I'm having a strange problem in Rails with a Postgres query.
The query looks something like this:
WeeklyPlanner.find_or_create_by_user_id(current_user.id).recipes.find(:all,
:conditions => ["
weekly_planner_events.time_start =
date_part('epoch', to_timestamp(?)::timestamptz at time zone 'CDT')",
Time.local(Time.now.year, Time.now.month, Time.now.day).to_i
])
This generates (as I can view in the console), the following SQL statement:
SELECT "recipes".* FROM "recipes"
INNER JOIN "weekly_planner_events" ON "recipes"."id" = "weekly_planner_events"."recipe_id"
WHERE "weekly_planner_events"."weekly_planner_id" = 2
AND (weekly_planner_events.time_start = date_part('epoch', to_timestamp(1347426000)::timestamptz at time zone 'CDT'))
My problem is that the generated SQL statement works well on psql or pgAdmin, but on rails it returns an empty array. That is, if I copy and paste it as is on a postgres console, it works perfectly fine, but when I run it on the Rails console, it returns nothing, and I have no idea why its happening.
I've tried the following:
Parametrizing 'epoch' and 'CDT'/timezone (in order to remove 's
Switching to a where statement, with the same condition
Passing the variables with #{}s
Doing the search without the date_part('epoch', [float]) function works fine in Rails, but its obviously not the result I need.
I'm finding this issue quite confusing, if there is any other data you need please let me know and I will edit the post.
Thank you.
Maybe when you are using the find_or_create method it is using the create action, so you create a new WeeklyPlanner for a user, and this brand new WeeklyPlanner doesn't have recipes attached to it because it has just been created.
When you go to psql, you probably use a existent WeeklyPlanner.
But this is just a guess.
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've not played with Ruby in a while, and was just writing a simple db query tool.
The tool connects fine and returns the correct number of results for the query (56 rows in this case), but the value returned for each element is 'nil'. Executing the query in sqlplus works fine.
I've found similar problems on StackExchange, but most of the solutions don't apply, or require using ODBC directly. Ugh.
I'm including a stripped down version of what I've written. Any ideas what I'm doing wrong?
require 'dbi'
dbh = DBI.connect('DBI:OCI8:foodb', 'user', 'password')
rs = dbh.prepare('select field_name from foo_user.cdr_fields where layout like ?')
rs.execute('phi_outage')
while rsRow = rs.fetch do
p rsRow
end
rs.finish
dbh.disconnect
The fetch method is an iterator so no need for a while loop. Try
rs.fetch do|row|
p row unless p.nil?
end
The API states that the method gets called for all remaining rows and will return nil when done.
So I have an table of phone_numbers in Rails 3.2, and I would like to be able to make a query such as the following:
PhoneNumber.where("last_called_at - #{Time.now} > call_spacing * 60")
where last_called_at is a datetime and call_spacing is an integer, representing the number of minutes between calls.
I have tried the above, I have also tried using
PhoneNumber.where("datediff(mi, last_called_at, #{Time.now}) > call_spacing")
If anyone could help me make this work, or even recommend a current, up-to-date rails SQL gem, I would be very grateful.
Edit: So the best way to make this work for me was to instead add a ready_at column to my database, and update that whenever either call_spacing or last_called_at was updated, using the before_save method. This is probably the most semantic way to approach this problem in rails.
You have to use quotes around #{Time.now}. To make your first query work you may use TIME_TO_SEC() function:
PhoneNumber.where("(TIME_TO_SEC('#{Time.now}') - TIME_TO_SEC(last_called_at)) > (call_spacing * 60)")
Here is my way to do this:
PhoneNumber.where("last_called_at > '#{Time.zone.now.utc - (call_spacing * 60)}'")
also take a look at this article to be aware of how to play with timezones:
http://danilenko.org/2012/7/6/rails_timezones/
I'm having a strange issue when using the Where clause in Rails. I imagine it has something to do with my OR operator syntax. Here is my query:
Cookie.where("ID = ? OR ID = ? OR ID = ? OR ID = ?", chocolate.to_s, sugar.to_s, peanut_butter.to_s, oatmeal.to_s)
When I attempt to execute the query my application just hangs endlessly. However, If I submit a query that looks like this:
Cookie.where("ID = ?", chocolate.to_s)
I get the expected result. Any help with the proper format to this where clause would be greatly appreciated. Thanks.
UPDATE
I went into the rails console and did as you suggested. This was the result:
SELECT \"TBLCookies\".* FROM \"TBLCookies\" WHERE (ID in ('4','3','2','1'))
This seems correct. I opened up SQL Developer, pasted this query in, and ran it. I got the expected result. So everything seems to be fine there. However, when I try to run the query in the rails console I get nothing back. The console just hangs indefinitely. Any insight into what could be going wrong would be great.
Why not do this
Cookie.where("ID in (?)",[chocolate, sugar, peanut_butter, oatmeal].collect(&:to_s))
I am trying to use the Arel#extract method. I have seen an example in a test case in test_extract.rb in the source but when I try to reproduce it in my app, I get undefined method.
table = Arel::Table.new :users
puts table[:created_at].extract('hour').to_sql
=> NoMethodError: undefined method `extract' for #<Arel::Attributes::Attribute:0x7..8>
I am using pg as the database.
Update:
My goal is to end up with this result in sql:
SELECT users.* FROM users WHERE EXTRACT(HOUR from users."created_at") = '1'
I would like to find all users that were created on the hour equal to one of any day. This works in sql but I am wondering how to create it in arel. Here is an example of how it's used in the arel test suite.
extract is node's method, you can cast it on any column(such as users[:id]), but not on Arel::Table instance.
So, to construct your query you need:
get Arel::Table instance users = Arel::Table.new(:users) or if you use ActiveRecord - users = User.arel_table
set SELECT statement on Arel::Table instance with project method: users = users.project(Arel.sql('*'))
set WHERE statement with where method: users.where(users[:created_at].extract(:hour).eq(1))
In one block:
query = User.arel_table.
project(Arel.sql('*')).
where(users[:created_at].extract(:hour).eq(1))
users = User.find_by_sql(query)
# => "SELECT * FROM \"users\" WHERE EXTRACT(HOUR FROM \"users\".\"created_at\") = 1"
I've had to perform an extract DOW on an instance of Arel::Nodes::NamedFunction, which does not expose the method #extract (as of Arel 6.0). I managed to achieve this by manually creating an instance of Arel::Nodes::Extract. Here is what worked for me, in case anyone have a similar issue:
Arel::Nodes::Extract.new(
Arel::Nodes::NamedFunction.new('some_function_name', [param1, param2, ...]),
:dow
)
You can use an Arel node directly with ActiveRecord's #where instead of building the full query through Arel as exemplified by Alexander Karmes's answer. So here is another way to perform the query required by the answer:
User.where(
Arel::Nodes::Extract.new(User.arel_table[:created_at], :hour).eq(1)
)
Which yields:
SELECT "users".* FROM "users" WHERE EXTRACT(HOUR FROM "users"."created_at") = 1
With the added benefit you can keep chaining other scopes defined in your User model.