How to convert this into active records queries?
#test = #keyword_list.find_by_sql("
SELECT keywords.keyword, minimum_ranking.min_position from keywords
JOIN (select keyword_id, min(position) as min_position from rankings group by keyword_id) minimum_ranking
on minimum_ranking.keyword_id = keywords.id
where created_at between ('2019-10-15 07:00:00') AND ('#{date}')
")
Not only that before these code, i already have 2 layer of association
#project = Project.find(params[:id])
#keywords = #project.keywords
#pagy, #keyword_list = pagy(#keywords.includes(:rankings).order(current_ranking: :asc), items: 50)
At the moment i been running loop and .where on the views, which making loading the page extremely slow. i am trying to tackle this issue by making a single sql queries in the controller, managed to wrote it in sql but can't figure out to do it in Active Record.
Have a look at https://scuttle.io to get started:
Keyword.select(
[
Keyword.arel_table[:keyword], MinimumRanking.arel_table[:min_position]
]
).where(
Arel::Nodes::Between.new(
:created_at, (
Arel::Nodes::Group.new(LITERAL<'2019-10-15 07:00:00'>)
).and(Arel::Nodes::Group.new(LITERAL<'#{date}'>))
)
).joins(
Keyword.arel_table.join(Ranking.arel_table).on(
MinimumRanking.arel_table[:keyword_id].eq(Keyword.arel_table[:id])
).join_sources
)
Related
I am currently implementing Ransack for searching functionality.
I have a model Campaigns which collaborates campaigns that the user directly created as well as others so long as the user belongs to the same vendor.
I can combine the results as such:
#search = current_user.campaigns + current_user.vendor.campaigns.where.not(:user_id => current_user.id)
Problem with this is that Ransack will not accept this combination and spits out
no implicit conversion of Ransack::Search into Array
Can someone point me in the direction on how to refactor this code?
TIA
Adding Addition Data
When looking at my console I can see *current_user.campaigns*:
Campaign Load (0.3ms)
SELECT DISTINCT "campaigns".* FROM "campaigns"
WHERE "campaigns"."user_id" = ? [["user_id", 2]]
Running *current_user.vendor.campaigns* give me:
Campaign Load (0.4ms)
SELECT DISTINCT "campaigns".* FROM "campaigns"
INNER JOIN "weeks" ON "campaigns"."id" = "weeks"."campaign_id"
INNER JOIN "products" ON "weeks"."product_id" = "products"."id"
INNER JOIN "locations" ON "products"."location_id" = "locations"."id"
WHERE "locations"."vendor_id" = ? [["vendor_id", 2]]
I can get the first filter of current_user achieved with:
#search = Campaign.where("campaigns.user_id" => current_user.id).search(params[:q])
But I am lost of how I go about building the rest of the join tables to include both elements of data
Solved
#search = Campaign.includes(:weeks).where('(campaigns.user_id LIKE ?) OR (weeks.vendor_id LIKE ?)', current_user.id, current_user.vendor.id).search(params[:q])
I have 2 models - Restaurant and Feature. They are connected via has_and_belongs_to_many relationship. The gist of it is that you have restaurants with many features like delivery, pizza, sandwiches, salad bar, vegetarian option,… So now when the user wants to filter the restaurants and lets say he checks pizza and delivery, I want to display all the restaurants that have both features; pizza, delivery and maybe some more, but it HAS TO HAVE pizza AND delivery.
If I do a simple .where('features IN (?)', params[:features]) I (of course) get the restaurants that have either - so or pizza or delivery or both - which is not at all what I want.
My SQL/Rails knowledge is kinda limited since I'm new to this but I asked a friend and now I have this huuuge SQL that gets the job done:
Restaurant.find_by_sql(['SELECT restaurant_id FROM (
SELECT features_restaurants.*, ROW_NUMBER() OVER(PARTITION BY restaurants.id ORDER BY features.id) AS rn FROM restaurants
JOIN features_restaurants ON restaurants.id = features_restaurants.restaurant_id
JOIN features ON features_restaurants.feature_id = features.id
WHERE features.id in (?)
