Many-To-Many Joins

[Necoro]

Currently it seems to not be possible to use many-to-many joins in diesel. I was unable to find some out-of-the-box "many-to-many from A to B via cross-table C" -- and for manual implementation (one-to-many from A to C, many-to-one from C to B) support for id-less tables (C obiously has a compound PK) is missing.

Thus, I wanted to open this issue as a reminder (I'm quite astonished that there is none yet :))

[sgrif]

Thanks for the issue! This pretty much falls naturally out of the current design once we add composite PK support in general, which is something I'm working on.

[cbrewster]

Hi @sgrif, is there anywhere where I can track the progress of composite PK support?

[killercup]

A bunch of stuff for composite PKs landed recently, like the annotations in `table!`. Have a look at the release notes, or the PRs for that if the macro docs don't include it. Connor Brewster <notifications@github.com> schrieb am Di. 27. Dez. 2016 um 05:14:

…

Hi @sgrif <https://github.com/sgrif>, is there anywhere where I can track the progress of composite PK support? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#398 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AABOX8_cLrKInwL9pZP69z3uh8UrRCETks5rMJCfgaJpZM4JfVsd> .

[cbrewster]

@killercup awesome! Is there a recommended way to handle many-to-many yet or is that still in the works?

[lholden]

@cbrewster @killercup The composite stuff works... but many to many stuff is still messy by the looks of it.
An example of specifying a composite key in the table! macro:

table! {
    firsts_seconds (first_id, second_id) {
        first_id -> Integer,
        second_id -> Integer,
    }
}

And then I guess you can do a join query on the firsts_seconds and seconds where the first_id matches the id of the first you are starting with.

[Kerollmops]

Hi everybody !

Is there some news on many-to-many joins ?
I noticed that infer_schema! only supports tables with primary keys and that's not mandatory for many-to-many joins.

Therefore I don't know how to represent simple tables joins between Users and Teams (for example).

Thanks ❤️

EDIT: Ooops! It seems the table! macro can help me...