Merge pull request #22 from jg-rp/value-setter

Add `parent` and `value` setter to `JSONPathNode`

Author: jg-rp

.github/workflows/tests.yaml

@@ -9,7 +9,24 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+        exclude:
+          - os: macos-latest
+            python-version: "3.8"
+          - os: windows-latest
+            python-version: "3.8"
+          - os: macos-latest
+            python-version: "3.9"
+          - os: windows-latest
+            python-version: "3.9"
+          - os: macos-latest
+            python-version: "3.10"
+          - os: windows-latest
+            python-version: "3.10"
+          - os: macos-latest
+            python-version: "3.11"
+          - os: windows-latest
+            python-version: "3.11"
     steps:
       - uses: actions/checkout@v4
         with:

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Python JSONPath RFC 9535 Change Log
 
+## Version 0.2.0 (unreleased)
+
+**Features**
+
+- Added `JSONPathNode.parent`, a reference the the node's parent node. See [#21](https://github.com/jg-rp/python-jsonpath-rfc9535/issues/21).
+- Changed `JSONPathNode.value` to be a `@property` and `setter`. When assigning to `JSONPathNode.value`, source data is updated too. See [#21](https://github.com/jg-rp/python-jsonpath-rfc9535/issues/21).
+
 ## Version 0.1.6
 
 - Added py.typed.

README.md

@@ -116,16 +116,16 @@ Apply JSONPath expression _query_ to _value_. _value_ should arbitrary, possible
 
 A list of `JSONPathNode` instances is returned, one node for each value matched by _query_. The returned list will be empty if there were no matches.
 
-Each `JSONPathNode` has:
+Each `JSONPathNode` has properties:
 
-- a `value` property, which is the JSON-like value associated with the node.
-- a `location` property, which is a tuple of property names and array/list indexes that were required to reach the node's value in the target JSON document.
-- a `path()` method, which returns the normalized path to the node in the target JSON document.
+- `value` - The JSON-like value associated with the node.
+- `location` - A tuple of property names and array/list indexes that were required to reach the node's value in the target JSON document.
+- `parent` (_New in version 0.2.0_) - The node's parent node, or `None` if the current node is the root.
 
 ```python
 import jsonpath_rfc9535 as jsonpath
 
-value = {
+data = {
     "users": [
         {"name": "Sue", "score": 100},
         {"name": "John", "score": 86, "admin": True},
@@ -135,18 +135,36 @@ value = {
     "moderator": "John",
 }
 
-for node in jsonpath.find("$.users[?@.score > 85]", value):
+nodes = jsonpath.find("$.users[?@.score > 85]", data)
+
+for node in nodes:
     print(f"{node.value} at '{node.path()}'")
 
 # {'name': 'Sue', 'score': 100} at '$['users'][0]'
 # {'name': 'John', 'score': 86, 'admin': True} at '$['users'][1]'
 ```
 
+`JSONPathNode.path()` returns the normalized path to the node in the target JSON document.
+
 `JSONPathNodeList` is a subclass of `list` with some helper methods.
 
 - `values()` returns a list of values, one for each node.
 - `items()` returns a list of `(normalized path, value)` tuples.
 
+**_New in version 0.2.0_**
+
+Assigning to `JSONPathNode.value` will update the node's value **and mutate source data**. Beware,updating data after evaluating a query can invalidate existing child node paths.
+
+```python
+# ... continued from above
+
+node = jsonpath.find_one("$.users[@.name == 'John'].score")
+if node:
+    node.value = 999
+
+print(data["users"][1])  # {'name': 'John', 'score': 999, 'admin': True}
+```
+
 ### find_one
 
 `find_one(query: str, value: JSONValue) -> Optional[JSONPathNode]`

jsonpath_rfc9535/__about__.py

@@ -1 +1 @@
-__version__ = "0.1.6"
+__version__ = "0.2.0"

jsonpath_rfc9535/node.py

@@ -4,6 +4,7 @@
 
 from typing import TYPE_CHECKING
 from typing import List
+from typing import Optional
 from typing import Tuple
 from typing import Union
 
@@ -16,14 +17,20 @@
 class JSONPathNode:
     """A JSON-like value and its location in a JSON document.
 
+    Assigning to `JSONPathNode.value` will update and mutate source data too.
+    Updating data after evaluating a query can invalidate existing child
+    nodes. Use at your own risk.
+
     Attributes:
         value: The JSON-like value at this node.
         location: The names indices that make up the normalized path to _value_.
+        parent: The parent node, or None if this is the root node.
     """
 
     __slots__ = (
-        "value",
+        "_value",
         "location",
+        "parent",
         "root",
     )
 
@@ -32,24 +39,46 @@ def __init__(
         *,
         value: object,
         location: Tuple[Union[int, str], ...],
+        parent: Optional[JSONPathNode],
         root: JSONValue,
     ) -> None:
-        self.value: object = value
+        self._value: object = value
         self.location: Tuple[Union[int, str], ...] = location
+        self.parent = parent
         self.root = root
 
+    @property
+    def value(self) -> object:
+        """The JSON-like value at this node."""
+        return self._value
+
+    @value.setter
+    def value(self, val: object) -> None:
+        parent = self.parent
+        if parent is not None and self.location:
+            # If data has changed since this node was created, this could fail.
+            # Letting the exception raise is probably the most useful thing we can do.
+            parent._value[self.location[-1]] = val  # type: ignore  # noqa: SLF001
+        self._value = val
+
     def path(self) -> str:
         """Return the normalized path to this node."""
         return "$" + "".join(
             f"[{canonical_string(p)}]" if isinstance(p, str) else f"[{p}]"
             for p in self.location
         )
 
