objectbox-java
objectbox-java copied to clipboard
objectbox
@Unique: more on conflict options
@Unique currently supports FAIL and REPLACE that are compatible with Sync.
Proposal to add more options (that likely will not work with Sync):
@Unique(onConflict=IGNORE): ignore the offending object (no changes to the existing conflicting object). If there are multiple unique properties in an entity, this strategy is evaluated first:
if the property conflicts, no other properties will be checked for conflicts.
@Unique(onConflict=UPDATE): the offending object overwrites the existing conflicting object while keeping its ID. Thus, all relations pointing to the existing entity stay intact.
This is useful for a "secondary" ID, e.g. a string "ID". Within an entity, this strategy may be used once only (update target would be ambiguous otherwise).
Multiple strategies in an entity are processed in this order: IGNORE, FAIL, REPLACE, UPDATE.
Originally posted by @greenrobot in https://github.com/objectbox/objectbox-java/issues/509#issuecomment-425055199
As stated on #509, my own use case can't rely on FAIL not REPLACE, but needs IGNORE.
Implementing the current issue is enough in most cases, maybe in all cases. These options are extremely necessary and a must-have for many projects.
But what you think if user can himself decide the priority?
@Unique(onConflict=IGNORE, priority=4)
var name: String = ""
@Unique(onConflict=FAIL, priority=3)
var address: String = ""
@Unique(onConflict=REPLACE, priority=2)
var phone: String = ""
@Unique(onConflict=UPDATE, priority=1)
var lastSeen: Long = 1234567890
The put() operation would be done according to the highest priority.
The UPDATE strategy would be very useful for me. Currently I have to manually implement the update mechanism by running a query() for each object in a list, then set all the fields if an existing is found. The performance is not the end of the world, but I get a lot of log spam and the code looks ugly.
@chakflying
then set all the fields
This sounds like the existing REPLACE strategy could work for this, no? https://docs.objectbox.io/entity-annotations#unique-constraints
I would like to move the discussion about my new proposal here. https://github.com/objectbox/objectbox-java/issues/1046
@greenrobot-team But REPLACE doesn't automatically update the relations? If I have to check whether it got replaced during insert, then fix the relations manually it would be even more messy, I think.
Hello, there is some news? still need that implementation of ConflictStrategy.UPDATE @greenrobot-team
Has there been any update about ConflictStrategy.UPDATE in the meanwhile? @greenrobot-team
@deliqs What's your use case? E.g. why can't put be used in your case?
@greenrobot-team I'm building an offline first mobile app. I link the local/offline data to the central/online data by saving the central PK locally as a separate identifier once the data has been uploaded. I want to keep the local data in sync with the central data. So I currently check if any data is missing or outdated locally and get the missing/updated data from my central database.
Please correct me if I'm wrong, but as far as I can see ConflictStrategy.REPLACE will also replace the existing local PK, and thus breaking all existing relationships. So I have to map the data from my central database on to the corresponding local data. It would be a improvement to the code if I could instead just update the local data by inserting the new data with the matching ConflictStrategy.UPDATE property without breaking the existing relationships.
@deliqs Thanks for the details! Yes, if a replace occurs with ConflictStrategy.REPLACE the new inserted object will have a different @Id. And relations would still point to the removed objects @Id, so would be broken.
I'm also looking forward to use this kind of UPDATE strategy. Is there any target date for releasing that feature?
@Schmalztopf No, we will share once a feature is being worked on and when it's done. To help us track interest, thumbs up the first post.