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View Code? Open in Web Editor NEWfix n+1 aggregate sql functions for rails
License: MIT License
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distinct values?
Let's say I have Departments and Employees, and every employee has an employee_type "temporary", "permanent", "retired", I dunno.
I wanna fetch a list of Departments and for each one have an attribute with an array of distinct employee_types found in that Department's employees.
I could hack out the proper GROUP BY query to get these (although I haven't yet). Using postgres-specific functions maybe even get the multiple unique/distinct values in a single SQL result row, as a pg array or something. Although I don't know if I'd need to do that if I was just writing it out manual.
Is there any hope of getting eager_group flexible enough to let me write this and have it magically done and have the array assigned to a model attributes?
has_many :through , aggregate_function count result incorrect when middle table has duplicate association record.
In eager_group_spec.rb
if I change data.
student4 = Student.create name: 'Student 4'
teacher1.students = [student1]
teacher2.students = [student2, student2, student3, student4]
Then teacher1.students_count result will be 4.
The students_count does not count by distinct records.
aggregate_function count return nil when no record on has many association
If I add post3 in data.rb
post1 = Post.create(title: "First post!")
post2 = Post.create(title: "Second post!")
post3 = Post.create(title: "Third post!")
post1.comments.create(status: 'created', rating: 4)
post1.comments.create(status: 'approved', rating: 5)
post1.comments.create(status: 'deleted', rating: 0)
post2.comments.create(status: 'approved', rating: 3)
post2.comments.create(status: 'approved', rating: 5)
eager_group_spec.rb
it 'gets both Post#approved_comments_count and Post#comments_average_rating' do
posts = Post.all.eager_group(:approved_comments_count, :comments_average_rating)
expect(posts[0].approved_comments_count).to eq 1
expect(posts[0].comments_average_rating).to eq 3
expect(posts[1].approved_comments_count).to eq 2
expect(posts[1].comments_average_rating).to eq 4
expect(posts[2].approved_comments_count).to eq 0
end
Result:
Failure/Error: expect(posts[2].approved_comments_count).to eq 0
expected: 0
got: nil
problem when FK is not an integer id
I have an association where I use a text string for my primary key.
has_many :children, class_name: "ActsAsTaggableOn::Tag", foreign_key: :parent_name, primary_key: :name, dependent: :nullify
define_eager_group :children_count, :children, :count, :*
when I do eager_group count, it is associating with the object's id instead of the association's PK (:name)
irb(main):016:0> tag = ActsAsTaggableOn::Tag.find_by(name: "Africa")
irb(main):017:0> tag.children.count
ActsAsTaggableOn::Tag Count (0.5ms) SELECT COUNT(*) FROM "aat_tags" WHERE "aat_tags"."parent_name" = $1 [["parent_name", "Africa"]]
=> 60
irb(main):018:0> tag.children_count
ActsAsTaggableOn::Tag Count (1.2ms) SELECT COUNT(*) AS "count_all", "aat_tags"."parent_name" AS "aat_tags_parent_name" FROM "aat_tags" WHERE "aat_tags"."parent_name" = $1 GROUP BY "aat_tags"."parent_name" [["parent_name", "3018"]]
=> 0
irb(main):019:0> tag.id
=> 3018
support many to many associations
primary_key mismatch with sum in MySQL
I found a issue with MySQL (or MariaDB in my case) and using sum aggregation.
The Primary keys on the DB query seem to be returned with string primary_keys. Which then does not match the primary_key of the given record for mapping the values.
As the tests only run against sqlite this issue does not seem present. But i thought it might be interesting for someone else.
My change can be seen here: https://github.com/maxigs/eager_group/blob/master/lib/eager_group/preloader.rb#L48
(I just copied the whole class into an initializer in my rails project for now, so i could test it with real database)
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