Cast fields in a view based on type hint for datetime, date, time, timedelta, and uuid.

Author: adamghill

django_unicorn/call_method_parser.py

@@ -1,31 +1,14 @@
 import ast
 import logging
-from datetime import date, datetime, time, timedelta
 from functools import lru_cache
 from types import MappingProxyType
 from typing import Any, Dict, List, Mapping, Tuple
-from uuid import UUID
 
-from django.utils.dateparse import (
-    parse_date,
-    parse_datetime,
-    parse_duration,
-    parse_time,
-)
+from django_unicorn.utils import CASTERS
 
 
 logger = logging.getLogger(__name__)
 
-# Functions that attempt to convert something that failed while being parsed by
-# `ast.literal_eval`.
-CASTERS = {
-    datetime: parse_datetime,
-    time: parse_time,
-    date: parse_date,
-    timedelta: parse_duration,
-    UUID: UUID,
-}
-
 
 class InvalidKwarg(Exception):
     pass

django_unicorn/utils.py

@@ -2,14 +2,22 @@
 import hmac
 import logging
 import pickle
+from datetime import date, datetime, time, timedelta
 from inspect import signature
 from pprint import pprint
 from typing import Dict, List, Union
 from typing import get_type_hints as typing_get_type_hints
+from uuid import UUID
 
 from django.conf import settings
 from django.core.cache import caches
 from django.http import HttpRequest
+from django.utils.dateparse import (
+    parse_date,
+    parse_datetime,
+    parse_duration,
+    parse_time,
+)
 from django.utils.html import _json_script_escapes
 from django.utils.safestring import mark_safe
 
@@ -20,6 +28,19 @@
 from django_unicorn.settings import get_cache_alias
 
 
+try:
+    from typing import get_args, get_origin
+except ImportError:
+    # Fallback to dunder methods for older versions of Python
+    def get_args(type_hint):
+        if hasattr(type_hint, "__args__"):
+            return type_hint.__args__
+
+    def get_origin(type_hint):
+        if hasattr(type_hint, "__origin__"):
+            return type_hint.__origin__
+
+
 try:
     from cachetools.lru import LRUCache
 except ImportError:
@@ -32,6 +53,17 @@
 function_signature_cache = LRUCache(maxsize=100)
 
 
+# Functions that attempt to convert something that failed while being parsed by
+# `ast.literal_eval`.
+CASTERS = {
+    datetime: parse_datetime,
+    time: parse_time,
+    date: parse_date,
+    timedelta: parse_duration,
+    UUID: UUID,
+}
+
+
 def generate_checksum(data: Union[str, bytes]) -> str:
     """
     Generates a checksum for the passed-in data.
@@ -241,6 +273,51 @@ def get_type_hints(obj) -> Dict:
         return {}
 
 
+def cast_value(type_hint, value):
+    """
+    Try to cast the value based on the type hint and
+    `django_unicorn.call_method_parser.CASTERS`.
+
+    Additional features:
+    - convert `int`/`float` epoch to `datetime` or `date`
+    - instantiate the `type_hint` class with passed-in value
+    """
+
+    type_hints = []
+
+    if get_origin(type_hint) is Union:
+        for arg in get_args(type_hint):
+            type_hints.append(arg)
+    else:
+        type_hints.append(type_hint)
+
+    for type_hint in type_hints:
+        caster = CASTERS.get(type_hint)
+
+        if caster:
+            try:
+                value = caster(value)
+                break
+            except TypeError:
+                if (type_hint is datetime or type_hint is date) and (
+                    isinstance(value, int) or isinstance(value, float)
+                ):
+                    try:
+                        value = datetime.fromtimestamp(value)
+
+                        if type_hint is date:
+                            value = value.date()
+
+                        break
+                    except ValueError:
+                        pass
+        else:
+            value = type_hint(value)
+            break
+
+    return value
+
+
 def get_method_arguments(func) -> List[str]:
     """
     Gets the arguments for a method.

django_unicorn/views/action_parsers/call_method.py

@@ -1,29 +1,23 @@
-from datetime import date, datetime
 from typing import Any, Dict, Tuple, Union
 
 from django.db.models import Model
 
 from django_unicorn.call_method_parser import (
-    CASTERS,
     InvalidKwarg,
     parse_call_method_name,
     parse_kwarg,
 )
 from django_unicorn.components import UnicornView
 from django_unicorn.decorators import timed
-from django_unicorn.utils import get_method_arguments, get_type_hints
+from django_unicorn.utils import cast_value, get_method_arguments, get_type_hints
 from django_unicorn.views.action_parsers.utils import set_property_value
 from django_unicorn.views.objects import ComponentRequest, Return
 from django_unicorn.views.utils import set_property_from_data
 
 
 try:
-    from typing import get_args, get_origin
+    from typing import get_origin
 except ImportError:
-    # Fallback to dunder methods for older versions of Python
-    def get_args(type_hint):
-        if hasattr(type_hint, "__args__"):
-            return type_hint.__args__
 
     def get_origin(type_hint):
         if hasattr(type_hint, "__origin__"):
@@ -107,51 +101,6 @@ def handle(component_request: ComponentRequest, component: UnicornView, payload:
     )
 
