with not matching keys in data.
>>> class D(serializers.Serializer):
...     name = serializers.CharField(max_length=20, source='wtf1 wtf2 wtf3')
...     sername = serializers.CharField(max_length=12)
data = {'wtf1 wtf2 wtf3': "here is", 'sername': 'Hello'}
>>> serializer = D(data)
>>> serializer_main = D(data=serializer.data)
>>> serializer_main.is_valid()               
True
>>> serializer_main.data 
{'name': 'here is'}
Example of using serializer with key where you have dot
 data = {'wtf1 wtf2. wtf3': "here is"}        
>>> class D(serializers.Serializer):                             
...     name = serializers.CharField(max_length=20, source='wtf1 wtf2. wtf3')
...     sername = serializers.CharField(max_length=12)
... 
>>> serializer = D(data)
>>> serializer.data
Traceback (most recent call last):
  File "/home/user/PycharmProjects/pricefetch/.venv/lib/python3.8/site-packages/rest_framework/fields.py", line 457, in get_attribute
    return get_attribute(instance, self.source_attrs)
  File "/home/user/PycharmProjects/pricefetch/.venv/lib/python3.8/site-packages/rest_framework/fields.py", line 95, in get_attribute
    instance = instance[attr]
KeyError: 'wtf1 wtf2'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/user/PycharmProjects/pricefetch/.venv/lib/python3.8/site-packages/rest_framework/serializers.py", line 548, in data
    ret = super().data
  File "/home/user/PycharmProjects/pricefetch/.venv/lib/python3.8/site-packages/rest_framework/serializers.py", line 246, in data
    self._data = self.to_representation(self.instance)
  File "/home/user/PycharmProjects/pricefetch/.venv/lib/python3.8/site-packages/rest_framework/serializers.py", line 502, in to_representation
    attribute = field.get_attribute(instance)
  File "/home/user/PycharmProjects/pricefetch/.venv/lib/python3.8/site-packages/rest_framework/fields.py", line 490, in get_attribute
    raise type(exc)(msg)
KeyError: "Got KeyError when attempting to get a value for field `name` on serializer `D`.\nThe serializer field might be named incorrectly and not match any attribute or key on the `dict` instance.\nOriginal exception text was: 'wtf1 wtf2'."

Because source attributes are parsed by dot
"""