I have been doing a lot of work in my console for this app and it just started acting strangely. There are a number of weird behaviors, but the one that is most irritating is that when I type in Joke.last to try to get the most recently-inputted joke from my app, it gives me the joke with id: 1.
Has anyone experienced this? I have tried restarting my server and my console.
What is the SQL output of Joke.last? You might have a re-defined default order, which take precedence over the order by id desc added by .last method.
I've inherited some code written in ruby 1.8.7 with Rails ~> 2.3.15 and it contains a test which looks something like this:
class Wibble < ActiveRecord::Base
# Wibbles have integer primary keys and string names
end
def test
create_two_wibbles
w1 = Wibble.first
sleep 2 # This sleep is necessary to
w2 = Wibble.first
w1.name = "Name for w1"
w2.name = "Name for w2"
w1.save
w3 = Wibble.first
assert(!w3.update_attributes(w2.attributes))
end
That comment next to the sleep line hasn't been cut off, it literally says This sleep is necessary to. Without that sleep, this test fails - removing it changes the behaviour somehow beyond making it run 2 seconds faster. I've been digging through the file's history in our version control system, and the messages were uninformative. I also cannot contact the original author of this test to figure out what they were trying to do.
From my understanding, we're pulling the same record out of the database twice, editing it in two different ways, saving the first, and asserting that we can't then save the second. I suspect this is a test to make sure our database locks the table correctly, but surely if this were to fail our Wibbles would be fine, and ActiveRecord would be at fault. Nobody in the office can figure out why this test may have been necessary, nor what difference the sleep statement might make. Any ideas?
This is likely caused by Active Record caching and memoization stopping the second find from actually going to the DB and get fresh data.
In fact, try printing the object_id of each wibble; they might be the exact same memoized object. If that is the case, then the test kinda makes sense.
You could also do the same test in a controller action and look at the verbose SQL logs from Rails; I'd expect the second find call to tell you it just used cached data and did not actually run any SQL query.
I have a Rails 3 app that has several hundred records in a mySQL-DB that need to be updated multiple times each hour. The actual updating is done through delayed_job which is triggered in controller-logic (checking if enough time has passed since the last update, only then sth. happens).
Each update is slow, it can take up to a second in some cases (although it averages at 3 - 5 updates/sec.).
Code looks like this:
class Thing < ActiveRecord::Base
...
def self.scheduled_update
Thing.all.each do |t|
...
t.some_property = new_value
t.save
end
end
end
I've observed that the execution stalls after 300 - 400 records and then the delayed job just seems to hang and times out eventually (entries in delayed_job.log). After a while the next one starts, also fails, and so forth, so not all records get updated.
What is the proper way to do this?
How does Rails handle database-connections when used like that? Could it be some timeout issue that is not detected/handled properly?
There must be a default way to do this, but couldn't find anything so far..
Any help is appreciated.
Another options is update_all.
Rails is a bad choice for mass data records. See if you can create a sql stored procedure or some other way that would avoid active record.
Use object.save_with_validation(false) if you are ok with skipping validations altogether.
When finding records, use :select => 'a,b,c,other_fields' to limit the fields you want ('a', 'b', 'c' and 'other' in this example).
Use :include for eager loading when you are initially selecting and joining across multiple tables.
So I solved my problem.
There was some issue with the rails-version I was using (3.0.3), the Timeout was caused by some bug I suspect. Updating to a later version of the 3.0.x branch solved it and everything runs perfectly now.
Hey everyone... I've been out of the game for awhile so you're going to have to excuse the fact that it's Rails2.3
Currently the app is running 2.3.3, I just updated it to 2.3.11
An object is edited, and saved using the .save command and the SQL generated in the logs is as follows:
UPDATE `calc_sheets` SET `is_us_connection` = 0, `holding_date_end` = '0001-02-11', `updated_on` = '2011-03-16 13:14:00', `extra_chars` = '' WHERE `id` = 657
however for some reason the created_on field is getting updated, and obviously shouldn't be. Is there some bug that I'm not aware of. I did some searching, looking and reading and nothing jumped out at me.
