I have a function:
tracks.group_by { |t| t[:track].track_category }
Which creates a hash:
{
#<TrackCategory id: 2, order: 0> =>
[{:track =>
#<Track promo_order: 2>,
:order => 2},
{:track =>
#<Track promo_order: 2>,
:order => 1}],
#<TrackCategory id: 1, order: 1> =>
[{:track =>
#<Track promo_order: 2>,
:order => 2},
{:track =>
#<Track promo_order: 2>,
:order => 1}]
}
I've been trying to sort the TrackCategories by order, and inside that sort the Tracks by promo_order.
This keeps giving me errors, and I'm positive I'm doing something wrong
tracks.group_by { |t| t[:track].track_category }.sort_by { |t| t[:order] }.sort_by { |t| t[:promo_order] }
You are passing a key-value pair which came from group_by and was coerced as an array to sort_by, and then trying to access a key in the array, which of course doesn't exist.
In other words, you're mistaking the input used in sort_by. In the first sort_by, |t| is a hash key-pair generated by group_by and coerced into a array of the form [k,v]. In your case, t is:
[ #<TrackCategory id: 2, order: 0>,
[{:track =>
#<Track promo_order: 2>,
:order => 2},
{:track =>
#<Track promo_order: 2>,
:order => 1}],
#...
]
So what you want is to decompose the array in its elements so you can get the ones you want, something like:
tracks.group_by { |t| t[:track].track_category }
.sort_by { |t, _| t[:order] } # here you're sorting by TrackCategory#[:order]
And something similar on the second line, but using [:promo_order] instead.
Related
I have a huge array full of a bunch of hashes. What I need to do is single out one index hash from the array that meets a specific criteria. (doing this due to an rspec test, but having trouble singling out one of them)
My array is like this
[
{
"name" => "jon doe",
"team" => "team2",
"price" => 2000,
"eligibility_settings" => {}
},
{
"name" => "jonny doe",
"team" => "team1",
"value" => 2000,
"eligibility_settings" => {
"player_gender" => male,
"player_max_age" => 26,
"player_min_age" => 23,
"established_union_only" => true
}
},
{
"name" => "jonni doe",
"team" => "team3",
"price" => 2000,
"eligibility_settings" => {}
},
]
I need to single out the second one, based on its eligibility settings. I just took three of them from my array, have lots more, so simple active record methods like (hash.second) won't work in this instance.
I've tried things like
players.team.map(&:hash).find{ |x| x[ 'eligibility_settings?' ] == true}
However when I try this, I get a nil response. (which is odd)
I've also looked into using the ruby detect method, which hasn't gotten me anywhere either
Players.team.map(&:hash).['hash.seligibiltiy_settings'].detect { true }
Would anybody have any idea what to do with this one?
Notes
players.team.map(&:hash).find{ |x| x[ 'eligibility_settings?' ] == true}
Players.team.map(&:hash).['hash.seligibiltiy_settings'].detect { true }
Is is players or Players ?
Why is it plural?
If you can call map on team, it probably should be plural
Why do you convert to a hash?
eligibility_settings? isn't a key in your hash. eligibility_settings is
eligibility_settings can be a hash, but it cannot be true
If you want to check if it isn't empty, use !h['eligibility_settings'].empty?
Possible solution
You could use :
data = [
{
'name' => 'jon doe',
'team' => 'team2',
'price' => 2000,
'eligibility_settings' => {}
},
{
'name' => 'jonny doe',
'team' => 'team1',
'value' => 2000,
'eligibility_settings' => {
'player_gender' => 'male',
'player_max_age' => 26,
'player_min_age' => 23,
'established_union_only' => true
}
},
{
'name' => 'jonni doe',
'team' => 'team3',
'price' => 2000,
'eligibility_settings' => {}
}
]
p data.find { |h| !h['eligibility_settings'].empty? }
# {"name"=>"jonny doe", "team"=>"team1", "value"=>2000, "eligibility_settings"=>{"player_gender"=>"male", "player_max_age"=>26, "player_min_age"=>23, "established_union_only"=>true}}
If h['eligibility_settings'] can be nil, you can use :
data.find { |h| !h['eligibility_settings'].blank? }
or
data.find { |h| h['eligibility_settings'].present? }
I have data like this:
hash_data = [
{:key1 => 'value4', :sortby => 4},
{:key1 => 'valuesds6', :sortby => 6},
{:key1 => 'valuedsd', :sortby => 1},
{:key1 => 'value2_data_is_here', :sortby => 2}
]
I want to sort it to this by the key sortby
hash_data = [
{:key1 => 'valuedsd', :sortby => 1},
{:key1 => 'value2_data_is_here', :sortby => 2},
{:key1 => 'value4', :sortby => 4},
{:key1 => 'valuesds6', :sortby => 6}
]
I have tried using bubble sort, but is there any inbuilt function in a Hash class for such purposes?