 
-def _cast_value(type_hint, value):
-    """
-    Try to cast the value based on the type hint and
-    `django_unicorn.call_method_parser.CASTERS`.
-
-    Additional features:
-    - convert `int`/`float` epoch to `datetime` or `date`
-    - instantiate the `type_hint` class with passed-in value
-    """
-
-    type_hints = []
-
-    if get_origin(type_hint) is Union:
-        for arg in get_args(type_hint):
-            type_hints.append(arg)
-    else:
-        type_hints.append(type_hint)
-
-    for type_hint in type_hints:
-        caster = CASTERS.get(type_hint)
-
-        if caster:
-            try:
-                value = caster(value)
-                break
-            except TypeError:
-                if (type_hint is datetime or type_hint is date) and (
-                    isinstance(value, int) or isinstance(value, float)
-                ):
-                    try:
-                        value = datetime.fromtimestamp(value)
-
-                        if type_hint is date:
-                            value = value.date()
-
-                        break
-                    except ValueError:
-                        pass
-        else:
-            value = type_hint(value)
-            break
-
-    return value
-
-
 @timed
 def _call_method_name(
     component: UnicornView, method_name: str, args: Tuple[Any], kwargs: Dict[str, Any]
@@ -207,9 +156,9 @@ def _call_method_name(
                         parsed_kwargs[argument] = DbModel.objects.get(**{key: value})
 
                 elif argument in kwargs:
-                    parsed_kwargs[argument] = _cast_value(type_hint, kwargs[argument])
+                    parsed_kwargs[argument] = cast_value(type_hint, kwargs[argument])
                 else:
-                    parsed_args.append(_cast_value(type_hint, args[len(parsed_args)]))
+                    parsed_args.append(cast_value(type_hint, args[len(parsed_args)]))
             elif argument in kwargs:
                 parsed_kwargs[argument] = kwargs[argument]
             else:

django_unicorn/views/utils.py

@@ -8,6 +8,7 @@
 from django_unicorn.components.typing import QuerySetType
 from django_unicorn.decorators import timed
 from django_unicorn.utils import get_type_hints
+from django_unicorn.views.action_parsers.call_method import cast_value
 
 
 try:
@@ -73,12 +74,8 @@ def set_property_from_data(
             if is_dataclass(type_hint):
                 value = type_hint(**value)
             else:
-                # Construct the specified type by passing the value in
-                # Usually the value will be a string (because it is coming from JSON)
-                # and basic types can be constructed by passing in a string,
-                # i.e. int("1") or float("1.1")
                 try:
-                    value = type_hint(value)
+                    value = cast_value(type_hint, value)
                 except TypeError:
                     # Ignore this exception because some type-hints can't be instantiated like this (e.g. `List[]`)
                     pass
@@ -208,7 +205,7 @@ class TestComponent(UnicornView):
             # Explicitly set `_result_cache` to an empty list
             queryset._result_cache = []
 
-        for (idx, model) in enumerate(queryset._result_cache):
+        for idx, model in enumerate(queryset._result_cache):
             if hasattr(model, "pk") and model.pk == model_value.get("pk"):
                 constructed_model = _construct_model(model_type, model_value)
                 queryset._result_cache[idx] = constructed_model

example/unicorn/components/test_datetime.py

@@ -1,7 +1,10 @@
 from datetime import datetime
+
 from django.utils import timezone
+
 from django_unicorn.components import UnicornView
 
+
 class TestDatetimeView(UnicornView):
     dt: datetime = None
 

example/unicorn/templates/unicorn/test-datetime.html

@@ -1,7 +1,7 @@
 {% load unicorn %}
 <div>
-    <div style="width:200px;height:200px;margin:10px;background-color:#aaffaa" unicorn:click="foo()">
-        {{ dt }}<br>
-        (click me)
-    </div>
+  <div style="width:200px;height:200px;margin:10px;background-color:#aaffaa" unicorn:click="foo()">
+    {{ dt }}<br>
+    (click me)
+  </div>
 </div>

tests/call_method_parser/test_parse_args.py

@@ -1,8 +1,6 @@
 from datetime import datetime
 from uuid import UUID
 
-import pytest
-
 from django_unicorn.call_method_parser import eval_value
 
 

tests/views/utils/test_set_property_from_data.py

@@ -13,7 +13,8 @@
 class FakeComponent(UnicornView):
     string = "property_view"
     integer = 99
-    datetime = datetime(2020, 1, 1)
+    datetime_without_typehint = datetime(2020, 1, 1)
+    datetime_with_typehint: datetime = datetime(2020, 2, 1)
     array: List[str] = []
     model = Flavor(name="test-initial")
     queryset = Flavor.objects.none()
@@ -69,11 +70,22 @@ def test_set_property_from_data_int():
 
 def test_set_property_from_data_datetime():
     component = FakeComponent(component_name="test", component_id="12345678")
-    assert datetime(2020, 1, 1) == component.datetime
+    assert datetime(2020, 1, 1) == component.datetime_without_typehint
 
-    set_property_from_data(component, "datetime", datetime(2020, 1, 2))
+    set_property_from_data(component, "datetime_without_typehint", datetime(2020, 1, 2))
 
-    assert datetime(2020, 1, 2) == component.datetime
+    assert datetime(2020, 1, 2) == component.datetime_without_typehint
+
+
+def test_set_property_from_data_datetime_with_typehint():
+    component = FakeComponent(component_name="test", component_id="12345678")
+    assert datetime(2020, 2, 1) == component.datetime_with_typehint
+
+    set_property_from_data(
+        component, "datetime_with_typehint", str(datetime(2020, 2, 2))
+    )
+
+    assert datetime(2020, 2, 2) == component.datetime_with_typehint
 
 
 def test_set_property_from_data_list():