I use the gem rails3-jquery-autocomplete for the autocomplete searching of items in my database. The autocomplete is working fine, but I would need to add another condition to the generated query.
If I start to write a searched string, then is generated following query:
SELECT persons.id, persons.name FROM "persons" WHERE (LOWER(persons.name) ILIKE 'jo%') ORDER BY persons.name ASC LIMIT 10
This returns me all rows, where the name starts at jo.
But how could I search all persons, which name starts at jo and simultaneously, for example, the column active_person=1?
Is there any helper for this purpose or something like that?
Thank you
If I understood the context correctly, then active_person is a boolean that indicates whether the user is active or not.
If this behavior is desirable most of time - that you search for users/people that are only active then you could include a default_scope in your Person model like this:
class Person < ActiveRecord::Base
default_scope where(:active_person => 1)
end
This way any query that is ever generated will be also checking that active_person = 1
More on default scopes here: http://apidock.com/rails/ActiveRecord/Base/default_scope/class
I understand that #Andrei 's answer is correct, but its not what I was looking for. I guess its same for #user984621 too. What I was looking for is I want to add an extra condition to the query.
By reading this https://github.com/crowdint/rails3-jquery-autocomplete/blob/master/lib/rails3-jquery-autocomplete/orm/active_record.rb
I found that rails autocomplete supports additional conditions, you just have to pass another parameter to the default usage, like this
autocomplete :user, :name, :where => { :role => 'employee'}
instead of this
autocomplete :user, :name
Change WHERE (LOWER(persons.name) ILIKE 'jo%') to WHERE (LOWER(persons.name) ILIKE 'jo%') AND active_person = 1
You can chain together loads of clauses with ANDs and OR in that way.
Note that this is really a question about SQL: your title and tags are a bit misleading.
Related
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.
Let's say I've got User class with an :email field. And let's say I'm using activeadmin to manage Users.
Making a filter that returns emails that match one string, e.g. "smith", is very simple. In admin/user.rb, I just include the line
filter :email
This gives me a filter widget that does the job.
However, this filter doesn't let me search for the intersection of multiple terms. I can search for emails containing "smith", but not for emails containing both "smith" AND ".edu".
Google tells me that activerecord uses Ransack under the hood, and the Ransack demo has an 'advanced' mode that permits multiple term searches.
What's the easiest way to get a multiple term search widget into activeadmin?
Ideally, I'd like a widget that would allow me to enter smith .edu or smith AND .edu to filter for emails containing both terms.
there is simple solution using ranasckable scopes
So put something like this in your model
class User < ActiveRecord::Base
....
scope :email_includes, ->(search) {
current_scope = self
search.split.uniq.each do |word|
current_scope = current_scope.where('user.email ILIKE ?', "%#{word}%")
end
current_scope
}
def self.ransackable_scopes(auth_object = nil)
[ :email_includes]
end
end
After this you can add filter with AA DSL
Like
filter :email_includes, as: :string, label: "Email"
UPD
should work if change email_contains_any to email_includes
I've figured out a solution but it's not pretty.
The good news is that Ransack has no trouble with multiple terms searches. These searches use the 'predicate' cont_all. The following line works for finding emails containing 'smith' and '.edu'.
User.ransack(email_cont_all: ['smith','.edu'] ).result
Since these searches are easy in Ransack, they're probably straightforward in Activeadmin, right? Wrong! To get them working, I needed to do three things.
I put a custom ransack method (a.k.a. ransacker) into User.rb. I named the ransacker email_multiple_terms.
class User < ActiveRecord::Base
# ...
ransacker :email_multiple_terms do |parent|
parent.table[:path]
end
I declared a filter in my activeadmin dashboard, and associated it with the ransacker. Note that the search predicate cont_all is appended to the ransacker name.
admin/User.rb:
ActiveAdmin.register User do
# ...
filter :email_multiple_terms_cont_all, label: "Email", as: :string
This line creates the filter widget in Activeadmin. We're nearly there. One problem left: Activeadmin sends search queries to ransack as a single string (e.g. "smith .edu"), whereas our ransacker wants the search terms as an array. Somewhere, we need to convert the single string into an array of search terms.
