So I have a array of records and I would like to group by 2 levels
Essentially I would like to group_by{|x| x.field1 } and then each value in hash to be further grouped in by field2. Effectively leading to a tree that I can dump out.
def treemaker(array = [])
tree = ledgers.group_by{|x|x.master_group}
tree.each{|x,z| tree[x] = z.group_by{|y| y.account_group}}
tree
end
I would then render tree in a way that i can be put into a "tree" javascript plugin.
Is there a more efficient way?
Sample Input: An Array of ActiveRecord objects, where the model contains, fields master_group, account_group and name
Class MyModel < ActiveRecord::Base
validates :master_group, :account_group, :name, :presence => true
end
Sample Ouput:
{"master_group1" => {"account_group1" => ["name1","name2",...],
"account_groupx" => ["name3", "name4",...],
....},
"master_group2" => {"account_group2" => ["namex", "namey"]},
...
}
I'm not specifically looking for an "SQL grouping" solution (but that would be nice too). Just a solution using enumerables on a any given list of ruby objects.
#xaxxon sent me thinking in the right way basically with the "default value of hash" path.
I think i can now add a method to my model where i can use all sorts of scopes and tack on tree at the end to get my models in tree mode.
class MyModel < ActiveRecord::Base
validates :master_group, :account_group, :name, :presence => true
def self.tree(field1 = 'master_group', field2 = 'account_group')
tree = Hash.new{|hash,key| hash[key] = Hash.new{|h,k| h[k] = []}}
all.each do |item|
tree[item.send('field1')][item.send('field2')].push(item)
end
tree # bob's your uncle!
end
end
MyModel.recent.tree => Hash of Hash of arrays
set up some fake data
foo=[{:a=>1,:b=>2},{:a=>3,:b=>4}]
set up the output data structure
tree={}
populate the output data structure - this is weird looking because you have to populate the hashes that don't exist when they don't exist, hence the ||={} stuff.
foo.each{|thing| (tree[thing[:a]]||={})[thing[:b]]=thing}
looks good.. :a is your master group and :b is your account_group
pp tree
{1=>{2=>{:a=>1, :b=>2}}, 3=>{4=>{:a=>3, :b=>4}}}
Related
I’m using Rails 4.2.7. I have an attribute in my model that doesn’t have a database field underneath it
attr_accessor :division
This gets initialized when I create a new object.
my_object = MyObject.new(:name => name,
:age => get_age(data_hash),
:overall_rank => overall_rank,
:city => city,
:state => state,
:country => country,
:age_group_rank => age_group_rank,
:gender_rank => gender_rank,
:division => division)
What I would like is when this field gets set (if it is not nil), for two other fields that do have mappings in the database to get set. The other fields would be substrings of the “division” field. Where do I put that logic?
I'd probably drop the attr_accessor :division and do it by hand with:
def division=(d)
# Break up `d` as needed and assign the parts to the
# desired real attributes.
end
def division
# Combine the broken out attributes as needed and
# return the combined string.
end
With those two methods in place, the following will all call division=:
MyObject.new(:division => '...')
MyObject.create(:division => '...')
o = MyObject.find(...); o.update(:division => '...')
o = MyObject.find(...); o.division = '...'
so the division and the broken out attributes will always agree with each other.
If you try to use one of the lifecycle hooks (such as after_initialize) then things can get out of sync. Suppose division has the form 'a.b' and the broken out attributes are a and b and suppose that you're using one of the ActiveRecord hooks to break up division. Then saying:
o.division = 'x.y'
should give you o.a == 'x' but it won't because the hook won't have executed yet. Similarly, if you start with o.division == 'a.b' then
o.a = 'x'
won't give you o.division == 'x.b' so the attributes will have fallen out of sync again.
I see couple of options here
You can add it in your controller as follows
def create
if params[:example][:division]
# Set those params here
end
end
Or you can use before_save In your model
before_save :do_something
def do_something
if division
# Here!
end
end
I have two models :
class Project < ActiveRecord::Base
has_many :ticket
attr_accessible ....
end
class Ticket < ActiveRecord::Base
belongs_to :project
attr_accessible done_date, description, ....
end
In my ProjectsController I would like to create a two dimensional hash to get in one variable for one project all tickets that are done (with done_date as key and description as value).
For example i would like a hash like this :
What i'm looking for :
#tickets_of_project = ["done_date_1" => ["a", "b", "c"], "done_date_2" => ["d", "e"]]
And what i'm currently trying (in ProjectsController) ...
def show
# Get current project
#project = Project.find(params[:id])
# Get all dones tickets for a project, order by done_date
#tickets = Ticket.where(:project_id => params[:id]).where("done_date IS NOT NULL").order(:done_date)
# Create a new hash
#tickets_of_project = Hash.new {}
# Make a loop on all tickets, and want to complete my hash
#tickets.each do |ticket|
# TO DO
#HOW TO PUT ticket.value IN "tickets_of_project" WITH KEY = ticket.done_date ??**
end
end
I don't know if i'm in a right way or not (maybe use .map instead of make a where query), but how can I complete and put values in hash by checking index if already exist or not ?
