Rewriting the question with detailed example:
I have array of objects with three property, I would like to build array of harsh and have the resulting hash not have #name instance property. I have simulated the problem with an example.
example creation
class Employee
attr_accessor :name, :company, :duration
def initialize(name, company, duration)
#name = name
#company = company
#duration = duration
end
end
aSong1 = Employee.new("Fleck", "AMZ", 260)
aSong2 = Employee.new("Taylor", "EMC", 120)
aSong3 = Employee.new("Bob", "Adobe", 260)
aSong4 = Employee.new("Jack", "Google", 360)
final_array = [ ]
final_array.push(aSong1)
final_array.push(aSong2)
final_array.push(aSong3)
final_array.push(aSong4)
controller
puts final_array.length #4
final_array.each do | element |
puts element.is_a?(Object) #true
puts element.name #prints name
end
resulting array ( expected )
result = [{company: 'AMZ',duration: 260}, {company: 'EMC',duration: 120},{company: 'Adobe',duration: 260}, {company: 'Google',duration: 360} ]
Example: repl
You can delete the id keys using
a = [{"id":"21","company":"AMC","name":"Matt"},{"id":"22","company":"AMC","name":"Jon"},
{"id":"12","company":"XYZ","name":"Bob"}].each{|o| o.delete :id}
If you want to compare it with other hashes you can use the merge method assuming a2 is the second Hash
a.merge(a2)
This will return a new hash with any matching keys updated with new corresponding values from the second hash
final_array.collect {|x| { company: x.company, duration: x.duration }}
result:
[{:company=>"AMZ", :duration=>260}, {:company=>"EMC", :duration=>120}, {:company=>"Adobe", :duration=>260}, {:company=>"Google", :duration=>360}]
How about the following?
class Employee
def to_h
instance_variables.each_with_object({}) do |var, h|
k = var.to_s.tr('#','').to_sym
v = instance_variable_get(var)
h[k] = v
end
end
end
result = final_array.map{|e| e.to_h.delete_if{|k,v| k == :name}}
Related
I am trying to run following query through Rails query interface but unable to translate my logic. The query is
Select f.* from feeds f
Left join feed_items fi on fi.id = f.feedable_id
where
f.feedable_type in ('Homework', 'Datesheet')
and
(
(fi.assignable_type = 'Level' and assignable_id IN (1)) or
(fi.assignable_type = 'Student' and assignable_id IN (1)) or
(fi.assignable_type = 'Section' and assignable_id IN (1))
)
Scenario:
I receive following params hash in my action containing filters which will be added dynamically in my query
{"page"=>"1", "limit"=>"2", "type_filter"=>["Homework", "Datesheet"], "assignable_filter"=>{"Student"=>"[2]", "Section"=>"[1]", "Level"=>"[1]"}}
So far, what I have done is joining the tables and added where clause for type filter but not sure how to dynamically add assignable_filters. Here is my rails code, options are params in following code
def get_feeds(options)
base = Feed.includes(:feed_item)
base = add_type_filters base, options
base = add_assignable_filters base, options
format_response base, options
end
def add_type_filters(base, options)
type_filter = options[:type_filter]
if !type_filter.nil? and type_filter.length > 0
base = base.where('feedable_type IN (?)', options[:type_filter])
end
base
end
def add_assignable_filters(base, options)
assignable_filter = options[:assignable_filter]
if !assignable_filter.nil?
assignable_filter.each do |key, value|
# code for adding filters combined with or conditions
end
# wrap the or conditions and join them with an and in main where clause
end
base
end
P.S I am using rails 5
There was no straight forward way of building the query dynamically. I had to construct the where string to solve the problem. My current solution is
def get_feeds(options)
params_hash = {}
type_filters = add_type_filters options, params_hash
assignable_filters = add_assignable_filters options, params_hash
where = type_filters
where = where ? "#{where} and (#{assignable_filters})" : assignable_filters
base = Feed.eager_load(:feed_item).where(where, params_hash)
format_response base, options
end
def add_type_filters(options, params_hash)
type_filter = options[:type_filter]
type_filter_sql = nil
if !type_filter.nil? and type_filter.length > 0
type_filter_sql = 'feeds.feedable_type in (:type_filter)'
params_hash[:type_filter] = type_filter
end
type_filter_sql
end
def add_assignable_filters(options, params_hash)
assignable_filter_sql = []
assignable_filter = options[:assignable_filter]
if !assignable_filter.nil?
assignable_filter.each do |key, value|
assignable_filter_sql.push("(feed_items.assignable_type = '#{key}' and feed_items.assignable_id IN (:#{key}))")
params_hash[key.to_sym] = JSON.parse(value)
end
end
assignable_filter_sql.join(' or ')
end
I have an array of hashes - #profiles which has data as:
[{:user_id=>5, :full_name=>"Emily Spot"},{:user_id=>7, :full_name=>"Kevin Walls"}]
I want to get full_name of say user_id = 7? I'm doing the following: but it's throwing an error that expression #profiles.find{|h| h[':user_id'] == current_user.id} is nil.
name = #profiles.find{ |h| h[':user_id'] == current_user.id }[':full_name']
if I use select instead of find then error is - no implicit conversion of String into Integer.