) t
WHERE rn = ?', params[:features], params[:features].count])
So my question is: is there a better - more Rails even - way of doing this? How would you do it?
Oh BTW I'm using Rails 4 on Heroku so it's a Postgres DB.
This is an example of a set-iwthin-sets query. I advocate solving these with group by and having, because this provides a general framework.
Here is how this works in your case:
select fr.restaurant_id
from features_restaurants fr join
features f
on fr.feature_id = f.feature_id
group by fr.restaurant_id
having sum(case when f.feature_name = 'pizza' then 1 else 0 end) > 0 and
sum(case when f.feature_name = 'delivery' then 1 else 0 end) > 0
Each condition in the having clause is counting for the presence of one of the features -- "pizza" and "delivery". If both features are present, then you get the restaurant_id.
How much data is in your features table? Is it just a table of ids and names?
If so, and you're willing to do a little denormalization, you can do this much more easily by encoding the features as a text array on restaurant.
With this scheme your queries boil down to
select * from restaurants where restaurants.features #> ARRAY['pizza', 'delivery']
If you want to maintain your features table because it contains useful data, you can store the array of feature ids on the restaurant and do a query like this:
select * from restaurants where restaurants.feature_ids #> ARRAY[5, 17]
If you don't know the ids up front, and want it all in one query, you should be able to do something along these lines:
select * from restaurants where restaurants.feature_ids #> (
select id from features where name in ('pizza', 'delivery')
) as matched_features
That last query might need some more consideration...
Anyways, I've actually got a pretty detailed article written up about Tagging in Postgres and ActiveRecord if you want some more details.
This is not "copy and paste" solution but if you consider following steps you will have fast working query.
index feature_name column (I'm assuming that column feature_id is indexed on both tables)
place each feature_name param in exists():
select fr.restaurant_id
from
features_restaurants fr
where
exists(select true from features f where fr.feature_id = f.feature_id and f.feature_name = 'pizza')
and
exists(select true from features f where fr.feature_id = f.feature_id and f.feature_name = 'delivery')
group by
fr.restaurant_id
Maybe you're looking at it backwards?
Maybe try merging the restaurants returned by each feature.
Simplified:
pizza_restaurants = Feature.find_by_name('pizza').restaurants
delivery_restaurants = Feature.find_by_name('delivery').restaurants
pizza_delivery_restaurants = pizza_restaurants & delivery_restaurants
Obviously, this is a single instance solution. But it illustrates the idea.
UPDATE
Here's a dynamic method to pull in all filters without writing SQL (i.e. the "Railsy" way)
def get_restaurants_by_feature_names(features)
# accepts an array of feature names
restaurants = Restaurant.all
features.each do |f|
feature_restaurants = Feature.find_by_name(f).restaurants
restaurants = feature_restaurants & restaurants
end
return restaurants
end
Since its an AND condition (the OR conditions get dicey with AREL). I reread your stated problem and ignoring the SQL. I think this is what you want.
# in Restaurant
has_many :features
# in Feature
has_many :restaurants
# this is a contrived example. you may be doing something like
# where(name: 'pizza'). I'm just making this condition up. You
# could also make this more DRY by just passing in the name if
# that's what you're doing.
def self.pizza
where(pizza: true)
end
def self.delivery
where(delivery: true)
end
# query
Restaurant.features.pizza.delivery
Basically you call the association with ".features" and then you use the self methods defined on features. Hopefully I didn't misunderstand the original problem.
Cheers!
Restaurant
.joins(:features)
.where(features: {name: ['pizza','delivery']})
.group(:id)
.having('count(features.name) = ?', 2)
This seems to work for me. I tried it with SQLite though.
