Posted by Thomas Brodt on Nov 04, 2020; 10:17am
URL: https://forum.world.st/Filling-a-Collection-with-alsoFetch-still-materializes-Proxies-tp5124357p5124369.html

Your query fetches Garages and you do an alsoFetch: of wheels, but not of the cars. Maybe you have a retrieve: [:g | g car] that isn't mentioned in the mail, that would change the query output to cars. If you add

q alsoFetch: [:g | g car "or cars?"]

to the query (not to the mapping) does this help?

So you should have

Thomas

Hi there,

I have this weird thing I don't understand. For a GUI component I issue a query like this (very simplified):

q := SimpleQuery read: Garage where: [:g| g cars anySatisfy: [:c| color = 'silver']].

q alsoFetch: [:g| g car wheels asOuterJoin].

myCarCollection := self session execute: q.

Obviously, I am talking about a OneToManyRelationship here.

So once this collection of cars is read from the database, it is displayed in a list to the user. IN the list I want to display whether the car has wheels or not.

Now to the "funny" effect. Each car will then issue an SQL statement like this whenever the getter #cars of a Garage is accessed:

SELECT t1.id, ...
FROM WHEEL WHERE CAR_ID = "the id of a car"

So it seems that even though my initial search/query joins the Garage, Car and Wheel table, the cars will hold a Proxy in their wheels inst var.

In our not so simple productive case, this means that some lists take a long time to render because it issues a few hundred SQL statements for data that has already been read in the first query.

I already tried tried #shouldProxy: false in the OneToManyMapping for the car's wheels attribute, but to no avail. Even adding the alsoFetch: to the Garage's #cars mapping doesn't avoid these extra SQLs. (and it may be a tricky optimization that strikes back whenever the wheels of cars in a garage aren't needed....)

Any ideas what I can do?

Joachim

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