Smarter redirect on slice creation (#691)

After ea8a7ec1ba creating a slice
started redirecting to druid datasource from sqlalchemy tables.
That's quite painful for sqlalchemy tables users.
Instead of hardcoding a choice just query the db, if we don't
have any druid datasource fallback to sqlalchemy tables.
Bonus points we remove hacky javascript and make the message
translatable.

While at it fix druid client test to not hardcode datasource id.

caravel/templates/caravel/add_slice.html

@@ -1,6 +0,0 @@
-<script>
-  var msg = "Click on a datasource link to create a Slice, " +
-          "or click on a table link <a href='/tablemodelview/list/'>here</a> " +
-          "to create a Slice for a table";
-  window.location = "/r/msg/?url={{ '/druiddatasourcemodelview/list/' }}&msg=" + msg;
-</script>

caravel/views.py

@@ -520,7 +520,6 @@ if config['DRUID_IS_ACTIVE']:
 
 class SliceModelView(CaravelModelView, DeleteMixin):  # noqa
     datamodel = SQLAInterface(models.Slice)
-    add_template = "caravel/add_slice.html"
     can_add = False
     label_columns = {
         'datasource_link': 'Datasource',
@@ -568,6 +567,28 @@ class SliceModelView(CaravelModelView, DeleteMixin):  # noqa
     def pre_delete(self, obj):
         check_ownership(obj)
 
+    @expose('/add', methods=['GET', 'POST'])
+    @has_access
+    def add(self):
+        widget = self._add()
+        if not widget:
+            return redirect(self.get_redirect())
+
+        a_druid_datasource = db.session.query(models.DruidDatasource).first()
+        if a_druid_datasource is not None:
+            url = "/druiddatasourcemodelview/list/"
+            msg = _(
+                "Click on a datasource link to create a Slice, "
+                "or click on a table link <a href='/tablemodelview/list/'>here</a> "
+                "to create a Slice for a table"
+            )
+        else:
+            url = "/tablemodelview/list/"
+            msg = _("Click on a table link to create a Slice")
+
+        redirect_url = "/r/msg/?url={}&msg={}".format(url, msg)
+        return redirect(redirect_url)
+
 appbuilder.add_view(
     SliceModelView,
     "Slices",

tests/core_tests.py

@@ -17,7 +17,7 @@ from flask_appbuilder.security.sqla import models as ab_models
 
 import caravel
 from caravel import app, db, models, utils, appbuilder
-from caravel.models import DruidCluster
+from caravel.models import DruidCluster, DruidDatasource
 
 os.environ['CARAVEL_CONFIG'] = 'tests.caravel_test_config'
 
@@ -218,6 +218,27 @@ class CoreTests(CaravelTestCase):
         assert new_slice in dash.slices
         assert len(set(dash.slices)) == len(dash.slices)
 
+    def test_add_slice_redirect_to_sqla(self, username='admin'):
+        self.login(username=username)
+        url = '/slicemodelview/add'
+        resp = self.client.get(url, follow_redirects=True)
+        assert "Click on a table link to create a Slice" in resp.data.decode('utf-8')
+
+    def test_add_slice_redirect_to_druid(self, username='admin'):
+        datasource = DruidDatasource(
+            datasource_name="datasource_name",
+        )
+        db.session.add(datasource)
+        db.session.commit()
+
+        self.login(username=username)
+        url = '/slicemodelview/add'
+        resp = self.client.get(url, follow_redirects=True)
+        assert "Click on a datasource link to create a Slice" in resp.data.decode('utf-8')
+
+        db.session.delete(datasource)
+        db.session.commit()
+
     def test_gamma(self):
         self.login(username='gamma')
         resp = self.client.get('/slicemodelview/list/')
@@ -409,7 +430,7 @@ class DruidTests(CaravelTestCase):
         instance.export_pandas.return_value = df
         instance.query_dict = {}
         instance.query_builder.last_query.query_dict = {}
-        resp = self.client.get('/caravel/explore/druid/1/?viz_type=table&granularity=one+day&druid_time_origin=&since=7+days+ago&until=now&row_limit=5000&include_search=false&metrics=count&groupby=name&flt_col_0=dim1&flt_op_0=in&flt_eq_0=&slice_id=&slice_name=&collapsed_fieldsets=&action=&datasource_name=test_datasource&datasource_id=1&datasource_type=druid&previous_viz_type=table&json=true&force=true')
+        resp = self.client.get('/caravel/explore/druid/{}/?viz_type=table&granularity=one+day&druid_time_origin=&since=7+days+ago&until=now&row_limit=5000&include_search=false&metrics=count&groupby=name&flt_col_0=dim1&flt_op_0=in&flt_eq_0=&slice_id=&slice_name=&collapsed_fieldsets=&action=&datasource_name=test_datasource&datasource_id={}&datasource_type=druid&previous_viz_type=table&json=true&force=true'.format(datasource_id, datasource_id))
         assert "Canada" in resp.data.decode('utf-8')