Details
Closed
Critical
Description
There are several problems with the current approach on fetch joins:
1. There is no way to determine in the parser already if a join is fetch or not, this makes it much harder to implement things like @OrderBy or @OrderColumn
2. A DQL like "SELECT u, g.name FROM User u JOIN u.group g" currently tries to partially load the group object instead of just returning g.name as scalar. This is very unintuiative.
Solution, change the EBNF too:
Join ::= ["LEFT" ["OUTER"] | "INNER"] "JOIN" [FETCH] JoinAssociationPathExpression ["AS"] AliasIdentificationVariable [("ON" | "WITH") ConditionalExpression]
Question would be how to specify partial object selects.
Romans idea was something like:
select u.{name, other, field, stuff}
However my take is this would again put information into the select clause that might be interesting elsewhere, so
SELECT u FROM User u JOIN FETCH u.group PARTIAL id, name
That way we could add both $isFetchJoin and $isPartial flags to the AST/Join Node plus an additional $partialFields array.
Issue Links
- is required for
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DDC-195
Ordering of associations
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Ah just to remember, the idea on the partial fetch syntax was something like:
select u FROM User u.{name, other, field, stuff} JOIN FETCH u.group g.{id, name, baz}