How do I search through the array of hashes?
UPDATE:
After #Eric's answer, I restructured my job model & view actions:
def full_names
profile_arr||= []
profile_arr = self.applications.pluck(:user_id)
#profiles = Profile.where(:user_id => profile_arr).select([:user_id, :first_name, :last_name]).map {|e| {user_id: e.user_id, full_name: e.full_name} }
#full_names = #profiles.each_with_object({}) do |profile, names|
names[profile[:user_id]] = profile[:full_name]
end
end
In the view....,
p #current_job.full_names[current_user.id]
#profiles is an array of hashes, with symbols as keys, whereas what you use is String objects.
So ':user_id' is a string, and you want symbol: :user_id:
#profiles.find{ |h| h[:user_id] == current_user.id }
I want to get full_name of say user_id == 7
#profiles.find { |hash| hash[:user_id] == 7 }.fetch(:full_name, nil)
Note, I used Hash#fetch for case, when there is no hash with value 7 at key :user_id.
As you've noticed, it's not very convenient to extract the name of user_id 7. You could modify your data structure a bit :
#profiles = [{:user_id=>5, :full_name=>"Emily Spot"},
{:user_id=>7, :full_name=>"Kevin Walls"}]
#full_names = #profiles.each_with_object({}) do |profile, names|
names[profile[:user_id]] = profile[:full_name]
end
p #full_names
# {5=>"Emily Spot", 7=>"Kevin Walls"}
p #full_names[7]
# "Kevin Walls"
p #full_names[6]
# nil
You didn't lose any information but name look-up is now much faster, easier and more robust.
Suggesting, to create a new hash that can make things simpler
Eg:
results = {}
profiles = [
{user_id: 5, full_name: "Emily Spot"},
{user_id: 7, full_name: "Kevin Walls"}
]
profiles.each do |details|
results[details[:user_id]] = details[:full_name]
end
Now, results will have:
{5: "Emily Spot", 7: "Kevin Walls"}
So, if you need to get full_name of say user_id = 7, simply do:
results[7] # will give "Kevin Walls"
I seem lost trying to achieve the following, I tried all day please help
I HAVE
h = {
"kv1001"=> {
"impressions"=>{"b"=>0.245, "a"=>0.754},
"visitors" =>{"b"=>0.288, "a"=>0.711},
"ctr" =>{"b"=>0.003, "a"=>0.003},
"inScreen"=>{"b"=>3.95, "a"=>5.031}
},
"kv1002"=> {
"impressions"=>{"c"=>0.930, "d"=>0.035, "a"=>0.004, "b"=>0.019,"e"=>0.010},
"visitors"=>{"c"=>0.905, "d"=>0.048, "a"=>0.005, "b"=>0.026, "e"=>0.013},
"ctr"=>{"c"=>0.003, "d"=>0.006, "a"=>0.004, "b"=>0.003, "e"=>0.005},
"inScreen"=>{"c"=>4.731, "d"=>4.691, "a"=>5.533, "b"=>6.025, "e"=>5.546}
}
}
MY GOAL
{
"segment"=>"kv1001=a",
"impressions"=>"0.754",
"visitors"=>"0.711",
"inScreen"=>"5.031",
"ctr"=>"0.003"
}, {
"segment"=>"kv1001=b",
"impressions"=>"0.245",
"visitors"=>"0.288",
"inScreen"=>"3.95",
"ctr"=>"0.003"
}, {
"segment"=>"kv1002=a",
"impressions"=>"0.004"
#... etc
}
My goal is to create a hash with 'kv1001=a' i.e the letters inside the hash and assign the keys like impressions, visitors etc. The example MY GOAL has the format
So format type "kv1001=a" must be constructed from the hash itself, a is the letter inside the hash.
