Druid dashboard import/export. (#1930)

* Druid dashboard import

* Fix tests.

* Parse params with trailing commas

* Resolved issue with datasource is not in DB yet when slice perms are set

* Finish rebase

* Fix heads alembic problem.

superset/import_util.py

@@ -0,0 +1,74 @@
+import logging
+from sqlalchemy.orm.session import make_transient
+
+
+def import_datasource(
+        session,
+        i_datasource,
+        lookup_database,
+        lookup_datasource,
+        import_time):
+    """Imports the datasource from the object to the database.
+
+     Metrics and columns and datasource will be overrided if exists.
+     This function can be used to import/export dashboards between multiple
+     superset instances. Audit metadata isn't copies over.
+    """
+    make_transient(i_datasource)
+    logging.info('Started import of the datasource: {}'.format(
+        i_datasource.to_json()))
+
+    i_datasource.id = None
+    i_datasource.database_id = lookup_database(i_datasource).id
+    i_datasource.alter_params(import_time=import_time)
+
+    # override the datasource
+    datasource = lookup_datasource(i_datasource)
+
+    if datasource:
+        datasource.override(i_datasource)
+        session.flush()
+    else:
+        datasource = i_datasource.copy()
+        session.add(datasource)
+        session.flush()
+
+    for m in i_datasource.metrics:
+        new_m = m.copy()
+        new_m.table_id = datasource.id
+        logging.info('Importing metric {} from the datasource: {}'.format(
+            new_m.to_json(), i_datasource.full_name))
+        imported_m = i_datasource.metric_cls.import_obj(new_m)
+        if (imported_m.metric_name not in
+                [m.metric_name for m in datasource.metrics]):
+            datasource.metrics.append(imported_m)
+
+    for c in i_datasource.columns:
+        new_c = c.copy()
+        new_c.table_id = datasource.id
+        logging.info('Importing column {} from the datasource: {}'.format(
+            new_c.to_json(), i_datasource.full_name))
+        imported_c = i_datasource.column_cls.import_obj(new_c)
+        if (imported_c.column_name not in
+                [c.column_name for c in datasource.columns]):
+            datasource.columns.append(imported_c)
+    session.flush()
+    return datasource.id
+
+
+def import_simple_obj(session, i_obj, lookup_obj):
+    make_transient(i_obj)
+    i_obj.id = None
+    i_obj.table = None
+
+    # find if the column was already imported
+    existing_column = lookup_obj(i_obj)
+    i_obj.table = None
+    if existing_column:
+        existing_column.override(i_obj)
+        session.flush()
+        return existing_column
+
+    session.add(i_obj)
+    session.flush()
+    return i_obj

superset/migrations/versions/1296d28ec131_druid_exports.py

@@ -0,0 +1,22 @@
+"""Adds params to the datasource (druid) table
+
+Revision ID: 1296d28ec131
+Revises: e46f2d27a08e
+Create Date: 2016-12-06 17:40:40.389652
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '1296d28ec131'
+down_revision = '1b2c3f7c96f9'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column('datasources', sa.Column('params', sa.String(length=1000), nullable=True))
+
+
+def downgrade():
+    op.drop_column('datasources', 'params')