fix: pointers without slashes, closes #27

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Version 0.9.0 (unreleased)
 
+**Fixes**
+
+- Fixed a bug with the parsing of JSON Pointers. When given an arbitrary string without slashes, `JSONPointer` would resolve to the document root. The empty string is the only valid pointer that should resolve to the document root. See [#27](https://github.com/jg-rp/python-jsonpath/issues/27).
+
 **Features**
 
 - Added a command line interface, exposing JSONPath, JSON Pointer and JSON Patch features.

jsonpath/cli.py

@@ -9,7 +9,7 @@
 from jsonpath.exceptions import JSONPathIndexError
 from jsonpath.exceptions import JSONPathSyntaxError
 from jsonpath.exceptions import JSONPathTypeError
-from jsonpath.exceptions import JSONPointerResolutionError
+from jsonpath.exceptions import JSONPointerError
 
 INDENT = 2
 
@@ -295,7 +295,7 @@ def handle_pointer_command(args: argparse.Namespace) -> None:
  raise
  sys.stderr.write(f"target document json decode error: {err}\n")
  sys.exit(1)
- except JSONPointerResolutionError as err:
+ except JSONPointerError as err:
  if args.debug:
  raise
  sys.stderr.write(str(err) + "\n")

jsonpath/patch.py

@@ -382,9 +382,12 @@ def _op_pointer(
  f"({op}:{i})"
  )
 
- return JSONPointer(
- pointer, unicode_escape=self.unicode_escape, uri_decode=self.uri_decode
- )
+ try:
+ return JSONPointer(
+ pointer, unicode_escape=self.unicode_escape, uri_decode=self.uri_decode
+ )
+ except JSONPointerError as err:
+ raise JSONPatchError(f"{err} ({op}:{i})") from err
 
  def _op_value(
  self, operation: Mapping[str, object], key: str, op: str, i: int

jsonpath/pointer.py

@@ -15,6 +15,7 @@
 from typing import Union
 from urllib.parse import unquote
 
+from .exceptions import JSONPointerError
 from .exceptions import JSONPointerIndexError
 from .exceptions import JSONPointerKeyError
 from .exceptions import JSONPointerResolutionError
@@ -93,8 +94,12 @@ def _parse(
  .decode("utf-16")
  )
 
- # TODO: lstrip pointer
- # TODO: handle pointer without leading slash and not empty string
+ s = s.lstrip()
+ if s and not s.startswith("/"):
+ raise JSONPointerError(
+ "pointer must start with a slash or be the empty string"
+ )
+
  return tuple(
  self._index(p.replace("~1", "/").replace("~0", "~")) for p in s.split("/")
  )[1:]

tests/test_json_pointer.py

@@ -7,6 +7,7 @@
 
 import jsonpath
 from jsonpath import JSONPointer
+from jsonpath import JSONPointerError
 from jsonpath import JSONPointerIndexError
 from jsonpath import JSONPointerResolutionError
 from jsonpath import JSONPointerTypeError
@@ -117,9 +118,9 @@ def test_resolve_with_missing_parent() -> None:
 
 def test_resolve_with_missing_target() -> None:
  data = {"some": {"thing": [1, 2, 3]}}
- pointer = JSONPointer("some/other")
+ pointer = JSONPointer("/some/other")
  parent, rv = pointer.resolve_parent(data)
- assert parent == data
+ assert parent == data["some"]
  assert rv == UNDEFINED
 
 
@@ -204,3 +205,17 @@ def test_index_with_leading_zero() -> None:
  pointer = JSONPointer("/some/thing/01")
  with pytest.raises(JSONPointerTypeError):
  pointer.resolve_parent(data)
+
+
+def test_pointer_without_leading_slash() -> None:
+ with pytest.raises(JSONPointerError):
+ JSONPointer("some/thing/01")
+
+ with pytest.raises(JSONPointerError):
+ JSONPointer("nosuchthing")
+
+
+def test_pointer_with_leading_whitespace() -> None:
+ data = {"some": {"thing": [1, 2, 3]}}
+ pointer = JSONPointer(" /some/thing/0")
+ assert pointer.resolve(data) == 1