I have solved this now
`data_final = []
h.each do |group,val|
a = Array.new(26){{}}
val.values.each_with_index do |v, i|
keys = val.keys
segment_count = v.keys.length
(0..segment_count-1).each do |n|
a0 = {"segment" => "#{group}=#{v.to_a[n][0]}", keys[i] => v.to_a[n][1]}
a[n].merge! a0
if a[n].count > 4
data_final << a[n]
end
end
end
end`
Here's a simpler version
h.flat_map do |segment, attrs|
letters = attrs.values.flat_map(&:keys).uniq
# create a segment entry for each unique letter
letters.map do |letter|
seg = {"segment" => "#{segment}=#{letter}"}
seg.merge Hash[attrs.keys.map {|key| [key,attrs[key][letter]]}]
end
end
Output:
[{"segment"=>"kv1001=b",
"impressions"=>0.245,
"visitors"=>0.288,
"ctr"=>0.003,
"inScreen"=>3.95},
{"segment"=>"kv1001=a",
"impressions"=>0.754,
"visitors"=>0.711,
"ctr"=>0.003,
"inScreen"=>5.031},
{"segment"=>"kv1002=c",
"impressions"=>0.93,
"visitors"=>0.905,
"ctr"=>0.003,
"inScreen"=>4.731},
{"segment"=>"kv1002=d",
"impressions"=>0.035,
"visitors"=>0.048,
"ctr"=>0.006,
"inScreen"=>4.691},
{"segment"=>"kv1002=a",
"impressions"=>0.004,
"visitors"=>0.005,
"ctr"=>0.004,
"inScreen"=>5.533},
{"segment"=>"kv1002=b",
"impressions"=>0.019,
"visitors"=>0.026,
"ctr"=>0.003,
"inScreen"=>6.025},
{"segment"=>"kv1002=e",
"impressions"=>0.01,
"visitors"=>0.013,
"ctr"=>0.005,
"inScreen"=>5.546}]
I need to return to my Rails view more than one variable from method... But how could i do this?
For example now i have
def my1
#price = 1
#price
end
but how could i also return other valuem somethin like:
def my1
#qnt = 2
#price = 1
#price, #qnt
end
?
Also my idea is to split them to string like
#price + "/-/" + #qnt
and then just split them via /-/ in view.... But this is a bad practice...
So how could i get from one method two or more variables?
Return an array:
def my1
qnt = 2
price = 1
[price, qnt]
end
then you can do this:
p, q = my1() # parentheses to emphasize a method call
# do something with p and q
Option 2
Or you can return a custom object, like this:
require 'ostruct'
def my1
qnt = 2
price = 1
OpenStruct.new(price: price, quantity: qnt)
end
res = my1() # parentheses to emphasize a method call
res.quantity # => 2
res.price # => 1
Use another object that will hold the variables and return it. You can then access the variables from that object;
Array
The easiest way is to return an Array:
def my1
#qnt = 2
#price = 1
[ #price, #qnt ]
end
price, quantity = my1
Hash
But you could also return a Hash:
def my1
#qnt = 2
#price = 1
{ :quantity => #qnt, :price = #price
end
return_value = my1
price = return_value[:price]
quantity = return_value[:quantity]
# or
price, quantity = [ return_value[:price], return_value[:quantity] ]
Custom Class
Or a custom Class:
class ValueHolder
attr_reader :quantity, :price
def initialize(quantity, price)
#quantity = quantity
#price = price
end
end
def my1
#qnt = 2
#price = 1
ValueHolder.new(#qnt, #price)
end
value_holder = my1
price = value_holder.price
quantity = value_holder.quantity
# or
price, quantity = [ value_holder.price, value_holder.quantity ]
OpenStruct
You could use OpenStruct as Sergio mentioned.
I have this code here and it works but there has to be a better way.....i need two arrays that look like this
[
{
"Vector Arena - Auckland Central, New Zealand" => {
"2010-10-10" => [
"Enter Sandman",
"Unforgiven",
"And justice for all"
]
}
},
{
"Brisbane Entertainment Centre - Brisbane Qld, Austr..." => {
"2010-10-11" => [
"Enter Sandman"
]
}
}
]
one for the past and one for the upcoming...the problem i have is i am repeating myself and though it works i want to clean it up ...here is my data
..
Try this:
h = Hash.new {|h1, k1| h1[k1] = Hash.new{|h2, k2| h2[k2] = []}}
result, today = [ h, h.dup], Date.today
Request.find_all_by_artist("Metallica",
:select => "DISTINCT venue, showdate, LOWER(song) AS song"
).each do |req|
idx = req.showdate < today ? 0 : 1
result[idx][req.venue][req.showdate] << req.song.titlecase
end
Note 1
In the first line I am initializing an hash of hashes. The outer hash creates the inner hash when a non existent key is accessed. An excerpt from Ruby Hash documentation:
If this hash is subsequently accessed by a key that doesn‘t correspond to a hash
entry, the block will be called with the hash object and the key, and should
return the default value. It is the block‘s responsibility to store the value in
the hash if required.
The inner hash creates and empty array when the non existent date is accessed.
E.g: Construct an hash containing of content as values and date as keys:
Without a default block:
h = {}
list.each do |data|
h[data.date] = [] unless h[data.date]
h[data.date] << data.content
end
With a default block
h = Hash.new{|h, k| h[k] = []}
list.each do |data|
h[data.date] << data.content
end
Second line simply creates an array with two items to hold the past and future data. Since both past and the present stores the data as Hash of Hash of Array, I simply duplicate the value.
Second line can also be written as
result = [ h, h.dup]
today = Date.today