Enumerable#sort_by to the rescue:
hash_data.sort_by { |hash| hash[:sortby] }
#=> [{:key1=>"valuedsd", :sortby=>1}, {:key1=>"value2_data_is_here", :sortby=>2}, {:key1=>"value4", :sortby=>4}, {:key1=>"valuesds6", :sortby=>6}]
If you don't care about initial object, I would suggest using Array#sort_by! to modify inplace - it is more resource-efficient:
hash_data.sort_by! { |hash| hash[:sortby] }
If you have different types of data as values to sortby key, you should first unify the data type and only then perform sorting.
To have array sorted in descending order, use Enumerable#reverse (or reverse!):
hash_data.sort_by {|hash| hash[:sortby] }.reverse
#=> [{:key1=>"valuesds6", :sortby=>6}, {:key1=>"value4", :sortby=>4}, {:key1=>"value2_data_is_here", :sortby=>2}, {:key1=>"valuedsd", :sortby=>1}]
Another option for sorting in descending order is the following - note minus sign (credits to #sagarpandya82):
hash_data.sort_by {|hash| -hash[:sortby] }
I would like to transform this
def some_process(k,v)
return "#{v}_#{k}"
end
a_hash = {
"i_love_hashes" => {
"thing" => 20,
"other_thing" => "0",
"yet_another_thing" => "i disagree",
"_peculiar_thing" => [
{"count" => 30,
"name" => "freddie"},
{"count" => 15,
"name" => "johhno"},
{"count" => 12,
"name" => "mohammed"},
]
},
"as_do_i" => {
"thing" => 10,
"other_thing" => "2",
"yet_another_thing" => "i strongly agree",
"_peculiar_thing" => [
{"count" => 10,
"name" => "frodo"},
{"count" => 4,
"name" => "bilbo"},
{"count" => 2,
"name" => "elizabeth"},
]
}
}
into this
{
"i_love_hashes"=>{
"thing"=>20,
"other_thing"=>"0",
"yet_another_thing"=>"i disagree",
"_peculiar_thing"=> [
{"count"=>30, "name"=>"freddie", :sinister_name=>"freddie_i_love_hashes"},
{"count"=>15, "name"=>"johhno", :sinister_name=>"johhno_i_love_hashes"},
{"count"=>12, "name"=>"mohammed", :sinister_name=>"mohammed_i_love_hashes"}
]},
"as_do_i"=>{
"thing"=>10,
"other_thing"=>"2",
"yet_another_thing"=>"i strongly agree",
"_peculiar_thing"=>[
{"count"=>10, "name"=>"frodo", :sinister_name=>"frodo_as_do_i"},
{"count"=>4, "name"=>"bilbo", :sinister_name=>"bilbo_as_do_i"},
{"count"=>2, "name"=>"elizabeth", :sinister_name=>"elizabeth_as_do_i"}
]
}
}
this is the code I am currently using to achieve this
a_hash.each_with_object({}) do |(k,v),o|
o.merge!({k =>
v.each_with_object({}) do |(a,b),g|
g.merge!({ a =>
(b.is_a?(Array) ? b.collect {|x| x.merge({sinister_name: (some_process k, x["name"])})} : b)
})
end
})
end
Ignoring the specific details of what is being returned by "some_process" (what is important is that it depends on the outer most key and the inner name values, in this example), are there any alternatives that would be considered more elegant?
Why not do a recursive function?
def add_siniter(hash)
hash[:siniter_name] = "#{hash['name']}_i_love_hashes"
hash
end
def format_hash(item)
case item
when Hash then item.keys.each{|key| format_hash(item[key])}
when Array then item.map!{|h| add_siniter(h)}
end
end
format_hash(a_hash)
How would I save this array in one call with Rails?
tax_rates = [{
:income_from => 0
:income_to => 18200
:start => "01-07-2013"
:finish => "30-06-2014"
:rate => nil
:premium => nil
},{
:income_from => 18201
:income_to => 37000
:start => "01-07-2013"
:finish => "30-06-2014"
:rate => 0.19
:premium => nil
},{
:income_from => 18201
:income_to => 37000
:start => "01-07-2013"
:finish => "30-06-2014"
:rate => 0.19
:premium => nil
}]
Can I just call Rails.create(tax_rates)?
Also, is there a way to remove duplicate symbols so they look neater?
Your example is almost correct.
