I'm trying to join two different conditions on my Active Record Database.
Usually I'll join them with a comma (,) or AND, however in this case, putting a comma or AND between conditions is returning an error.
I wonder how to join those conditions together in one statement:
MyTable.where("created_at < ?", Time.now - 86400) # 86400 represent a day
MyTable.where(my_column: my_variable)
Thanks.
UPDATE
I'm using rails 4.
MyTable.where("created_at < ? AND my_column = ?", Time.now - 86400, my_variable)
Related
So i'm currently using the following command to join and query my tables - looking for an OrderItem amongst my Orders where the orderable_id = applicable_product_item_id the total_price = 0 and the buyer_id = current_user
Order.joins(:items)
.where(order_items: {id: OrderItem.where(orderable_id: applicable_product_item_id)})
.where(total_price: 0)
.where(buyer_id: current_user)
This all works fine, but now i want to query further and i want to know if the order that it has found has a created_at date > searchable_created_by_date
i've tried using another .where in the query as well as selecting the .first in the array and further querying that i.e. query = above_query.first
then
query.where("created_at > ?", searchable_created_by_date)
but i get
Undefined method where for #<Order:0x007fbc8d8edf90>
furman87's comment sounds right to me:
You'll have to specify the table in your where clause -- .where("orders.created_at > ?", searchable_created_by_date)
You might also try:
Order.
where(total_price: 0).
where(buyer_id: current_user).
where("created_at > ?", searchable_created_by_date).
joins(:order_items).
where(order_items: {id: OrderItem.where(orderable_id: applicable_product_item_id)})
I think putting the created_at statement before the joins statement will disambiguate the query - but I'm not 100% sure.
Also, I would have thought that you would have done joins(:order_items). But, I suppose that depends on how you have your associations set up. If joins(:items) works for you, then more power to you! (And ignore the comment.)
I have a Company model that has_many Statement.
class Company < ActiveRecord::Base
has_many :statements
end
I want to get statements that have most latest date field grouped by fiscal_year_end field.
I implemented the function like this:
c = Company.first
c.statements.to_a.group_by{|s| s.fiscal_year_end }.map{|k,v| v.max_by(&:date) }
It works ok, but if possible I want to use ActiveRecord query(SQL), so that I don't need to load unnecessary instance to memory.
How can I write it by using SQL?
select t.username, t.date, t.value
from MyTable t
inner join (
select username, max(date) as MaxDate
from MyTable
group by username
) tm on t.username = tm.username and t.date = tm.MaxDate
For these kinds of things, I find it helpful to get the raw SQL working first, and then translate it into ActiveRecord afterwards. It sounds like a textbook case of GROUP BY:
SELECT fiscal_year_end, MAX(date) AS max_date
FROM statements
WHERE company_id = 1
GROUP BY fiscal_year_end
Now you can express that in ActiveRecord like so:
c = Company.first
c.statements.
group(:fiscal_year_end).
order(nil). # might not be necessary, depending on your association and Rails version
select("fiscal_year_end, MAX(date) AS max_date")
The reason for order(nil) is to prevent ActiveRecord from adding ORDER BY id to the query. Rails 4+ does this automatically. Since you aren't grouping by id, it will cause the error you're seeing. You could also order(:fiscal_year_end) if that is what you want.
That will give you a bunch of Statement objects. They will be read-only, and every attribute will be nil except for fiscal_year_end and the magically-present new field max_date. These instances don't represent specific statements, but statement "groups" from your query. So you can do something like this:
- #statements_by_fiscal_year_end.each do |s|
%tr
%td= s.fiscal_year_end
%td= s.max_date
Note there is no n+1 query problem here, because you fetched everything you need in one query.
If you decide that you need more than just the max date, e.g. you want the whole statement with the latest date, then you should look at your options for the greatest n per group problem. For raw SQL I like LATERAL JOIN, but the easiest approach to use with ActiveRecord is DISTINCT ON.