Thanx :)
I needed to do the same task before, following solution isn't pretty but should do it:
Ticket.where(:project_id => params[:id]).where("done_date IS NOT NULL").group_by {|t| t.done_date}.map {|k,v| [k => v.map {|vv| vv.value}] }.flatten.first
Rails 4, Mongoid instead of ActiveRecord (but this should change anything for the sake of the question).
Let's say I have a MyModel domain class with some validation rules:
class MyModel
include Mongoid::Document
field :text, type: String
field :type, type: String
belongs_to :parent
validates :text, presence: true
validates :type, inclusion: %w(A B C)
validates_uniqueness_of :text, scope: :parent # important validation rule for the purpose of the question
end
where Parent is another domain class:
class Parent
include Mongoid::Document
field :name, type: String
has_many my_models
end
Also I have the related tables in the database populated with some valid data.
Now, I want to import some data from an CSV file, which can conflict with the existing data in the database. The easy thing to do is to create an instance of MyModel for every row in the CSV and verify if it's valid, then save it to the database (or discard it).
Something like this:
csv_rows.each |data| # simplified
my_model = MyModel.new(data) # data is the hash with the values taken from the CSV row
if my_model.valid?
my_model.save validate: false
else
# do something useful, but not interesting for the question's purpose
# just know that I need to separate validation from saving
end
end
Now, this works pretty smoothly for a limited amount of data. But when the CSV contains hundreds of thousands of rows, this gets quite slow, because (worst case) there's a write operation for every row.
What I'd like to do, is to store the list of valid items and save them all at the end of the file parsing process. So, nothing complicated:
valids = []
csv_rows.each |data|
my_model = MyModel.new(data)
if my_model.valid? # THE INTERESTING LINE this "if" checks only against the database, what happens if it conflicts with some other my_models not saved yet?
valids << my_model
else
# ...
end
end
if valids.size > 0
# bulk insert of all data
end
That would be perfect, if I could be sure that the data in the CSV does not contain duplicated rows or data that goes against the validation rules of MyModel.
My question is: how can I check each row against the database AND the valids array, without having to repeat the validation rules defined into MyModel (avoiding to have them duplicated)?
Is there a different (more efficient) approach I'm not considering?
What you can do is validate as model, save the attributes in a hash, pushed to the valids array, then do a bulk insert of the values usint mongodb's insert:
valids = []
csv_rows.each |data|
my_model = MyModel.new(data)
if my_model.valid?
valids << my_model.attributes
end
end
MyModel.collection.insert(valids, continue_on_error: true)
This won't however prevent NEW duplicates... for that you could do something like the following, using a hash and compound key:
valids = {}
csv_rows.each |data|
my_model = MyModel.new(data)
if my_model.valid?
valids["#{my_model.text}_#{my_model.parent}"] = my_model.as_document
end
end
Then either of the following will work, DB Agnostic:
MyModel.create(valids.values)
Or MongoDB'ish:
MyModel.collection.insert(valids.values, continue_on_error: true)
OR EVEN BETTER
Ensure you have a uniq index on the collection:
class MyModel
...
index({ text: 1, parent: 1 }, { unique: true, dropDups: true })
...
end
Then Just do the following:
MyModel.collection.insert(csv_rows, continue_on_error: true)
http://api.mongodb.org/ruby/current/Mongo/Collection.html#insert-instance_method
http://mongoid.org/en/mongoid/docs/indexing.html
TIP: I recommend if you anticipate thousands of rows to do this in batches of 500 or so.
I have a place object that has the following parameters: phone, category, street, zip, website.
I also have an array of place objects: [place1, place2, place3, place4, place5].
What's the best way to sort the array of places, based on the parameter availability? I.e., if place1 has the most available parameters, or the least number of parameters that are nil, it should be reordered to first and so on.
Edit: These objects are not ActiveRecord objects
I'd let each Place object know how complete it was:
class Place
attr_accessor :phone, :category, :street, :website, :zip
def completeness
attributes.count{|_,value| value.present?}
end
end
Then it is easy to sort your place objects by completeness:
places.sort_by(&:completeness)
Edit: Non-ActiveRecord solution:
I had assumed this was an ActiveRecord model because of the Ruby on Rails tag. Since this is a non-ActiveRecord model, you can use instance_variables instead of attributes. (By the way, congratulations for knowing that domain models in Rails don't have to inherit from ActiveRecord)
class Place
attr_accessor :phone, :category, :street, :website, :zip
def completeness
instance_variables.count{|v| instance_variable_get(v).present?}
end
end
Edit 2: Weighted attributes
You have a comment about calculating a weighted score. In this case, or when you want to choose specific attributes, you can put the following in your model:
ATTR_WEIGHTS = {phone:1, category:1, street:2, website:1, zip:2}
def completeness
ATTR_WEIGHTS.select{|k,v| instance_variable_get(k).present?}.sum(&:last)
end
Note that the sum(&:last) is equivalent to sum{|k,v| v} which in turn is a railsism for reduce(0){|sum, (k,v)| sum += v}.
