Add JSON loader (#296)

pardata/_high_level.py

@@ -251,6 +251,7 @@ def load_dataset_from_location(url_or_path: Union[str, typing_.PathLike], *,
             RegexFormatPair(regex=r'.*\.(txt|log)', format='text/plain'),
             RegexFormatPair(regex=r'.*\.(jpg|jpeg)', format='image/jpeg'),
             RegexFormatPair(regex=r'.*\.png', format='image/png'),
+            RegexFormatPair(regex=r'.*\.json', format='json'),
         )
 
         for regex_format_pair in regex_format_pairs:

pardata/loaders/_format_loader_map.py

@@ -29,6 +29,7 @@
 from .image import PillowLoader
 from .text import PlainTextLoader
 from .table import CSVPandasLoader
+from .json import JSONLoader
 
 
 class FormatLoaderMap:
@@ -79,6 +80,7 @@ def __contains__(self, fmt: str) -> bool:
     'image/jpeg': PillowLoader(),
     'image/png': PillowLoader(),
     'audio/wav': WaveLoader(),
+    'json': JSONLoader(),
 })
 
 

pardata/loaders/_json.py

@@ -0,0 +1,45 @@
+#
+# Copyright 2021 IBM Corp. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"JSON file loaders."
+
+
+from typing import cast, Dict, Union, Any
+import json
+
+from .. import typing as typing_
+from ..schema import SchemaDict
+from ._base import Loader
+
+
+class JSONLoader(Loader):
+    """Loads a JSON file to an object representing the data."""
+
+    def load(self, path: Union[typing_.PathLike, Dict[str, str]], options: SchemaDict) -> Any:
+        """
+        :param path: The path to the JSON file.
+        :param options: None for JSON loader.
+        :raises TypeError: ``path`` is not a path-like object.
+        :return: An object representing loaded data. See :meth:`json.load` for details.
+        """
+
+        super().load(path, options)
+
+        # We can remove usage of cast once Dict[str, str] handling is added
+        path = cast(typing_.PathLike, path)
+
+        with open(path) as json_file:
+            return json.load(json_file)

pardata/loaders/json.py

@@ -0,0 +1,22 @@
+#
+# Copyright 2021 IBM Corp. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"JSON loaders."
+
+
+from ._json import JSONLoader
+
+__all__ = ('JSONLoader',)

tests/assets/people.json

@@ -0,0 +1,17 @@
+[
+  {
+    "name": "Alice",
+    "age": 25,
+    "state": "California"
+  },
+  {
+    "name": "Bob",
+    "age": 21,
+    "state": "Florida"
+  },
+  {
+    "name": "Carol",
+    "age": 28,
+    "state": "Texas"
+  }
+]

tests/conftest.py

@@ -409,3 +409,10 @@ def bell_sound(asset_dir) -> Path:
     "Path to the service-bell.wav."
 
     return asset_dir / 'service-bell.wav'
+
+
+@pytest.fixture
+def people_json(asset_dir) -> Path:
+    "Path to people.json"
+
+    return asset_dir / 'people.json'

tests/test_loaders.py

@@ -22,6 +22,7 @@
 from pandas.api.types import is_datetime64_any_dtype, is_float_dtype, is_integer_dtype, is_string_dtype
 from PIL import Image, ImageChops
 import wave
+import json
 
 from pardata.dataset import Dataset
 from pardata.loaders import Loader
@@ -31,6 +32,7 @@
 from pardata.loaders.image import PillowLoader
 from pardata.loaders.text import PlainTextLoader
 from pardata.loaders.table import CSVPandasLoader
+from pardata.loaders.json import JSONLoader
 
 
 class TestBaseLoader:
@@ -339,3 +341,15 @@ def test_csv_pandas_header(self, tmp_path, noaa_jfk_schema):
 
         del noaa_jfk_schema['subdatasets']['jfk_weather_cleaned']['format']['options']['no_header']
         self.test_csv_pandas_loader(tmp_path, noaa_jfk_schema)
+
+
+class TestJSONLoaders:
+    def test_json_loader(self, people_json):
+        "Test the normal functionality of JSONLoader"
+
+        with open(people_json) as local:
+            local_content = json.load(local)
+
+        loaded_content = JSONLoader().load(people_json, {})
+
+        assert local_content == loaded_content