Update if exists

[NightZpy]

How avoid create new if data already exists?

[ricekab]

I did plan to have this behavior but I don't think I ever implemented it.

This would be pretty useful and isn't actually that hard to add.

I'll add it to the 0.4.0 milestone which should be release ready in the coming days (once I find some time to update the docs)

[ricekab]

Should be as simple as using merge instead of add, based on the documentation: http://docs.sqlalchemy.org/en/latest/orm/session_state_management.html#merging

[shashanksheela]

@ricekab Any update on this issue?

[ricekab]

I just did a quick test replacing session#add with session#merge but didn't get it to work properly. You can take a look in the feat/merge-existing-data (3c7594b) if you want to take a look at it. It passes the same tests as with add (there is another failure that needs to be looked at).

In the end, using merge might not be what we end up going with since it's based on the primary key. Which in most seeding cases you either don't know or don't want to be tied to. Perhaps simply doing a lookup with all the data provided should be sufficient to determine if it's existing or not?

[shashanksheela]

Thanks for the reply!!

It worked by changing session.add to session.merge.

[ricekab]

Huh, that's peculiar since the test actually doesn't pass. Unless I did something wrong in the test case itself. I'll have to take another look at it.