Merge pull request #64 from jg-rp/compiled-select

Allow `Query.select()` to accept precompiled paths

docs/query.md

@@ -166,12 +166,16 @@ for product in query("$..products.*", data).values():
 {'title': 'Beanie', 'description': 'Winter running hat.', 'price': 9.0}
 ```
 
-We can select nested values too.
+We can select nested values too, and arguments to `select()` can be pre-compiled paths.
 
 ```python
+import jsonpath
+
 # ...
 
-for product in query("$..products.*", data).select("title", "social.shares"):
+projection = (jsonpath.compile("title"), jsonpath.compile("social.shares"))
+
+for product in jsonpath.query("$..products.*", data).select(*projection):
  print(product)
 ```
 

jsonpath/fluent_api.py

@@ -22,6 +22,8 @@
 from .patch import JSONPatch
 
 if TYPE_CHECKING:
+ from jsonpath import CompoundJSONPath
+ from jsonpath import JSONPath
  from jsonpath import JSONPathEnvironment
  from jsonpath import JSONPathMatch
  from jsonpath import JSONPointer
@@ -191,7 +193,7 @@ def take(self, n: int) -> Query:
 
  def select(
  self,
- *expressions: str,
+ *expressions: Union[str, JSONPath, CompoundJSONPath],
  projection: Projection = Projection.RELATIVE,
  ) -> Iterable[object]:
  """Query projection using relative JSONPaths.
@@ -217,7 +219,7 @@ def select(
  def _select(
  self,
  match: JSONPathMatch,
- expressions: Tuple[str, ...],
+ expressions: Tuple[Union[str, JSONPath, CompoundJSONPath], ...],
  projection: Projection,
  ) -> object:
  if isinstance(match.obj, str):
@@ -232,20 +234,21 @@ def _select(
  patch = JSONPatch()
 
  for expr in expressions:
- self._patch(match, expr, patch, projection)
+ path = self._env.compile(expr) if isinstance(expr, str) else expr
+ self._patch(match, path, patch, projection)
 
  return _fix_sparse_arrays(patch.apply(obj))
 
  def _patch(
  self,
  match: JSONPathMatch,
- expr: str,
+ path: Union[JSONPath, CompoundJSONPath],
  patch: JSONPatch,
  projection: Projection,
  ) -> None:
  root_pointer = match.pointer()
 
- for rel_match in self._env.finditer(expr, match.obj): # type: ignore
+ for rel_match in path.finditer(match.obj): # type: ignore
  if projection == Projection.FLAT:
  patch.addap("/-", rel_match.obj)
  elif projection == Projection.ROOT:

tests/test_query_projection.py

@@ -159,3 +159,11 @@ def test_sparse_array_selection() -> None:
  assert list(it) == [
  {"categories": [{"products": [{"title": "Beanie", "social": {"shares": 7}}]}]}
  ]
+
+
+def test_pre_compiled_select_many() -> None:
+ expr = "$.*"
+ data = [{"a": 1, "b": 1, "c": 1}, {"a": 2, "b": 2, "c": 2}, {"b": 3, "a": 3}]
+ projection = (jsonpath.compile("a"), "c")
+ it = jsonpath.query(expr, data).select(*projection)
+ assert list(it) == [{"a": 1, "c": 1}, {"a": 2, "c": 2}, {"a": 3}]