Add support for DatumInContext inplace updating

Author: mokeyish

jsonpath_ng/jsonpath.py

@@ -102,10 +102,20 @@ def wrap(cls, data):
             return cls(data)
 
     def __init__(self, value, path: Optional[JSONPath]=None, context: Optional[DatumInContext]=None):
-        self.value = value
+        self.__value__ = value
         self.path = path or This()
         self.context = None if context is None else DatumInContext.wrap(context)
 
+    @property
+    def value(self):
+        return self.__value__
+
+    @value.setter
+    def value(self, value):
+        if self.context is not None and self.context.value is not None:
+            self.path.update(self.context.value, value)
+        self.__value__ = value
+
     def in_context(self, context, path):
         context = DatumInContext.wrap(context)
 
@@ -694,7 +704,7 @@ def _find_base(self, datum, create):
         for index in self.indices:
             # invalid indices do not crash, return [] instead
             if datum.value and len(datum.value) > index:
-                rv += [DatumInContext(datum.value[index], path=self, context=datum)]
+                rv += [DatumInContext(datum.value[index], path=Index(index), context=datum)]
         return rv
 
     def update(self, data, val):

tests/test_jsonpath.py

@@ -1,11 +1,12 @@
 import copy
 
 import pytest
-
+from typing import Callable
 from jsonpath_ng.ext.parser import parse as ext_parse
 from jsonpath_ng.jsonpath import DatumInContext, Fields, Root, This
 from jsonpath_ng.lexer import JsonPathLexerError
 from jsonpath_ng.parser import parse as base_parse
+from jsonpath_ng import JSONPath
 
 from .helpers import assert_full_path_equality, assert_value_equality
 
@@ -166,12 +167,26 @@ def test_datumincontext_in_context_nested():
     update_test_cases,
 )
 @parsers
-def test_update(parse, expression, data, update_value, expected_value):
+def test_update(parse: Callable[[str], JSONPath], expression: str, data, update_value, expected_value):
     data_copy = copy.deepcopy(data)
     update_value_copy = copy.deepcopy(update_value)
     result = parse(expression).update(data_copy, update_value_copy)
     assert result == expected_value
 
+    # inplace update testing
+    data_copy2 = copy.deepcopy(data)
+    update_value_copy2 = copy.deepcopy(update_value)
+    datums = parse(expression).find(data_copy2)
+    batch_update = isinstance(update_value, list) and len(datums) == len(update_value)
+    for i, datum in enumerate(datums):
+        if batch_update:
+            datum.value = update_value_copy2[i]
+        else:
+            datum.value = update_value_copy2
+        if isinstance(datum.full_path, (Root, This)): # when the type of `data` is str, int, float etc.
+            data_copy2 = datum.value
+    assert data_copy2 == expected_value
+
 
 find_test_cases = (
     #