Use ActiveRecord::Persistence#create, which can accept an array of hashes as a parameter.
tax_rates = [
{
income_from: 0,
income_to: 18200,
start: "01-07-2013",
finish: "30-06-2014",
rate: nil,
premium: nil,
},
{
income_from: 18201,
income_to: 37000,
start: "01-07-2013",
finish: "30-06-2014",
rate: 0.19,
premium: nil,
},
# ...
]
TaxRate.create(tax_rates) # Or `create!` to raise if validations fail
A nice solution is to use the active record import gem. I recommend it over now built-in Rails bulk insert because it's more flexible in the options in case of constraint violation.
TaxRate.import(
[:income_from, :income_to, :start, :finish, :rate, :premium],
tax_rates
)
Its definitely better than my old answer which would trigger a db commit per entry in the array :)
Old answer:
tax_rates.map {|tax_rate| TaxRate.new(tax_rate).save }
This way you'll retrieve an Array with true or false to know which did succeed and which didn't.
If you want all of them to be saved .or, non of them to be saved even if one fails, you can use 'ActiveRecord::Base.transaction'
e.g.
ActiveRecord::Base.transaction do
tax_rate.each do |tax_rt|
TaxRate.new(tax_rt).save
end
end
I am not sure about rails < 4.2 but I have tried it in rails 4.2 you can simply do this
TaxRate.create(tax_rt)
Here is an example like yours:
a = []
a << B.new(:name => "c")
a << B.new(:name => "s")
a << B.new(:name => "e")
a << B.new(:name => "t")
The array is saved all at once with:
a.each(&:save)
This will call B#save on each item in the array.
use a gem 'fast_inserter': https://github.com/joinhandshake/fast_inserter
it generates a single sql query of thousand records.
movie_data = [1, 'Climates (Iklimler)', 'Clay Pauwel', 'Drama'],
[2, 'Tinpis Run', 'Andros Glazer', 'Comedy'],
[3, 'Naked City, The', 'Bethena Chatband', 'Mystery'],
[4, 'Small Time Crooks', 'Naomi Plom', 'Crime'],
[5, 'Shadowboxer', 'Georgeanne Widdicombe', 'Thriller']
params = {
table: 'movies',
static_columns: {
created_at: '0000-00-00 00:00:00',
updated_at: '0000-00-00 00:00:00',
},
options: {
timestamps: false,
unique: true,
check_for_existing: true
},
group_size: 100,
variable_columns: %w(id title director description),
values: movie_data
}
inserter = FastInserter::Base.new(params)
inserter.fast_insert
I've got a model User which has id, name, surname, role_id, permission_id
Here is few user entries :
User => {:name => 'Bob', :surname => 'surnmae', :role_id => 1, :permission_id = 2}
User => {:name => 'Alice', :surname => 'strange', :role_id => 1, :permission_id = 3}
User => {:name => 'Ted', :surname => 'Teddy', :role_id => 2, :permission_id = 3}
Now I need to group them first by role_id and then by permission_id, here is what I mean :
Category.select([:name, :role_id, :permission_id]).group_by(&:role_id)
Produces :
{1 =>
[#<User name: "Bob", role_id: 1, permission_id: 2>,
#<User name: "Alice", role_id: 1, permission_id: 3>]
2 => [#<User name: "Ted", role_id: 2, permission_id: 3>]
}
Which is close enough but I need them grouped with permission_id as well so it would look like this :
{:role_id => {:permision_id => [Array of users grouped by this criteria]}
}
It is bit more tricky than it seems. It is better to write it into multiple steps. However, the following one-liner will work:
Hash[ User.all.group_by(&:role_id).collect{|role, grp| [role, grp.group_by(&:permission_id)]} ]
Output will be the following (which is probably what you are looking for):
{1=>
{2=>[{:name=>"Bob", :surname=>"surnmae", :role_id=>1, :permission_id=>2}],
3=>[{:name=>"Alice", :surname=>"strange", :role_id=>1, :permission_id=>3}]},
2=>{3=>[{:name=>"Ted", :surname=>"Teddy", :role_id=>2, :permission_id=>3}]}}
Same logic, but simpler to comprehend:
output={}
User.all.group_by(&:role_id).each{|role, grp| output[role]= grp.group_by(&:permission_id)}
# output has required goruping
maybe something like
Category.select([:name, :role_id, :permission_id]).group_by(&:role_id).map{|role| role.group_by(&:permission_id)}
Category.select([:name, :role_id, :permission_id]).group_by { |category| [category.role_id, category.permission_id] }
Edit: Nevermind, this doesn't provide quite the formatting you're looking for.