J'ai quelques tables de notification différentes, et je voudrais effectuer une union à travers chacune d'elles pour montrer à l'utilisateur toutes leurs notifications. Cependant, le syndicat ne fonctionne pas comme il le devrait.Comment l'union entre plusieurs tables dans SQLAlchemy?
code Python
def _get_notifications_query(self, unconfirmed_only=True):
'''
Return base query to return this users notifications.
@param unconfirmed_only
@return Query object
'''
requests = (
DBSession.query(FriendshipRequestNotification)
.outerjoin(UserFriendshipRequestNotification,
UserFriendshipRequestNotification.notification_id==FriendshipRequestNotification.id)
.filter(UserFriendshipRequestNotification.user_id==self.id))
confirmations = (
DBSession.query(FriendshipConfirmationNotification)
.outerjoin(UserFriendshipConfirmationNotification,
UserFriendshipConfirmationNotification.notification_id==FriendshipConfirmationNotification.id)
.filter(UserFriendshipConfirmationNotification.user_id==self.id))
comments = (
DBSession.query(CommentNotification)
.outerjoin(UserCommentNotification,
UserCommentNotification.notification_id==CommentNotification.id)
.filter(UserCommentNotification.user_id==self.id))
if unconfirmed_only:
requests.filter(UserFriendshipRequestNotification.is_confirmed==False)
confirmations.filter(UserFriendshipConfirmationNotification.is_confirmed==False)
comments.filter(UserCommentNotification.is_confirmed==False)
return requests.union(confirmations, comments)
Utilisation: user._get_notifications_query (unconfirmed_only = False) .Toutes()
SQL généré
SELECT anon_1.friendship_request_notifications_id AS anon_1_friendship_request_notifications_id, anon_1.friendship_request_notifications_created_at AS anon_1_friendship_request_notifications_created_at, anon_1.friendship_request_notifications_requester_id AS anon_1_friendship_request_notifications_requester_id
FROM (SELECT friendship_request_notifications.id AS friendship_request_notifications_id, friendship_request_notifications.created_at AS friendship_request_notifications_created_at, friendship_request_notifications.requester_id AS friendship_request_notifications_requester_id
FROM friendship_request_notifications LEFT OUTER JOIN users_friendship_request_notifications ON users_friendship_request_notifications.notification_id = friendship_request_notifications.id
WHERE users_friendship_request_notifications.user_id = ? UNION SELECT friendship_confirmation_notifications.id AS friendship_confirmation_notifications_id, friendship_confirmation_notifications.created_at AS friendship_confirmation_notifications_created_at, friendship_confirmation_notifications.accepter_id AS friendship_confirmation_notifications_accepter_id
FROM friendship_confirmation_notifications LEFT OUTER JOIN users_friendship_confirmation_notifications ON users_friendship_confirmation_notifications.notification_id = friendship_confirmation_notifications.id
WHERE users_friendship_confirmation_notifications.user_id = ? UNION SELECT comment_notifications.id AS comment_notifications_id, comment_notifications.created_at AS comment_notifications_created_at, comment_notifications.comment_id AS comment_notifications_comment_id
FROM comment_notifications LEFT OUTER JOIN users_comment_notifications ON users_comment_notifications.notification_id = comment_notifications.id
WHERE users_comment_notifications.user_id = ?) AS anon_1
Je me attends quelque chose le long de ces lignes
SELECT * FROM friendship_request_notifications
UNION
SELECT * FROM friendship_confirmation_notifications
UNION
SELECT * FROM comment_notifications
De même, existe-t-il un moyen de trier les résultats d'union de SQLAlchemy?
EDIT
Je dois mentionner que sqlalchemy.sql.union()
produit SQL correct, mais je ne sais pas comment faire usage de ce de l'ORM (retour/compter les enregistrements).
Je dois construire des unions de plus de 2 requêtes, le nombre de requêtes en union est dynamique. sqlalchemy.sql.union() ne fonctionne pas. qu'est-ce que le syntaxt, je ne peux pas trouver dans doc – vishal