Handle recursively serializing a dataclasses as a dictionary.

ocpp/charge_point.py

@@ -4,8 +4,8 @@
 import re
 import time
 import uuid
-from dataclasses import asdict
-from typing import Dict, List, Union
+from dataclasses import Field, asdict, is_dataclass
+from typing import Any, Dict, List, Union, get_args, get_origin
 
 from ocpp.exceptions import NotImplementedError, NotSupportedError, OCPPError
 from ocpp.messages import Call, MessageType, unpack, validate_payload
@@ -69,6 +69,85 @@ def snake_to_camel_case(data):
     return data
 
 
+def _is_dataclass_instance(input: Any) -> bool:
+    """Verify if given `input` is a dataclass."""
+    return is_dataclass(input) and not isinstance(input, type)
+
+
+def _is_optional_field(field: Field) -> bool:
+    """Verify if given `field` allows `None` as value.
+
+    The fields `schema` and `host` on the following class would return `False`.
+    While the fields `post` and `query` return `True`.
+
+        @dataclass
+        class URL:
+            schema: str,
+            host: str,
+            post: Optional[str],
+            query: Union[None, str]
+
+    """
+    return get_origin(field.type) is Union and type(None) in get_args(field.type)
+
+
+def serialize_as_dict(dataclass, remove_empty_optional_fields: bool = True):
+    """Serialize the given `dataclass` as a `dict` recursively.
+
+
+    @dataclass
+    class StatusInfoType:
+        reason_code: str
+        additional_info: Optional[str] = None
+
+    with_additional_info = StatusInfoType(reason="Unknown",
+    additional_info="More details")
+
+    assert serialize_as_dict(with_additional_info) == {
+        'reason': 'Unknown',
+        'additional_info': 'More details',
+    }
+
+    without_additional_info = StatusInfoType(reason="Unknown")
+
+    assert serialize_as_dict(with_additional_info) == {
+        'reason': 'Unknown',
+        'additional_info': None,
+    }
+
+    assert serialize_as_dict(with_additional_info,
+    remove_empty_optional_fields) == {
+        'reason': 'Unknown',
+    }
+
+
+    """
+    serialized = asdict(dataclass)
+
+    for field in dataclass.__dataclass_fields__.values():
+        # Remove field from serialized output if the field is optional and
+        # `None`.
+        if (
+            remove_empty_optional_fields
+            and _is_optional_field(field)
+            and serialized[field.name] is None
+        ):
+            del serialized[field.name]
+            continue
+
+        value = getattr(dataclass, field.name)
+        if _is_dataclass_instance(value):
+            serialized[field.name] = serialize_as_dict(value)
+            continue
+
+        if isinstance(value, list):
+            for item in value:
+                if _is_dataclass_instance(item):
+                    serialized[field.name] = [serialize_as_dict(item)]
+
+    return snake_to_camel_case(serialized)
+
+
 def remove_nones(data: Union[List, Dict]) -> Union[List, Dict]:
     if isinstance(data, dict):
         return {k: remove_nones(v) for k, v in data.items() if v is not None}

pyproject.toml

@@ -33,6 +33,7 @@ classifiers = [
 [tool.poetry.dependencies]
 python = "^3.7"
 jsonschema = "^4.4.0"
+typing-extensions = "^4.0.0"
 
 [tool.poetry.dev-dependencies]
 # Starting from Python 3.8, asynctest is replaced with a unittest.mock.AsyncMock in standard library.

tests/test_charge_point.py

@@ -2,7 +2,12 @@
 
 import pytest
 
-from ocpp.charge_point import camel_to_snake_case, remove_nones, snake_to_camel_case
+from ocpp.charge_point import (
+    camel_to_snake_case,
+    remove_nones,
+    serialize_as_dict,
+    snake_to_camel_case,
+)
 from ocpp.routing import create_route_map, on
 from ocpp.v16.call import (
     BootNotificationPayload,
@@ -12,8 +17,14 @@
 from ocpp.v16.datatypes import MeterValue, SampledValue
 from ocpp.v16.enums import Action
 from ocpp.v20 import ChargePoint as cp
-from ocpp.v201.call import SetNetworkProfilePayload
-from ocpp.v201.datatypes import NetworkConnectionProfileType
+from ocpp.v201.call import GetVariablesPayload, SetNetworkProfilePayload
+from ocpp.v201.datatypes import (
+    ComponentType,
+    EVSEType,
+    GetVariableDataType,
+    NetworkConnectionProfileType,
+    VariableType,
+)
 from ocpp.v201.enums import OCPPInterfaceType, OCPPTransportType, OCPPVersionType
 
 
@@ -230,3 +241,33 @@ def test_remove_nones_with_list_of_strings():
     assert remove_nones(payload) == {
         "key": ["ClockAlignedDataInterval", "ConnectionTimeOut"]
     }
+
+
+def test_serialize_as_dict():
+    payload = GetVariablesPayload(
+        get_variable_data=[
+            GetVariableDataType(
+                component=ComponentType(
+                    name="Component",
+                    evse=EVSEType(id=1),
+                ),
+                variable=VariableType(name="Variable"),
+            )
+        ]
+    )
+
+    assert serialize_as_dict(payload) == {
+        "getVariableData": [
+            {
+                "component": {
+                    "name": "Component",
+                    "evse": {
+                        "id": 1,
+                    },
+                },
+                "variable": {
+                    "name": "Variable",
+                },
+            }
+        ]
+    }