-    def new_child(self, value: object, key: Union[int, str]) -> JSONPathNode:
+    def new_child(
+        self,
+        value: object,
+        key: Union[int, str],
+        parent: Optional[JSONPathNode],
+    ) -> JSONPathNode:
         """Return a new node using this node's location."""
         return JSONPathNode(
             value=value,
             location=self.location + (key,),
+            parent=parent,
             root=self.root,
         )
 

jsonpath_rfc9535/query.py

@@ -70,6 +70,7 @@ def finditer(
             JSONPathNode(
                 value=value,
                 location=(),
+                parent=None,
                 root=value,
             )
         ]

jsonpath_rfc9535/segments.py

@@ -88,12 +88,12 @@ def _visit(self, node: JSONPathNode, depth: int = 1) -> Iterable[JSONPathNode]:
         if isinstance(node.value, dict):
             for name, val in node.value.items():
                 if isinstance(val, (dict, list)):
-                    _node = node.new_child(val, name)
+                    _node = node.new_child(val, name, node)
                     yield from self._visit(_node, depth + 1)
         elif isinstance(node.value, list):
             for i, element in enumerate(node.value):
                 if isinstance(element, (dict, list)):
-                    _node = node.new_child(element, i)
+                    _node = node.new_child(element, i, node)
                     yield from self._visit(_node, depth + 1)
 
     def _nondeterministic_visit(
@@ -167,7 +167,7 @@ def _nondeterministic_children(node: JSONPathNode) -> Iterable[JSONPathNode]:
         items = list(node.value.items())
         random.shuffle(items)
         for name, val in items:
-            yield node.new_child(val, name)
+            yield node.new_child(val, name, node)
     elif isinstance(node.value, list):
         for i, element in enumerate(node.value):
-            yield node.new_child(element, i)
+            yield node.new_child(element, i, node)

jsonpath_rfc9535/selectors.py

@@ -77,7 +77,7 @@ def resolve(self, node: JSONPathNode) -> Iterable[JSONPathNode]:
         """Select a value from a dict/object by its property/key."""
         if isinstance(node.value, dict):
             with suppress(KeyError):
-                yield node.new_child(node.value[self.name], self.name)
+                yield node.new_child(node.value[self.name], self.name, node)
 
 
 class IndexSelector(JSONPathSelector):
@@ -122,7 +122,7 @@ def resolve(self, node: JSONPathNode) -> Iterable[JSONPathNode]:
         if isinstance(node.value, list):
             norm_index = self._normalized_index(node.value)
             with suppress(IndexError):
-                yield node.new_child(node.value[self.index], norm_index)
+                yield node.new_child(node.value[self.index], norm_index, node)
 
 
 class SliceSelector(JSONPathSelector):
@@ -172,7 +172,7 @@ def resolve(self, node: JSONPathNode) -> Iterable[JSONPathNode]:
             for idx, element in zip(  # noqa: B905
                 range(*self.slice.indices(len(node.value))), node.value[self.slice]
             ):
-                yield node.new_child(element, idx)
+                yield node.new_child(element, idx, node)
 
 
 class WildcardSelector(JSONPathSelector):
@@ -201,11 +201,11 @@ def resolve(self, node: JSONPathNode) -> Iterable[JSONPathNode]:
                 members = node.value.items()
 
             for name, val in members:
-                yield node.new_child(val, name)
+                yield node.new_child(val, name, node)
 
         elif isinstance(node.value, list):
             for i, element in enumerate(node.value):
-                yield node.new_child(element, i)
+                yield node.new_child(element, i, node)
 
 
 class FilterSelector(JSONPathSelector):
@@ -254,7 +254,7 @@ def resolve(self, node: JSONPathNode) -> Iterable[JSONPathNode]:  # noqa: PLR091
                 )
                 try:
                     if self.expression.evaluate(context):
-                        yield node.new_child(val, name)
+                        yield node.new_child(val, name, node)
                 except JSONPathTypeError as err:
                     if not err.token:
                         err.token = self.token
@@ -269,7 +269,7 @@ def resolve(self, node: JSONPathNode) -> Iterable[JSONPathNode]:  # noqa: PLR091
                 )
                 try:
                     if self.expression.evaluate(context):
-                        yield node.new_child(element, i)
+                        yield node.new_child(element, i, node)
                 except JSONPathTypeError as err:
                     if not err.token:
                         err.token = self.token

tests/cts

@@ -4,3 +4,23 @@
 def test_issue_13() -> None:
     # This was failing with "unbalanced parentheses".
     _q = jsonpath.compile("$[? count(@.likes[? @.location]) > 3]")
+
+
+def test_issue_21() -> None:
+    data = {"foo": {"bar": {"baz": 42}}}
+    node = jsonpath.find_one("$.foo.bar.baz", data)
+
+    expected = 42
+    assert node is not None
+    assert node.value == expected
+    assert data["foo"]["bar"]["baz"] == expected
+
+    new_value = 99
+    node.value = new_value
+    assert node.value == new_value
+    assert data["foo"]["bar"]["baz"] == new_value
+
+    parent = node.parent
+    assert parent is not None
+    assert parent.value == {"baz": new_value}
+    assert parent.value["baz"] == new_value  # type: ignore