feat(catalog): add limit parameter to search function and implement describe_catalog

- Add optional `limit` parameter to the `search` function in catalog.py
- Implement new `describe_catalog` function to get column information of a catalog
- Update unit tests to include the new parameter and test the new function
- Minor formatting improvements in docstrings and test cases

csst_dfs_client/catalog.py

@@ -76,3 +76,23 @@ def all_catalog_names() -> Result:
         return Result.ok_data(data = records)
     except Exception as e:
         return Result.error(str(e))
+
+def describe_catalog(catalog_name: str) -> Result:
+    """
+    获取星表各列信息。
+
+    Returns:
+        Result: 列描述的列表。
+
+    Raises:
+        Exception: 如果请求失败，将抛出异常。
+
+    """
+    try:
+        datas = request.get(f'/api/catalog/describe/{catalog_name}')
+        if datas and isinstance(datas, Result):
+            return datas
+        records = pickle.loads(datas._content)
+        return Result.ok_data(data = records)
+    except Exception as e:
+        return Result.error(str(e))

tests/test_catalog.py

@@ -28,3 +28,9 @@ class CatalogTestCase(unittest.TestCase):
         print(result)
         self.assertEqual(result.code, 200, "error code: " + str(result.code) + ", message: " + result.message)
         self.assertIsNotNone(result.data, "error message: " + result.message)
+
+    def test_describe_catalog(self):
+        result = catalog.describe_catalog('gaia3_source')
+        print(result)
+        self.assertEqual(result.code, 200, "error code: " + str(result.code) + ", message: " + result.message)
+        self.assertIsNotNone(result.data, "error message: " + result.message)