I'm trying to get the following request sanitized to send to a MySQL server:
INSERT INTO `table`
SELECT NULL, t.`id`, ?, ?
FROM `table` AS t
WHERE t.`some_field` = ?
The tricky part is that that request is to be executed in a class that is not my model class. It looks like this:
class Model < ActiveRecord::Base
def some_method
Service.new(self).run
end
end
class Service
def initialize(model)
#model = model
end
def run
# Here is the request
end
end
I've seen a lot of people using Model#sanitize_sql, but this is a protected method, which is unusable in my context.
Any idea?
EDIT:
It has been suggested that my question might be a duplicate of this one. I've seen this question before posting, but the answers provided there aren't relevant in my case: I don't want to use quote because most of my fields are going to be numeric values. The other answer suggests not using raw SQL, but, as stated in the comments, I don't think ActiveRecord is capable of generating an INSERT...SELECT query. (This question seems to confirm it)
Related
Im current working on a small project and I want to seed my database faster. I migrated a new column called "grand_total_points" to my table of users. So originally I was using this code.
user = User.all
user.each do |x|
x.grand_total_points = x.total_points
x.save!
end
This takes me ages, because I have to update a million record.
Total_points have already been defined in my user model where it calculates all the users points that have been submitted. Forgive me for my explanation. Is there a way to use update_all method but with each included in it?
Yep, possible:
User.update_all('grand_total_points = total_points')
It will generate the following SQL query:
UPDATE "users" SET "grand_total_points" = 'total_points'
If total_points is not a column but an instance method, move the logic into update_all query.
User.update_all("grand_total_points = #{total_points calculation translated into SQL terms}")
I found something that could work. So basically i combine a ruby code with an execute SQL statement, and I put it in a migration file. Here's how the code works. I hope this helps. Make sure you follow the query according to your data.
class ChangeStuff < ActiveRecord::Migration
def change
points = Point.select('user_id, SUM(value) AS value').group(:user_id)
points.each do |point|
execute "UPDATE users SET grand_total_points = #{point.value} WHERE users.id = #{point.user_id}"
end
end
end
You should run bundle exec rake db:migrate after that. The normal way takes me 2-3hours. This only took me 2minutes.
I have a table KmRelationship which associates Keywords and Movies
In keyword index I would like to list all keywords that appear most frequently in the KmRelationships table and only take(20)
.order doesn't seem to work no matter how I use it and where I put it and same for sort_by
It sounds relatively straight forward but i just can't seem to get it to work
Any ideas?
Assuming your KmRelationship table has keyword_id:
top_keywords = KmRelationship.select('keyword_id, count(keyword_id) as frequency').
order('frequency desc').
group('keyword_id').
take(20)
This may not look right in your console output, but that's because rails doesn't build out an object attribute for the calculated frequency column.
You can see the results like this:
top_keywords.each {|k| puts "#{k.keyword_id} : #{k.freqency}" }
To put this to good use, you can then map out your actual Keyword objects:
class Keyword < ActiveRecord::Base
# other stuff
def self.most_popular
KmRelationship.
select('keyword_id, count(keyword_id) as frequency').
order('frequency desc').
group('keyword_id').
take(20).
map(&:keyword)
end
end
And call with:
Keyword.most_popular
#posts = Post.select([:id, :title]).order("created_at desc").limit(6)
I have this listed in my controller index method which allows the the order to show the last post with a limit of 6. It might be something similar to what you are trying to do. This code actually reflects a most recent post on my home page.
I have an index view of a model which I would like to filter by some combination of the model's attributes.
For example, I have a Bill model (not the kind on ducks, the kind you have to pay) that I might filter on payee and/or status.
The model has a scope for each individual attribute, e.g.
scope :bill_status, lambda {|status| where("status = ?", status}
scope :bill_payee, lambda {|payee| where("payee_id = ?", payee.id}
The view allows the user to select zero or more options -- if an option is not selected, it means "don't filter by this".
In the controller, I can do something yucky like this:
def index
status = params[:bill][:status]
payee = params[:bill][:payee]
if status.present? and payee.present?
# chain scopes
#bills = Bill.bill_status(status).bill_payee(payee)
elsif status.present?
#bills = Bill.bill_status(status)
elsif payee.present?
#bills = Bill.bill_payee(payee)
else
#bills = Bill.all
end
# rest of controller action
end
But while this works, it's neither pretty nor easily extensible -- adding a third filter means I now have many more possibilities. I seek beauty and purity.