The title is confusing, but allow me to explain. I have a Car model that has multiple datapoints with different timestamps. We are almost always concerned with attributes of its latest status. So the model has_many statuses, along with a has_one to easily access it's latest one:
class Car < ActiveRecord::Base
has_many :statuses, class_name: 'CarStatus', order: "timestamp DESC"
has_one :latest_status, class_name: 'CarStatus', order: "timestamp DESC"
delegate :location, :timestamp, to: 'latest_status', prefix: 'latest', allow_nil: true
# ...
end
To give you an idea of what the statuses hold:
loc = Car.first.latest_location # Location object (id = 1 for example)
loc.name # "Miami, FL"
Let's say I wanted to have a (chainable) scope to find all cars with a latest location id of 1. Currently I have a sort of complex method:
# car.rb
def self.by_location_id(id)
ids = []
find_each(include: :latest_status) do |car|
ids << car.id if car.latest_status.try(:location_id) == id.to_i
end
where("id in (?)", ids)
end
There may be a quicker way to do this using SQL, but not sure how to only get the latest status for each car. There may be many status records with a location_id of 1, but if that's not the latest location for its car, it should not be included.
To make it harder... let's add another level and be able to scope by location name. I have this method, preloading statuses along with their location objects to be able to access the name:
def by_location_name(loc)
ids = []
find_each(include: {latest_status: :location}) do |car|
ids << car.id if car.latest_location.try(:name) =~ /#{loc}/i
end
where("id in (?)", ids)
end
This will match the location above with "miami", "fl", "MIA", etc... Does anyone have any suggestions on how I can make this more succinct/efficient? Would it be better to define my associations differently? Or maybe it will take some SQL ninja skills, which I admittedly don't have.
Using Postgres 9.1 (hosted on Heroku cedar stack)
All right. Since you're using postgres 9.1 like I am, I'll take a shot at this. Tackling the first problem first (scope to filter by location of last status):
This solution takes advantage of PostGres's support for analytic functions, as described here: http://explainextended.com/2009/11/26/postgresql-selecting-records-holding-group-wise-maximum/
I think the following gives you part of what you need (replace/interpolate the location id you're interested in for the '?', naturally):
select *
from (
select cars.id as car_id, statuses.id as status_id, statuses.location_id, statuses.created_at, row_number() over (partition by statuses.id order by statuses.created_at) as rn
from cars join statuses on cars.id = statuses.car_id
) q
where rn = 1 and location_id = ?
This query will return car_id, status_id, location_id, and a timestamp (called created_at by default, although you could alias it if some other name is easier to work with).
Now to convince Rails to return results based on this. Because you'll probably want to use eager loading with this, find_by_sql is pretty much out. There is a trick I discovered though, using .joins to join to a subquery. Here's approximately what it might look like:
def self.by_location(loc)
joins(
self.escape_sql('join (
select *
from (
select cars.id as car_id, statuses.id as status_id, statuses.location_id, statuses.created_at, row_number() over (partition by statuses.id order by statuses.created_at) as rn
from cars join statuses on cars.id = statuses.car_id
) q
where rn = 1 and location_id = ?
) as subquery on subquery.car_id = cars.id order by subquery.created_at desc', loc)
)
end
Join will act as a filter, giving you only the Car objects that were involved in the subquery.
Note: In order to refer to escape_sql as I do above, you'll need to modify ActiveRecord::Base slightly. I do this by adding this to an initializer in the app (which I place in app/config/initializers/active_record.rb):
class ActiveRecord::Base
def self.escape_sql(clause, *rest)
self.send(:sanitize_sql_array, rest.empty? ? clause : ([clause] + rest))
end
end
This allows you to call .escape_sql on any of your models that are based on AR::B. I find this profoundly useful, but if you've got some other way to sanitize sql, feel free to use that instead.