I modified activeadmin to split the search string under certain conditions. The logic is in a method that I added to lib/active_admin/resource_controller/data_access.rb.
def split_search_params(params)
params.keys.each do |key|
if key.ends_with? "_any" or key.ends_with? "_all"
params[key] = params[key].split # turn into array
end
end
params
end
I then called this method inside apply_filtering.
def apply_filtering(chain)
#search = chain.ransack split_search_params clean_search_params params[:q]
#search.result
end
This code is live in my own fork of activeadmin, here: https://github.com/d-H-/activeadmin
So, to get multiple term search working, follow steps 1 and 2 above, and include my fork of A.A. in your Gemfile:
gem 'activeadmin', :git => 'git://github.com/d-H-/activeadmin.git'
HTH.
If anyone's got a simpler method, please share!
Just add three filters to your model:
filter :email_cont
filter :email_start
filter :email_end
It gives you a flexible way to manage your search.
This filter executes next sql code:
SELECT "admin_users".* FROM "admin_users"
WHERE ("admin_users"."email" ILIKE '%smith%' AND
"admin_users"."email" ILIKE '%\.edu')
ORDER BY "admin_users"."id" desc LIMIT 30 OFFSET 0
I expect that exactly what you're looking for.
I'm trying to figure out the count of certain types of articles. I have a very inefficient query:
Article.where(status: 'Finished').select{|x| x.tags & Article::EXPERT_TAGS}.size
In my quest to be a better programmer, I'm wondering how to make this a faster query. tags is an array of strings in Article, and Article::EXPERT_TAGS is another array of strings. I want to find the intersection of the arrays, and get the resulting record count.
EDIT: Article::EXPERT_TAGS and article.tags are defined as Mongo arrays. These arrays hold strings, and I believe they are serialized strings. For example: Article.first.tags = ["Guest Writer", "News Article", "Press Release"]. Unfortunately this is not set up properly as a separate table of Tags.
2nd EDIT: I'm using MongoDB, so actually it is using a MongoWrapper like MongoMapper or mongoid, not ActiveRecord. This is an error on my part, sorry! Because of this error, it screws up the analysis of this question. Thanks PinnyM for pointing out the error!
Since you are using MongoDB, you could also consider a MongoDB-specific solution (aggregation framework) for the array intersection, so that you could get the database to do all the work before fetching the final result.
See this SO thread How to check if an array field is a part of another array in MongoDB?
Assuming that the entire tags list is stored in a single database field and that you want to keep it that way, I don't see much scope of improvement, since you need to get all the data into Ruby for processing.
However, there is one problem with your database query
Article.where(status: 'Finished')
# This translates into the following query
SELECT * FROM articles WHERE status = 'Finished'
Essentially, you are fetching all the columns whereas you only need the tags column for your process. So, you can use pluck like this:
Article.where(status: 'Finished').pluck(:tags)
# This translates into the following query
SELECT tags FROM articles WHERE status = 'Finished'
I answered a question regarding general intersection like queries in ActiveRecord here.
Extracted below:
The following is a general approach I use for constructing intersection like queries in ActiveRecord:
class Service < ActiveRecord::Base
belongs_to :person
def self.with_types(*types)
where(service_type: types)
end
end
class City < ActiveRecord::Base
has_and_belongs_to_many :services
has_many :people, inverse_of: :city
end
class Person < ActiveRecord::Base
belongs_to :city, inverse_of: :people
def self.with_cities(cities)
where(city_id: cities)
end
# intersection like query
def self.with_all_service_types(*types)
types.map { |t|
joins(:services).merge(Service.with_types t).select(:id)
}.reduce(scoped) { |scope, subquery|
scope.where(id: subquery)
}
end
end
Person.with_all_service_types(1, 2)
Person.with_all_service_types(1, 2).with_cities(City.where(name: 'Gold Coast'))
It will generate SQL of the form:
SELECT "people".*
FROM "people"
WHERE "people"."id" in (SELECT "people"."id" FROM ...)
AND "people"."id" in (SELECT ...)
AND ...
You can create as many subqueries as required with the above approach based on any conditions/joins etc so long as each subquery returns the id of a matching person in its result set.
Each subquery result set will be AND'ed together thus restricting the matching set to the intersection of all of the subqueries.
