Use `viewonly=True` to suppress relationship warnings in SQLA 1.4

pokedex/db/multilang.py

@@ -185,6 +185,7 @@ def create_translation_table(_table_name, foreign_class, relation_name,
         foreign_keys=[Translations.foreign_id, Translations.local_language_id],
         uselist=False,
         lazy=relation_lazy,
+        viewonly=True,
     ))
 
     # Add per-column proxies to the original class

pokedex/db/tables.py

@@ -30,6 +30,7 @@ from functools import partial
 import six
 
 from sqlalchemy import Column, ForeignKey, MetaData, PrimaryKeyConstraint, UniqueConstraint
+from sqlalchemy import __version__ as sqla_version
 from sqlalchemy.ext.declarative import declarative_base, DeclarativeMeta
 from sqlalchemy.ext.associationproxy import association_proxy
 from sqlalchemy.ext.hybrid import hybrid_property
@@ -39,6 +40,12 @@ from sqlalchemy.types import Boolean, Enum, Integer, SmallInteger, Unicode, Unic
 
 from pokedex.db import markdown, multilang
 
+relationship = partial(relationship, viewonly=True)
+if (1, 3, 17) <= tuple(int(x) for x in sqla_version.split(".")) < (1, 4):
+    # `sync_backref` was introduced in 1.3.17
+    # Since 1.4 it defaults to False if `viewonly` is True
+    relationship = partial(relationship, sync_backref=False)
+
 class TableSuperclass(object):
     """Superclass for declarative tables, to give them some generic niceties
     like stringification.