rom-rb/chat

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Oskar Szrajer

@gotar

{a: 1, b: 2}[:a]

and

def [](id)
   ...
end

user[12] # => is like user.find_by_id(12)

not sure it's the best explanation

[6] pry(main)> add = -> (a,b) { a + b}
=> #<Proc:0x00005567f9a1eee0@(pry):6 (lambda)>
[8] pry(main)> add.call(1,2)
=> 3
[9] pry(main)> add.(1,2)
=> 3
[10] pry(main)> add[1,2]
=> 3

Oskar Szrajer

@gotar

so when you used to use [] in a hash, in a procs it's somehow natural (for me) to use like users[12] #=> give me user by ID equal 12

hope it answers to your question somehow

Ethan Turkeltaub

@ethnt

Yes, that makes sense! I was just curious about the backstory :)

Oskar Szrajer

@gotar

for real backstory you will need to do a git blame and find the authors :p

but I hope it gives you some explanation ;]

Piotr Solnica

@solnic

another concept is to use .() shortcut for objects that are pure (so no side-effects), but I failed to use it like that consistently :) I just like typing .() instead of .call :D

S.Tamiya

@ablce9

I have a question here. Basically I have three tables and need to left-join two of them. SQL here MySQL [account]> select email,role,main_email from users left join tenants_users on (tenants_users.user_uuid = users.uuid) left join tenants on (tenants.main_email = users.email);.
I got this instead,

[86] pry(main)> db.from(:users).select(:email).left_join(:tenants_users, user_uuid: :uuid).select_append(:role).left_join(:tenants, main_email: :email)
=> #<Sequel::Mysql2::Dataset: "SELECT `email`, `role` FROM `users` LEFT JOIN `tenants_users` ON (`tenants_users`.`user_uuid` = `users`.`uuid`) LEFT JOIN `tenants` ON (`tenants`.`main_email` = `tenants_users`.`email`)">

I like to replace tenants_users.email with users.email.

I wonder how I can explicitly write left join tenants on (users.email = tenants.main_email) ???

Oskar Szrajer

@gotar

@ablce9 left_join(:tenants, { main_email: :email }, table_alias: :users) i guess

Nikita Shilnikov

@flash-gordon

this is falling back to sequel, rom-sql from master has first class support for it. ATM releasing a matter of a couple of months

Oskar Szrajer

@gotar

but that should do the job as I know

@flash-gordon and how new ROM support for this looks like?

Nikita Shilnikov

@flash-gordon

it's on the changelog

Oskar Szrajer

@gotar

ok :)

Nikita Shilnikov

@flash-gordon

there should be nice examples

Oskar Szrajer

@gotar

yeah :) nice one thx

S.Tamiya

@ablce9

@flash-gordon Thanks. I somehow figures using Sequel.lit(users.email).

ohh, sorry @gotar

Oskar Szrajer

@gotar

Sequel.lit() generally should never be used (all should be achievable in ROM, without calling Sequel directly)

S.Tamiya

@ablce9

Yeah, but this is one time only. The code is meant for a migration.

Nikita Shilnikov

@flash-gordon

I actually write migrations in pure SQL :)

data migrations I mean

S.Tamiya

@ablce9

The project I'm working on generally stores migration file around db/migration . Is that common to write pure SQL when doing migration?

Nikita Shilnikov

@flash-gordon

well, depends on your SQL skills :) Data migrations are kind of one-way anyway and I don't want anything between me and database during the migration. And it's usually faster

personally, I wrote a lot of SQL so this is a non-issue for me

S.Tamiya

@ablce9

I realized it's really tricky converting SQL code into Sequel. and what worse is Sequel is not that supportive I guess? so I come here and ask for helps and people here are really supportive, thanks.

Nikita Shilnikov

@flash-gordon

We discourage from Sequel when possible, our plan is provide people with the tools required for that

Sequel is sort of low level in general and leaks too much SQL related stuff

OTOH migrations is a different beast

esp data migrations

S.Tamiya

@ablce9

gotcha!

Ethan Turkeltaub

@ethnt

Hi guys, another question. I have a recursive relation: a country has many regions, which has many regions. is there a way to recursively get all of the regions of a country?

countries_repositories.aggregate(region: :region) gets the first two layers but not below that

Piotr Solnica

@solnic

@ethnt there's no special feature to cover this. You could write some smart query yourself to get it effectively.

Ethan Turkeltaub

@ethnt

@solnic Good to know, thanks :+1:

Ethan Turkeltaub

@ethnt

@solnic I guess in a similar vein, is there a recommendation for trees in ROM or just use self-referential associations?

Piotr Solnica

@solnic

I used tree extension in PG for that

Ethan Turkeltaub

@ethnt

If only I could use PG 🙃stuck on MySQL

Piotr Solnica

@solnic

@ethnt that's unfortunate, because the implementation in PG was like few lines of code, I really liked it

we even have a special type for ltree: https://github.com/rom-rb/rom-sql/blob/master/lib/rom/sql/extensions/postgres/types/ltree.rb it gives you custom API for queries like people.select(:name).where { ltree_tags.match_any(['Bottom', 'Bottom.Cities.*']) } :)

Mihai Radulescu

@mihairadulescu

hey guys did anyone experienced lately MySql connection has Gone away when using rom.rb in Aurora Db Mysql ?

Nikita Shilnikov

@flash-gordon

I don't think this kind of issues could be directly related to rom, although it's possible databases close connections after a certain timeout. I know that Sequel has a workaround for that and I'm pretty it sure you can use it with rom

assuming my guess is right ofc

http://sequel.jeremyevans.net/rdoc-plugins/files/lib/sequel/extensions/connection_validator_rb.html

this is an example of building a container with extensions https://github.com/rom-rb/rom-sql/blob/b1ebc39e913e4bd50c886e96da33ec768ba2818e/lib/rom/sql/gateway.rb#L52

Mihai Radulescu

@mihairadulescu

already have that connection validator in place.

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