find in a nested object

[michalyad]

I have an object parent with nested children.

I read the parent from the data base by:
@parent=Parent.find_by_name("dani")

Thus I have all dani's children in @parent.

Now I would like to find "moshe" and update it.

When I write: @parent.children.find_by_name("moshe") it does a select
on the database although I shall have it memory.

When I wrtie a loop: @parent.children.each do.... then it does not go
to the database.

How can I do a find that will not do a select?

[Dimitri Krassovski]

A association in rails pretends to be a array when loaded, so calling array method on it works, but find_by_name is not a array method, so it's called on the association proxy instead, which doesn't know better than go to the db and do a conditional find.

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Dimitri Krassovski

[Elad Meidar]

parent = Parent.find_by_name("Elad", :include => :children)

Elad Meidar

http://blog.eizesus.com

http://twitter.com/eladmeidar

[Michal Yad-Shalom]

I would like to find a child with name "moshe" not a parent.

--
Michal Yad Shalom
054-4315617

[Dimitri Krassovski]

Do you only need the child?

Just do Child.find_by_name_and_parent_id

-- 

Dimitri Krassovski

[Michal Yad-Shalom]

I have already read the parent and all his children from the database. Now instead of writing a loop (@parent.children.each do...) to find a certain child, I would like to write a single find command that will not go to the database. 

Can I do this?

[Dimitri Krassovski]

@moshe = @parent.children.select{|c| c.name == "moshe"}.first

This should do it for you.

And, forgive me for my rudeness, go read a Ruby book when you're done.

[Elad Meidar]

and will raise an exception if there are no matches.

by using eager loading (either :include or :joins options) she'll be able to use Association#find without queries being made

Elad Meidar,
CEO, Nautilus6 Inc.
http://blog.eizesus.com
http://www.nautilus6.com

[Michal Yad-Shalom]

Dimitri Thanks.

BTW... your "rudeness" was in place.