This is the only SQL call made during the action, so it's not as if something else is being updated or saved.
Any advice?
I realize this is out dated code, the app is fairly old, and the clients aren't ready to updated it... this "bug" however is causing all kinds of havoc.
Thanks in advance for any advice.
My guess is that the created_on table column is set to on "on update CURRENT_TIMESTAMP" (assuming mySQL) or something equivalent.
I'm trying to update one of my objects in my rails app and the changes just don't stick. There are no errors, and stepping through with the debugger just reveals that it thinks everything is updating.
Anyway, here is the code in question...
qm = QuestionMembership.find(:first, :conditions => ["question_id = ? AND form_id = ?", q_id, form_id])
qm.position = x
qm.save
For reference sake, QuestionMembership has question_id, form_id, and position fields. All are integers, and have no db constraints.
That is basically my join table between Forms and Questions.
Stepping through the code, qm gets a valid object, the position of the object does get changed to the value of x, and save returns 'true'.
However, after the method exits, the object in the db is unchanged.
What am I missing?
You may not be finding the object that you think you are. Some experimenting in irb might be enlightening.
Also, as a general rule when changing only one attribute, it's better to write
qm.update_attribute(:position, x)
instead of setting and saving. Rails will then update only that column instead of the entire row. And you also get the benefit of the data being scrubbed.
Is there an after_save?
Is the correct SQL being emitted?
In development log, you can actually see the sql that is generated.
For something like this:
qm = QuestionMembership.find(:first, :conditions => ["question_id = ? AND form_id = ?", q_id, form_id])
qm.position = x
qm.save
You should see something to the effect of:
SELECT * FROM question_memberships WHERE question_id=2 AND form_id=6 LIMIT 1
UPDATE question_memberships SET position = x WHERE id = 5
Can you output what sql you are actually seeing so we can compare?
Either update the attribute or call:
qm.reload
after the qm.save
What is the result of qm.save? True or false? And what about qm.errors, does that provide anything that makes sense to you? And what does the development.log say?
I have run into this problem rather frequently. (I was about to say consistently, but I cannot, as that would imply that I would know when it was about to happen.)
While I have no solution to the underlying issue, I have found that it seems to happen to me only when I am trying to update mysql text fields. My workaround has been to set the field to do something like:
qm.position = ""
qm.save
qm.position = x
qm.save
And to answer everyone else... when I run qm.save! I get no errors. I have not tried qm.save?
When I run through my code in the rails console everything works perfectly as evidenced by re-finding the object using the same query brings the expected results.
I have the same issue when using qm.update_attribute(... as well
My workaround has gotten me limping this far, but hopefully someone on this thread will be able to help.
Try changing qm.save to qm.save! and see if you get an exception message.
Edit: What happens when you watch the log on the call to .save!? Does it generate the expected SQL?
Use ./script/console and run this script.. step by step..
see if the position field for the object is update or not when you run line 2
then hit qm.save or qm.save!... to test
see what happens. Also as mentioned by Tim .. check the logs
Check your QuestionMembership class and verify that position does not have something like
attr_readonly :position
Best way to debug this is to do
tail -f log/development.log
And then open another console and do the code executing the save statement. Verify that the actual SQL Update statement is executed.
Check to make sure your database settings are correct. If you're working with multiple databases (or haven't changed the default sqlite3 database to MySQL) you may be working with the wrong database.
Run the commands in ./script/console to see if you see the same behavior.
Verify that a similar object (say a Form or Question) saves.
If the Form or Question saves, find the difference between the QuestionMembership and Form or Question object.
Turns out that it was emitting the wrong SQL. Basically it was looking for the QuestionMembeship object by the id column which doesn't exist.
I was under the impression that that column was unnecessary with has_many_through relationships, although it seems I was misguided.
To fix, I simply added the id column to the table as a primary key. Thanks for all the pointers.