Placeholders in Relation callback

[arvidfm]

It would be nice if placeholders used inside Relation callbacks resolved to the table corresponding to the relation rather than the root model, e.g.:

var card Card
db.NewSelect().Model(&card).
    Relation("Card.Deck.Collection", func(query *bun.SelectQuery) *bun.SelectQuery {
        // ?TableAlias.name should resolve to card__deck__collection.name; currently resolves to card.name
        return query.Where("?TableAlias.name = ?", collectionName)
    })

Possibly related to #154.

[imraan-go]

I think this "Where" clause should be appended after join instead of at the end of the query. More details on this issue: #554

@vmihailenco any comment on this ?

[fiftin]

@arvidfm , @vmihailenco

We need to come up with a syntax for this feature. Currently I will do like in issue description.

But I think we should replace ?TableAlias to something without ?.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. If there is no update within the next 7 days, this issue will be closed.