[Python] Schema to JSON (#272)

python/tests/test_schema.py

@@ -0,0 +1,78 @@
+#  Copyright 2023 LanceDB Developers
+#
+#  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.
+
+import pyarrow as pa
+
+import lancedb
+from lancedb.schema import dict_to_schema, schema_to_dict
+
+
+def test_schema_to_dict():
+    schema = pa.schema(
+        [
+            pa.field("id", pa.int64()),
+            pa.field("vector", lancedb.vector(512), nullable=False),
+            pa.field(
+                "struct",
+                pa.struct(
+                    [
+                        pa.field("a", pa.utf8()),
+                        pa.field("b", pa.float32()),
+                    ]
+                ),
+                True,
+            ),
+            pa.field("d", pa.dictionary(pa.int64(), pa.utf8()), False),
+        ],
+        metadata={"key": "value"},
+    )
+
+    json_schema = schema_to_dict(schema)
+    assert json_schema == {
+        "fields": [
+            {"name": "id", "type": {"type": "int64"}, "nullable": True},
+            {
+                "name": "vector",
+                "type": {
+                    "type": "fixed_size_list",
+                    "value_type": {"type": "float32"},
+                    "width": 512,
+                },
+                "nullable": False,
+            },
+            {
+                "name": "struct",
+                "type": {
+                    "type": "struct",
+                    "fields": [
+                        {"name": "a", "type": {"type": "string"}, "nullable": True},
+                        {"name": "b", "type": {"type": "float32"}, "nullable": True},
+                    ],
+                },
+                "nullable": True,
+            },
+            {
+                "name": "d",
+                "type": {
+                    "type": "dictionary",
+                    "index_type": {"type": "int64"},
+                    "value_type": {"type": "string"},
+                },
+                "nullable": False,
+            },
+        ],
+        "metadata": {"key": "value"},
+    }
+
+    actual_schema = dict_to_schema(json_schema)
+    assert actual_schema == schema