I'm working on a Rails 3.2 app that uses Datamapper as its ORM. I'm looking for a way to sort a result set by an attribute of the associated model. Specifically I have the following models:
class Vehicle
include DataMapper::Resource
belongs_to :user
end
class User
include DataMapper::Resource
has n, :vehicles
end
Now I want to be able to query the vehicles and sort them by the name of the driver. I tried the following but neither seems to work with Datamapper:
> Vehicle.all( :order => 'users.name' )
ArgumentError: +options[:order]+ entry "users.name" does not map to a property in Vehicle
> Vehicle.all( :order => { :users => 'name' } )
ArgumentError: +options[:order]+ entry [:users, "name"] of an unsupported object Array
Right now I'm using Ruby to sort the result set post-query but obviously that's not helping performance any, also it stops me from further chaining on other scopes.
I spent some more time digging around and finally turned up an old blog which has a solution to this problem. It involves manually building the ordering query in DataMapper.
From: http://rhnh.net/2010/12/01/ordering-by-a-field-in-a-join-model-with-datamapper
def self.ordered_by_vehicle_name direction = :asc
order = DataMapper::Query::Direction.new(vehicle.name, direction)
query = all.query
query.instance_variable_set("#order", [order])
query.instance_variable_set("#links", [relationships['vehicle'].inverse])
all(query)
end
This will let you order by association and still chain on other scopes, e.g.:
User.ordered_by_vehicle_name(:desc).all( :name => 'foo' )
It's a bit hacky but it does what I wanted it to do at least ;)
Note: I'm not familiar with DataMapper and my answer might not be within the standards and recommendations of using DataMapper, but it should hopefully give you the result you're looking for.
I've been looking through various Google searches and the DataMapper documentation and I haven't found a way to "order by assocation attribute". The only solution I have thought of is "raw" SQL.
The query would look like this.
SELECT vehicles.* FROM vehicles
LEFT JOIN users ON vehicles.user_id = users.id
ORDER BY users.name
Unfortunately, from my understanding, when you directly query the database you won't get the Vehicle object, but the data from the database.
From the documentation: http://datamapper.org/docs/find.html. It's near the bottom titled "Talking directly to your data-store"
Note that this will not return Zoo objects, rather the raw data straight from the database
Vehicle.joins(:user).order('users.name').all
or in Rails 2.3,
Vehicle.all(:joins => "inner join users on vehicles.user_id = user.id", :order => 'users.name')
How do I define a model attribute as an expression of another attribute?
Example:
Class Home < ActiveRecord::Base
attr_accessible :address, :phone_number
Now I want to be able to return an attribute like :area_code, which would be an sql expression like "substr(phone_number, 1,3)".
I also want to be able to use the expression / attribute in a group by query for a report.
This seems to perform the query, but does not return an object with named attributes, so how do I use it in a view?
Rails Console:
#ac = Home.group("substr(phone_number, 1,3)").count
=> #<OrderedHash {"307"=>3, "515"=>1}>
I also expected this to work, but not sure what kind of object it is returning:
#test = Home.select("substr(phone_number, 1,3) as area_code, count(*) as c").group("substr(phone_number, 1,3)")
=> [#<Home>, #<Home>]
To expand on the last example. Here it is with Active Record logging turned on:
>Home.select("substr(phone_number, 1,3) as area_code, count(*) as c").group("substr(phone_number, 1,3)")
Output:
Home Load (0.3ms) SELECT substr(phone_number, 1,3) as area_code, count(*) as c FROM "homes" GROUP BY substr(phone_number, 1,3)
=> [#<Home>, #<Home>]
So it is executing the query I want, but giving me an unexpected data object. Shouldn't I get something like this?
[ #<area_code: "307", c: 3>, #<area_code: "515", c: 1> ]
you cannot access to substr(...) because it is not an attribute of the initialized record object.
See : http://guides.rubyonrails.org/active_record_querying.html "selecting specific fields"
you can workaround this this way :
#test = Home.select("substr(phone_number, 1,3) as phone_number").group(:phone_number)
... but some might find it a bit hackish. Moreover, when you use select, the records will be read-only, so be careful.
if you need the count, just add .count at the end of the chain, but you will get a hash as you already had. But isn't that all you need ? what is your purpose ?
You can also use an area_code column that will be filled using callbacks on create and update, so you can index this column ; your query will run fast on read, though it will be slower on insertion.