Oh one more tip: For debugging weird errors, I find it helpful to confirm what SQL ActiveRecord is trying to use. You can use to_sql to get that:
c = Company.first
puts c.statements.
group(:fiscal_year_end).
select("fiscal_year_end, MAX(date) AS max_date").
to_sql
In that example, I'm leaving off order(nil) so you can see that ActiveRecord is adding an ORDER BY clause you don't want.
for example you want to get all statements by start of the months you should use this
#companey = Company.first
#statements = #companey.statements.find(:all, :order => 'due_at, id', :limit => 50)
then group them as you want
#monthly_statements = #statements.group_by { |statement| t.due_at.beginning_of_month }
Building upon Bharat's answer you can do this type of query in Rails using find_by_sql in this way:
Statement.find_by_sql ["Select t.* from statements t INNER JOIN (
SELECT fiscal_year_end, max(date) as MaxDate GROUP BY fiscal_year_end
) tm on t.fiscal_year_end = tm.fiscal_year_end AND
t.created_at = tm.MaxDate WHERE t.company_id = ?", company.id]
Note the last where part to make sure the statements belong to a specific company instance, and that this is called from the class. I haven't tested this with the array form, but I believe you can turn this into a scope and use it like this:
# In Statement model
scope :latest_from_fiscal_year, lambda |enterprise_id| {
find_by_sql[..., enterprise_id] # Query above
}
# Wherever you need these statements for a particular company
company = Company.find(params[:id])
latest_statements = Statement.latest_from_fiscal_year(company.id)
Note that if you somehow need all the latest statements for all companies then this most likely leave you with a N+1 queries problem. But that is a beast for another day.
Note: If anyone else has a way to have this query work on the association without using the last where part (company.statements.latest_from_year and such) let me know and I'll edit this, in my case in rails 3 it just pulled em from the whole table without filtering.
I have a table named acts, and I'll like to run a query that rolls up act values for a whole week. I'd like to make sure the query always returns one row for each day of the week, even if there are no records for that day. Right now I'm doing it like this:
def self.this_week_totals
sunday = Time.now.beginning_of_week(:sunday).strftime("%Y-%m-%d")
connection.select_values(<<-EOQ)
SELECT COALESCE(SUM(end_time - start_time), '0:00:00') AS total_time
FROM generate_series(0, 6) AS s(t)
LEFT JOIN acts
ON acts.day = '#{sunday}'::date + s.t
WHERE deleted_at IS NULL
GROUP BY s.t
ORDER BY s.t
EOQ
end
Is there any way I could make this a named scope on the Act class so it can be combined with other conditions, for example to filter the Acts by a client_id? Since acts isn't in my FROM, but is part of the LEFT JOIN, I'm guessing not, but perhaps someone out there knows a way.
Edit: Just to clarify, the goal is for this method to always return exactly 7 Act objects, regardless of what's in the database.
if you want your query object to be chainable it must be an ActiveRelation object
where, select, order and the other Arel objects return ActiveRelation objects that are chainable, so if the below works you can chain off of the returned query object
note in rails 3 and up having a class method that returns an ActiveRelation is basically the same as a scope, they are both chainable query objects
class Act
def self.this_week_totals
sunday = Time.now.beginning_of_week(:sunday).strftime("%Y-%m-%d")
select("COALESCE(SUM(end_time - start_time), '0:00:00') AS total_time")
.from("generate_series(0, 6) AS s(t)")
.joins("LEFT JOIN acts ON acts.day = '#{sunday}'::date + s.t")
.where("deleted_at IS NULL")
.group("s.t")
.order("s.t")
end
# ...
end
client_id = params[:client_id]
Act.this_week_totals.where("client_id = ?", client_id)
http://api.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-from
Although I really thought I could use the solution from #house9, I don't see any way to avoid compromising on at least one of these goals:
Always yield 7 Act objects.
Return an ActiveRelation so I can compose this method with other scopes.
Permit joining to the clients table.
