fix 2b90b41a556a_create_placeholders by null enviroment

ereuse_devicehub/migrations/versions/2b90b41a556a_create_placeholders.py

@@ -7,6 +7,8 @@ Create Date: 2022-07-19 12:17:16.690865
 """
 import copy
 
+from alembic import context, op
+
 from ereuse_devicehub.config import DevicehubConfig
 from ereuse_devicehub.db import db
 from ereuse_devicehub.devicehub import Devicehub
@@ -36,6 +38,13 @@ branch_labels = None
 depends_on = None
 
 
+def get_inv():
+    INV = context.get_x_argument(as_dictionary=True).get('inventory')
+    if not INV:
+        raise ValueError("Inventory value is not specified")
+    return INV
+
+
 def init_app():
     app = Devicehub(inventory=DevicehubConfig.DB_SCHEMA)
     app.app_context().push()
@@ -207,6 +216,11 @@ def remove_placeholders():
 
 
 def upgrade():
+    con = op.get_bind()
+    devices = con.execute(f'select * from {get_inv()}.device')
+    if not list(devices):
+        return
+
     init_app()
     clone_computers()
     manual_actions()
@@ -214,6 +228,11 @@ def upgrade():
 
 
 def downgrade():
+    con = op.get_bind()
+    devices = con.execute(f'select * from {get_inv()}.device')
+    if not list(devices):
+        return
+
     init_app()
     remove_manual_actions()
     change_lot()