Implement app.oauthclients using relationship

backend/areas/apps/models.py

@@ -29,6 +29,7 @@ class App(db.Model):
     # The URL is only stored in the DB for external applications; otherwise the
     # URL is stored in a configmap (see get_url)
     url = db.Column(String(length=128), unique=False)
+    oauthclients = relationship("OAuthClientApp", back_populates="app")
 
     def __init__(self, slug, name, external=False, url=None):
         self.slug = slug
@@ -177,15 +178,6 @@ class App(db.Model):
             app_id=self.id
         ).all()
 
-    @property
-    def oauthclients(self):
-        """
-        All oauth clients related to this app
-        """
-        return OAuthClientApp.query.filter_by(
-            app_id=self.id
-        ).all()
-
     @property
     def kustomization(self):
         """Returns the kustomization object for this app"""
@@ -329,7 +321,7 @@ class OAuthClientApp(db.Model):  # pylint: disable=too-few-public-methods
     oauthclient_id = db.Column(String(length=64), primary_key=True)
     app_id = db.Column(Integer, ForeignKey("app.id"))
 
-    app = relationship("App")
+    app = relationship("App", back_populates="oauthclients")
 
     def __repr__(self):
         return (f"oauthclient_id: {self.oauthclient_id}, app_id: {self.app_id},"