I'm sure there's a better way to do it, but this is a start :
ruby fat one liner
values = {phone: 5, category: 3, street: 5, website: 3, zip: 5} #Edit these values to ponderate.
array = [place1, place2, place3, place4, place5]
sorted_array = array.sort_by{ |b| b.attributes.select{ |k, v| values.keys.include?(k.to_sym) && v.present? }.inject(0){ |sum, n| sum + values[n[0]] } }.reverse
So we're basically creating a sub-hash of the attributes of your ActiveRecord object by only picking the key-value pairs that are in the values hash and only if they have a present? value.
Then on this sub-hash, we're invoking inject that will sum the ponderated values we've put in the values hash. Finally, we reverse everything so you have the highest score first.
To make it clean, I suggest you implement a method that will compute the score of each object in an instance method in your model, like mark suggested
If you have a class Place:
class Place
attr_accessor :phone, :category, :street, :website, :zip
end
and you create an instance place1:
place1 = Place.new
place1.instance_variables # => []
place1.instance_variables.size # => 0
place1.phone = '555-1212' # => "555-1212"
place1.instance_variables # => [ :#phone ]
place1.instance_variables.size # => 1
And create the next instance:
place2 = Place.new
place2.phone = '555-1212'
place2.zip = '00000'
place2.instance_variables # => [ :#phone, :#zip ]
place2.instance_variables.size # => 2
You can sort by an ascending number of instance variables that have been set:
[place1, place2].sort_by{ |p| p.instance_variables.size }
# => [ #<Place:0x007fa8a32b51a8 #phone="555-1212">, #<Place:0x007fa8a31f5380 #phone="555-1212", #zip="00000"> ]
Or sort in descending order:
[place1, place2].sort_by{ |p| p.instance_variables.size }.reverse
# => [ #<Place:0x007fa8a31f5380 #phone="555-1212", #zip="00000">, #<Place:0x007fa8a32b51a8 #phone="555-1212"> ]
This uses basic Ruby objects, Rails is not needed, and it asks the object instances themselves what is set, so you don't have to maintain any external lists of attributes.
Note: this breaks if you set an instance variable to something, then set it back to nil.
This fixes it:
[place1,place2].sort_by{ |p|
p.instance_variables.reject{ |v|
p.instance_variable_get(v).nil?
}.size
}.reverse
and this shortens it by using Enumerable's count with a block:
[place1,place2].sort_by{ |p|
p.instance_variables.count{ |v|
!p.instance_variable_get(v).nil?
}
}.reverse
Let's say I have two objects: User and Race.
class User
attr_accessor :first_name
attr_accessor :last_name
end
class Race
attr_accessor :course
attr_accessor :start_time
attr_accessor :end_time
end
Now let's say I create an array of hashes like this:
user_races = races.map{ |race| {:user => race.user, :race => race} }
How do I then convert user_races into an array of structs, keeping in mind that I want to be able to access the attributes of both user and race from the struct element? (The key thing is I want to create a new object via Struct so that I can access the combined attributes of User and Race. For example, UserRace.name, UserRace.start_time.)
Try this:
class User
attr_accessor :first_name
attr_accessor :last_name
end
class Race
attr_accessor :course
attr_accessor :start_time
attr_accessor :end_time
end
UserRace = Struct.new(:first_name, :last_name, :course, :start_time, :end_time)
def get_user_race_info
user_races = races.map do |r|
UserRace.new(r.user.first_name, r.user.last_name,
r.course, r.start_time, r.end_time)
end
end
Now let's test the result:
user_races = get_user_race_info
user_races[0].first_name
user_races[0].end_time
Create a definition for the UserRace object (as a Struct), then just make an array of said objects.
UserRace = Struct.new(:user, :race)
user_races = races.map { |race| UserRace.new(race.user, race) }
# ...
user_races.each do |user_race|
puts user_race.user
puts user_race.race
end
if your hash has so many attributes such that listing them all:
user_races = races.map{ |race| {:user => race.user, :race => race, :best_lap_time => 552.33, :total_race_time => 1586.11, :ambient_temperature => 26.3, :winning_position => 2, :number_of_competitors => 8, :price_of_tea_in_china => 0.38 } } # garbage to show a user_race hash with many attributes
becomes cumbersome (or if you may be adding more attributes later), you can use the * ("splat") operator.
the splat operator converts an array into an argument list.
so you can populate Struct.new's argument list with the list of keys in your hash by doing:
UserRace = Struct.new(*races.first.keys)
of course, this assumes all hashes in your array have the same keys (in the same order).
once you have your struct defined, you can use inject to build the final array of objects. (inject greatly simplifies converting many objects from one data type to another.)
user_races.inject([]) { |result, user_race| result << UserRace.new(*user_race.values) }
You have this :::
user_races = races.map{ |race| {:user => race.user, :race => race} }
Now create a Struct as shown below :
UserRace = Struct.new(:user, :race)
And then ::
user_races.each do |user_race|
new_array << UserRace.new(user_race[:user],user_race[:race])
end
Haven't tested the code... should be fine... what say?
EDIT: Here I am adding the objects of UserRace to a new_array.