On the assumption that my scopes are all chainable, it seems like I should be able to do something like
def index
#bills = Bill.all
#bills = #bills.bill_status(params[:bill][:status]) if params[:bill][:status].present?
#bills = #bills.bill_payee(params[:bill][:payee]) if params[:bill][:payee].present?
# rest of controller code
end
'cept it doesn't work because Bill.all is an array. Plus, that's no fun because Bill.all executes the query, which I only want to run once thanks to AREL magic. Should I just define a scope like all_bills (with no conditions?) -- that would be an ActiveRecord::Relation I guess...
Is there a pattern that solves this problem more elegantly? Whenever I have code to do one thing that relies on Model, View and Controller I feel as though I might be doing something wrong. Or as though someone smarter and harder working than I has already solved it :-)
Bonus question: I want this all to work with my paginator of choice, the most excellent Kaminari gem.
All thoughts and ideas welcomed.
I'd do something like this:
proxy = Bill.scoped
if status.present?
proxy = proxy.bill_status(status)
end
if payee.present?
proxy = proxy.bill_payee(payee)
end
#bills = proxy
You can even do then some meta-programming:
#bills = [:status, :payee, ...].inject(Bill.scoped) do |proxy, param|
val = params[:bill][param]
val.present ? proxy.send("bill_#{param}", val) : proxy
end
As I searched for solutions to what seemed like a common problem, I checked out Ryan Bates' RailsCast and found an episode from 3 days ago on Ransack. Ransack is a pretty seriously cool gem for form searching and column sorting, and I think that's the way I am going.
Thanks for the answers here -- I am glad to have learned a couple of great techniques from those who took the time and effort the answer.
I have the following defined on my up method on my migration to set initial data:
def up
Color.create!({:id=>1,:name=>"",:color=>"FF6633"})
Color.create!({:id=>2,:name=>"",:color=>"93B233"})
Color.create!({:id=>3,:name=>"",:color=>"4D90D9"})
Color.create!({:id=>4,:name=>"",:color=>"C43092"})
end
Is there any truncate directive I can put on the down method like:
def down
Color.truncate
end
Or since I'm setting the IDs on the create should I use only the destroy_all method of the model Color ?
You can simple use this in your up method, this will solve your both truncate and id resetting problem also.
def up
ActiveRecord::Base.connection.execute("TRUNCATE table_name")
Color.create!({:id=>1,:name=>"",:color=>"FF6633"})
Color.create!({:id=>2,:name=>"",:color=>"93B233"})
Color.create!({:id=>3,:name=>"",:color=>"4D90D9"})
Color.create!({:id=>4,:name=>"",:color=>"C43092"})
end
Cheers!
Firstly, you don't have to pass :id into create! because ActiveRecord will automatically handle that, thus :id likely to get ignored (standard case assumed).
Secondly, it is not a good practice to use ActiveRecord query builder in migration because should the model Color name be changed, you are to have a broken migration. I highly recommend you to use pure SQL and execute that query with execute().
Thirdly, for the #down method, you shouldn't truncate the table. You should destroy those 4 colors that you created in #up.
Here's how I would write it:
def down
colors = ["FF6633", "93B233", "4D90D9", "C43092"]
Color.where(:color => colors).destroy_all
end
I'm using RoR and I want to do concurrency safe update queries. For example when I have
var user = User.find(user_id)
user.visits += 1
I get the following SQL code:
SELECT * FROM Users WHERE ID=1 -- find user's visits (1)
UPDATE Users SET Visits=2 WHERE ID=1 -- 1+1=2
But if there are several queries taking place at the same time, there will be locking problems.
According to RoR API I can use :lock => true attribute, but that's not what I want.
I found an awesome function update_counters:
User.update_counters(my_user.id, :visits => 1)
This gives the following SQL code
UPDATE Users SET Visits=Visits+1 WHERE ID=#something
Works great!
Now my question is how can I override the += function to do the update_counters thing instead?
Because
user.visits += 1 # better
User.update_counters(my_user.id, :visits => 1) # than this
UPDATE
I just created the following function
class ActiveRecord::Base
def inc(column, value)
User.update_counters(self.id, column => value)
end
end
Are there any other better ideas?
Don't know about better ideas, but I would define that method to the User class, not the ActiveRecord. And maybe increment_counter (that uses update_counters) would make it a bit more readable?
def inc(column, value)
self.increment_counter(column, value)
end
Haven't tested that and not saying this is definitely better idea, but that's probably how I'd do it.
Update:
And AFAIK you can't override the "+=", because "a += b" just a shortcut for "a = a + b" and you probably don't want to override "=" to use the update_counters :)