Here is the part-SQL/part-Ruby solution I'm actually using, which sadly gives up on point #2 above and also returns tuples rather than Acts:
def self.this_week(wk=0)
sunday = Time.now.beginning_of_week(:sunday)
sunday += wk.weeks
not_deleted.where("day BETWEEN ? AND ?", sunday, sunday + 7.days)
end
scope :select_sum_total_hours,
select("EXTRACT(EPOCH FROM COALESCE(SUM(end_time - start_time), '0:00:00'))/3600 AS total_hours")
scope :select_sum_total_fees,
joins(:client).
select("SUM(COALESCE(clients.rate, 0) * EXTRACT(EPOCH FROM COALESCE(end_time - start_time, '0:00:00'))/3600) AS total_fees")
def self.this_week_totals_by_day(wk=0)
totals = Hash[
this_week(wk)
.select("EXTRACT(DAY FROM day) AS just_day")
.select_sum_total_hours
.select_sum_total_fees
.group("day")
.order("day")
.map{|act| [act.just_day, [act.total_hours.to_f, act.total_fees.to_money]]}
]
sunday = Time.now.beginning_of_week(:sunday)
sunday += wk.weeks
(0..6).map do |x|
totals[(sunday + x.days).strftime("%d")] || [0, 0.to_money]
end
end
That could be DRYed up a bit, and it would produce errors if there were ever a month with fewer than 7 days, but hopefully it shows what I'm doing. The scopes for this_week, select_sum_total_hours, and select_sum_total_fees are used elsewhere, so I want to pull them out into scopes rather than repeating them in several big raw SQL strings.
I have 2 tables, a PlayingField table and Bookings table, and I want to write a rails query that takes in query parameters Start_date, End_date and Number_of_players
Scenario:
I pass in Start_date, End_date and Number_of_players to a method and I want to Get all PlayingFields that are available (not booked) between the dates provided and that the field can accommodate the number of players wanted.
PlayingField has_many bookings
Booking belongs_to PlayingField
pseudo code:
#Fields = PlayingFields.where(bookings.end_date > start_date AND bookings.start_date > end_date AND PlayingFields.capacity >= number_of_players)
Can someone please tell me what the best way to do this is on the rails side of things?
How can I query the database through rails to get all available PlayingFields between them dates and for the number of players required?
Thanks
The rails would have to includ the bookings table before the SQL call.
PlayingFields.joins(:bookings).where(bookings.end_date > start_date AND bookings.start_date > end_date AND bookings.capacity >= number_of_players)
I'm also curious how those two objects programmatically relate. How does a Booking model become associated with a PlayingField ?
I have two models: ScheduledCourse and ScheduledSession.
scheduled_course has_many scheduled_sessions
scheduled_session belongs_to scheduled_course
ScheduledCourse has a virtual attribute...
def start_at
s = ScheduledSession.where("scheduled_course_id = ?", self.id).order("happening_at ASC").limit(1)
s[0].happening_at
end
... the start_at virtual attribute checks all the ScheduledSessions that belongs to the ScheduledCourse and it picks the earliest one. So start_at is the date when the first session happens.
Now I need to write in the controller so get only the records that start today and go into the future. Also I need to write another query that gets only past courses.
I can't do the following because start_at is a virtual attribute
#scheduled_courses = ScheduledCourse.where('start_at >= ?', Date.today).page(params[:page])
#scheduled_courses = ScheduledCourse.where('start_at <= ?', Date.today)
SQLite3::SQLException: no such column: start_at: SELECT "scheduled_courses".* FROM "scheduled_courses" WHERE (start_at >= '2012-03-13') LIMIT 25 OFFSET 0
You can't perform SQL queries on columns that aren't in the database. You should consider making this a real database column if you intend to do queries on it instead of a fake column; but if you want to select items from this collection, you can still do so. You just have to do it in Ruby.
ScheduledCourse.page(params).find_all {|s| s.start_at >= Date.today}
Veraticus is right; You cannot use virtual attributes in queries.
However, I think you could just do:
ScheduledCourse.joins(:scheduled_sessions).where('scheduled_courses.happening_at >= ?', Date.today)
It will join the tables together by matching ids, and then you can look at the 'happening_at' column, which is what your 'start_at' attribute really is.
Disclaimer: Untested, but should work.
I wonder if this would be solved by a subquery ( the subquery being to find the earliest date first). If so, perhaps the solution here might help point in a useful direction...