For the second part of the question - unless there are multiple locations with the same name, I'd just do a Location.find_by_name to turn it into an id to pass into the above. Basically this:
def self.by_location_name(name)
loc = Location.find_by_name(name)
by_location(loc)
end
In my application I the next task that has not already been done by a user. I have Three models, A Book that has many Tasks and then I have a User that has has and belongs to many tasks. The table tasks_users table contains all completed tasks so I need to write a complex query to find the next task to perform.
I have came up with two solutions in pure SQL that works, but I cant translate them to rails, thats what I need help with
SELECT * FROM `tasks`
WHERE `tasks`.`book_id` = #book_id
AND `tasks`.`id` NOT IN (
SELECT `tasks_users`.`task_id`
FROM `tasks_users`
WHERE `tasks_users`.`user_id` = #user_id)
ORDER BY `task`.`date` ASC
LIMIT 1;
and equally without nested select
SELECT *
FROM tasks
LEFT JOIN tasks_users
ON tasks_users.tasks_id = task.id
AND tasks_users.user_id = #user_id
WHERE tasks_users.task_id IS NULL
AND tasks.book_id = #book_id
LIMIT 1;
This is what I Have done in rails with the MetaWhere plugin
book.tasks.joins(:users.outer).where(:users => {:id => nil})
but I cant figure out how to get the current user there too,
Thanks for any help!
I think this will duplicate the second form with the LEFT JOIN:
class Task < ActiveRecord::Base
scope :next_task, lambda { |book,user| book.tasks.\
joins("LEFT JOIN task_users ON task_users.task_id=tasks.id AND task_users.user_id=#{user.id}").\
where(:tasks=>{:task_users=>{:task_id=>nil}}).\
order("date DESC").limit(1) }
end
Note that instead of tasks_users this uses the table name task_user, which is more typical for a join model. Also, it needs to be called with:
Task.next_task(#book_id,#user_id)
book.tasks.where("tasks.id not in (select task_id from tasks_users where user_id=?)", #user_id).first
That would give you the first task that doesn't already have an entry in tasks_users for the current user.
I have a voting system with two models: Item(id, name) and Vote(id, item_id, user_id).
Here's the code I have so far:
class Item < ActiveRecord::Base
has_many :votes
def self.most_popular
items = Item.all #where can I optimize here?
items.sort {|x,y| x.votes.length <=> y.votes.length}.first #so I don't need to do anything here?
end
end
There's a few things wrong with this, mainly that I retrieve all the Item records, THEN use Ruby to compute popularity. I am almost certain there is a simple solution to this, but I can't quite put my finger on it.
I'd much rather gather records and run the calculations in the initial query. This way, I can add a simple :limit => 1 (or LIMIT 1) to the query.
Any help would be great--either rewrite in all ActiveRecord or even in raw SQl. The latter would actually give me a much clearer picture of the nature of the query I want to execute.
Group the votes by item id, order them by count and then take the item of the first one. In rails 3 the code for this is:
Vote.group(:item_id).order("count(*) DESC").first.item
In rails 2, this should work:
Vote.all(:order => "count(*) DESC", :group => :item_id).first.item
sepp2k has the right idea. In case you're not using Rails 3, the equivalent is:
Vote.first(:group => :item_id, :order => "count(*) DESC", :include => :item).item
Probably there's a better way to do this in ruby, but in SQL (mysql at least) you could try something like this to get a top 10 ranking:
SELECT i.id, i.name, COUNT( v.id ) AS total_votes
FROM Item i
LEFT JOIN Vote v ON ( i.id = v.item_id )
GROUP BY i.id
ORDER BY total_votes DESC
LIMIT 10
One easy way of handling this is to add a vote count field to the Item, and update that each time there is a vote. Rails used to do that automatically for you, but not sure if it's still the case in 2.x and 3.0. It's easy enough for you to do it in any case using an Observer pattern or else just by putting in a "after_save" in the Vote model.
Then your query is very easy, by simply adding a "VOTE_COUNT DESC" order to your query.