fix migration for old sqlite

1 files changed, 17 insertions, 2 deletions

diff --git a/fietsboek/alembic/versions/20221214_c939800af428.py b/fietsboek/alembic/versions/20221214_c939800af428.py
index eed8bab..79ec899 100644
--- a/fietsboek/alembic/versions/20221214_c939800af428.py
+++ b/fietsboek/alembic/versions/20221214_c939800af428.py
@@ -7,6 +7,7 @@ Create Date: 2022-12-14 23:58:37.983942
 """
 from alembic import op
 import sqlalchemy as sa
+import logging
 
 
 # revision identifiers, used by Alembic.
@@ -17,10 +18,24 @@ depends_on = None
 
 def upgrade():
     # ### commands auto generated by Alembic - please adjust! ###
-    op.drop_column('tracks', 'gpx')
+    try:
+        op.drop_column('tracks', 'gpx')
+    except sa.exc.OperationalError:
+        # sqlite < 3.35.0 does not know "ALTER TABLE DROP COLUMN", in which
+        # case we probably don't want to break the DB. Instead, we simply
+        # "drop" the column by setting it empty, which should still help in
+        # saving some space.
+        logging.getLogger(__name__).warning(
+            "Your database does not support dropping a column. "
+            "We're setting the content to zero instead."
+        )
+        op.execute("UPDATE tracks SET gpx = '';")
     # ### end Alembic commands ###
 
 def downgrade():
     # ### commands auto generated by Alembic - please adjust! ###
-    op.add_column('tracks', sa.Column('gpx', sa.BLOB(), nullable=True))
+    try:
+        op.add_column('tracks', sa.Column('gpx', sa.BLOB(), nullable=True))
+    except sa.exc.OperationalError:
+        logging.getLogger(__name__).warning("The column already exists.")
     # ### end Alembic commands ###