On Monday, March 5, 2018 at 12:18:42 PM UTC-8, [email protected] wrote: > > b2.foo = f2 >> # raises Sequel::Error: associated object #<Foo @values={}> does not have >> a primary key >> >> After fixing those issues, let's consider f3.bars. f3 is basically just >> Foo[1], since b3.foo_id is 1. Foo[1].bars doesn't return [f2], it returns >> [b2]. It should never return f2 or f3 because it returns instances of Bar, >> not of Foo. If you are asking if f3.bars should return [b2, b3], no, >> because b3 hasn't been saved to the database yet. >> > > I think reciprocal is a good concept, but I don't understand why it works > in some cases and not in others. Loos at the first example. A simple f.bars > before b2.foo = f2 assignment resolves well the reciprocal. But if you do > without first loading bars, reciprocal assignation is avoided. It doesn't > depend of persisted objects. >
That's correct, if you have code like: f2 = Foo.create b2 = Bar.new f2.bars b2.foo = f2 f2.bars # => [b2] then f2.bars returns b2 even though b2 hasn't been persisted yet, because an association modification method was called on the reciprocal object (b2.foo=). > Second case is, pehaps, subtle, but I think the object representation > (with reciprocals) doesn't depend in Sequel of persisted state, but in this > case it seems so. > The difference in the b3 case is that an association modification method is not called, only an association retrieval method. Association retrieval methods don't modify existing reciprocals, since they return new objects, and only set the reciprocal object in the returned object in certain cases, most commonly when you do: foo = Foo[1] foo.bars.each |bar| bar.foo # already set end The many_to_one association doesn't generally set reciprocals on returned objects. When you do: f3 = b3.foo # f3.bars not already set f3.bars cannot be set in such a case, because you don't actually know which bars are associated to f3 without doing a query. You seem to want to Sequel to do the query to get the bars for f3, and then after the query, add b3 to the results because it was the object used to retrieve f3. That's not how Sequel works, and I'm not sure the behavior is desirable. It is probably something you could do in a custom plugin, so I would go down that route if that is the behavior you want. Thanks, Jeremy -- You received this message because you are subscribed to the Google Groups "sequel-talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sequel-talk. For more options, visit https://groups.google.com/d/optout.
