feat(server): Add file info route

arbalister/adbc.py

@@ -37,19 +37,26 @@ class SqliteDataFrame:
     _offset: int | None = None
     _select: list[str] | None = None
 
-    @classmethod
-    def read_sqlite(cls, context: Any, path: pathlib.Path | str, table_name: str | None = None) -> Self:
-        """Read an Sqlite file metadata and start a new DataFrame plan."""
+    @staticmethod
+    def get_table_names(path: pathlib.Path | str) -> list[str]:
+        """Get the list of table names in a SQLite database."""
         with adbc_sqlite.connect(str(path)) as connection:
             with connection.cursor() as cursor:
                 cursor.execute("SELECT name FROM sqlite_master WHERE type='table'")
-                tables = [row for (row,) in cursor.fetchall()]
+                return [row for (row,) in cursor.fetchall()]
 
-                if table_name is None and len(tables) > 0:
-                    table_name = tables[0]
-                if table_name not in tables or table_name is None:
-                    raise ValueError(f"Invalid table name {table_name}")
+    @classmethod
+    def read_sqlite(cls, context: Any, path: pathlib.Path | str, table_name: str | None = None) -> Self:
+        """Read an Sqlite file metadata and start a new DataFrame plan."""
+        tables = cls.get_table_names(path)
+
+        if table_name is None and len(tables) > 0:
+            table_name = tables[0]
+        if table_name not in tables or table_name is None:
+            raise ValueError(f"Invalid table name {table_name}")
 
+        with adbc_sqlite.connect(str(path)) as connection:
+            with connection.cursor() as cursor:
                 cursor.execute(f'SELECT COUNT(*) FROM "{table_name}"')
                 num_rows = cursor.fetchone()[0]  # type: ignore[index]
 

arbalister/routes.py

@@ -139,6 +139,13 @@ class StatsResponse:
     num_cols: int = 0
 
 
+@dataclasses.dataclass(frozen=True, slots=True)
+class SqliteFileInfo:
+    """File-specific information returned in the file info route."""
+
+    table_names: list[str] | None = None
+
+
 class StatsRouteHandler(BaseRouteHandler):
     """An handler to get file in IPC."""
 
@@ -180,6 +187,28 @@ async def get(self, path: str) -> None:
         await self.finish(dataclasses.asdict(response))
 
 
+class FileInfoRouteHandler(BaseRouteHandler):
+    """A handler to get file-specific information."""
+
+    @tornado.web.authenticated
+    async def get(self, path: str) -> None:
+        """HTTP GET return file-specific information."""
+        file = self.data_file(path)
+        file_format = ff.FileFormat.from_filename(file)
+
+        table_names: list[str] | None = None
+
+        if file_format == ff.FileFormat.Sqlite:
+            from . import adbc
+
+            table_names = adbc.SqliteDataFrame.get_table_names(file)
+
+            response = SqliteFileInfo(table_names=table_names)
+            await self.finish(dataclasses.asdict(response))
+
+        await self.finish({})
+
+
 def make_datafusion_config() -> dn.SessionConfig:
     """Return the datafusion config."""
     config = (
@@ -203,6 +232,7 @@ def setup_route_handlers(web_app: jupyter_server.serverapp.ServerWebApplication)
     handlers = [
         (url_path_join(base_url, r"arrow/stream/([^?]*)"), IpcRouteHandler, {"context": context}),
         (url_path_join(base_url, r"arrow/stats/([^?]*)"), StatsRouteHandler, {"context": context}),
+        (url_path_join(base_url, r"file/info/([^?]*)"), FileInfoRouteHandler, {"context": context}),
     ]
 
     web_app.add_handlers(host_pattern, handlers)  # type: ignore[no-untyped-call]

arbalister/tests/test_routes.py

@@ -227,3 +227,23 @@ async def test_stats_route(
     table = pa.ipc.open_stream(table_64).read_all()
     assert table.num_rows == 0
     assert table.schema.names == full_table.schema.names
+
+
+async def test_file_info_route_sqlite(
+    jp_fetch: JpFetch,
+    table_file: pathlib.Path,
+    file_format: ff.FileFormat,
+) -> None:
+    """Test fetching file info for SQLite files returns table names."""
+    response = await jp_fetch("file/info/", str(table_file))
+
+    assert response.code == 200
+    assert response.headers["Content-Type"] == "application/json; charset=UTF-8"
+
+    payload = json.loads(response.body)
+
+    if file_format == ff.FileFormat.Sqlite:
+        assert payload["table_names"] is not None
+        assert isinstance(payload["table_names"], list)
+        assert "dummy_table_1" in payload["table_names"]
+        assert "dummy_table_2" in payload["table_names"]