feat: add database dropdown to dashboard import (#10118)

* feat: add database dropdown to dashboard import

Currently, when importing a database from a JSON file, the process
looks at the database name from the source (the info is in the file)
and matches the datasources to that name. If no database by that name
exists, it simply fails.

With this PR, we add a database dropdown that allows the user to specify
which databases the datasources should target as the get upserted.

I want to stress that the code in this area is not in a great shape,
and that the challenge of serializing/deser the nested objects is
challenging, but that there should be a much better way to do this.
One of the improvement (out of scope for this PR) that would allow to
simplify those import/export would be to use UUIDs for
importable/exportable objects.

Another identified issue is the indirections between
`utils/import_expor_{model}.py` on top of `{Model}.import_object`. Not
addressing that here.

Next topic is the MVC stuff. Decided to stick with it for now as this is
more of a [obious missing feat:] than a rewrite.

* isort \!? 0%^$%Y$&?%$^?%0^?

* fix tests

* pre-committing to py3.6

* address dpgaspar's comments

* revert isort

superset/utils/dashboard_import_export.py

@@ -21,9 +21,11 @@ from datetime import datetime
 from io import BytesIO
 from typing import Any, Dict, Optional
 
+from flask_babel import lazy_gettext as _
 from sqlalchemy.orm import Session
 
 from superset.connectors.sqla.models import SqlaTable, SqlMetric, TableColumn
+from superset.exceptions import DashboardImportException
 from superset.models.dashboard import Dashboard
 from superset.models.slice import Slice
 
@@ -69,14 +71,19 @@ def decode_dashboards(  # pylint: disable=too-many-return-statements
 
 
 def import_dashboards(
-    session: Session, data_stream: BytesIO, import_time: Optional[int] = None
+    session: Session,
+    data_stream: BytesIO,
+    database_id: Optional[int] = None,
+    import_time: Optional[int] = None,
 ) -> None:
     """Imports dashboards from a stream to databases"""
     current_tt = int(time.time())
     import_time = current_tt if import_time is None else import_time
     data = json.loads(data_stream.read(), object_hook=decode_dashboards)
+    if not data:
+        raise DashboardImportException(_("No data in file"))
     for table in data["datasources"]:
-        type(table).import_obj(table, import_time=import_time)
+        type(table).import_obj(table, database_id, import_time=import_time)
     session.commit()
     for dashboard in data["dashboards"]:
         Dashboard.import_obj(dashboard, import_time=import_time)

superset/utils/import_datasource.py

@@ -24,12 +24,13 @@ from sqlalchemy.orm.session import make_transient
 logger = logging.getLogger(__name__)
 
 
-def import_datasource(
+def import_datasource(  # pylint: disable=too-many-arguments
     session: Session,
     i_datasource: Model,
     lookup_database: Callable[[Model], Model],
     lookup_datasource: Callable[[Model], Model],
     import_time: Optional[int] = None,
+    database_id: Optional[int] = None,
 ) -> int:
     """Imports the datasource from the object to the database.
 
@@ -41,7 +42,9 @@ def import_datasource(
     logger.info("Started import of the datasource: %s", i_datasource.to_json())
 
     i_datasource.id = None
-    i_datasource.database_id = lookup_database(i_datasource).id
+    i_datasource.database_id = (
+        database_id if database_id else lookup_database(i_datasource).id
+    )
     i_datasource.alter_params(import_time=import_time)
 
     # override the datasource

superset/utils/log.py

@@ -24,6 +24,7 @@ from datetime import datetime
 from typing import Any, Callable, cast, Optional, Type
 
 from flask import current_app, g, request
+from sqlalchemy.exc import SQLAlchemyError
 
 from superset.stats_logger import BaseStatsLogger
 
@@ -169,6 +170,10 @@ class DBEventLogger(AbstractEventLogger):
             )
             logs.append(log)
 
-        sesh = current_app.appbuilder.get_session
-        sesh.bulk_save_objects(logs)
-        sesh.commit()
+        try:
+            sesh = current_app.appbuilder.get_session
+            sesh.bulk_save_objects(logs)
+            sesh.commit()
+        except SQLAlchemyError as ex:
+            logging.error("DBEventLogger failed to log event(s)")
+            logging.exception(ex)