ActiveRecord not writing to tables

rubyonrails-talk
1

I have two tables in MySQL: football_fixtures and weekly_fixtures. In my code I have two classes class FootballFixture end

and

class WeeklyFixture   has_many :football_fixtures end

the WeeklyFixture class has more code than this, mostly validation

In the console window I do this

wf = WeeklyFixture.new wf.somefield = somevalue wf.save!

and everything is OK

however if I do

wf = WeeklyFixture(6) # where 6 is an id in the table so the wf is found! wf.football_fixtures[0].name = "value" wf.save!

I get a return value of true, but no data is written to the database.

I have the log visible on another terminal (tail -f development.log), and I don't see any update call being made. (I do see selects being made when I read the records)

I think I'm missing something fundamental here. I assumed that when I updated the related fields and wrote the parent model the the DB then the save would also write the related fields, but this is not happening.

BTW, if I do wf.football_fixtures[0].save

that does work!

What (presumably simple) magic incantation am I missing?

Thanks,

Kevin Jones

2

When you do this code

wf = WeeklyFixture(6) # where 6 is an id in the table so the wf is found! wf.football_fixtures[0].name = "value" wf.save!

the wf has not been changed in any way. It point in the same football_fixtures item by its foreign key.

The football_fixtures has changed and you should save that change. That's done by your second sample.

3

Hi, there’s no magic happening. You’re simply invoking save on the wrong instance. Just because one invokes save on a parent instance it doesn’t automatically invoke save on its children. In most cases, this would be very inefficient. I would recommend learning/understanding more about ActiveRecord because this will help in the long run.

Good luck,

-Conrad

4

Thanks all,

so I was right. I was missing something fundamental :slight_smile:

Kevin