I have array of nested hash that is,
#a = [{"id"=>"5", "head_id"=>nil,
"children"=>
[{"id"=>"19", "head_id"=>"5",
"children"=>
[{"id"=>"21", "head_id"=>"19", "children"=>[]}]},
{"id"=>"20", "head_id"=>"5",
"children"=>
[{"id"=>"22", "head_id"=>"20", "children"=>[]}, {"id"=>"23"}]
}]
}]
I need array of all values which have key name 'id'. like #b = [5,19,21,20,22,23]
I have already try this '#a.find { |h| h['id']}`.
Is anyone know how to get this?
Thanks.
You can create new method for Array class objects.
class Array
def find_recursive_with arg, options = {}
map do |e|
first = e[arg]
unless e[options[:nested]].blank?
others = e[options[:nested]].find_recursive_with(arg, :nested => options[:nested])
end
[first] + (others || [])
end.flatten.compact
end
end
Using this method will be like
#a.find_recursive_with "id", :nested => "children"
It can be done like this, using recursion
def traverse_hash
values = []
#a = [{"id"=>"5", "head_id"=>nil,
"children"=>
[{"id"=>"19", "head_id"=>"5",
"children"=>
[{"id"=>"21", "head_id"=>"19", "children"=>[]}]},
{"id"=>"20", "head_id"=>"5",
"children"=>
[{"id"=>"22", "head_id"=>"20", "children"=>[]}, {"id"=>"23"}]
}]
}]
get_values(#a)
end
def get_values(array)
array.each do |hash|
hash.each do |key, value|
(value.is_a?(Array) ? get_values(value) : (values << value)) if key.eql? 'id'
end
end
end
Related
I've got a class that looks like this that turns a collection into a nested array of hashes:
# variable_stack.rb
class VariableStack
def initialize(document)
#document = document
end
def to_a
#document.template.stacks.map { |stack| stack_hash(stack) }
end
private
def stack_hash(stack)
{}.tap do |hash|
hash['stack_name'] = stack.name.downcase.parameterize.underscore
hash['direction'] = stack.direction
hash['boxes'] = stack.boxes.indexed.map do |box|
box_hash(box)
end.reverse_if(stack.direction == 'up') # array extensions
end.delete_if_key_blank(:boxes) # hash extensions
end
def box_hash(box)
{}.tap do |hash|
hash['box'] = box.name.downcase.parameterize.underscore
hash['content'] = box.template_variables.indexed.map do |var|
content_array(var)
end.join_if_any?
end.delete_if_key_blank(:content)
end
def content_array(var)
v = #document.template_variables.where(master_id: var.id).first
return unless v
if v.text.present?
v.text
elsif v.photo_id.present?
v.image.uploaded_image.url
else
''
end
end
end
# array_extensions.rb
class Array
def join_if_any?
join("\n") if size.positive?
end
def reverse_if(boolean)
reverse! if boolean
end
end
# hash_extensions.rb
class Hash
def delete_if_key_blank(key)
delete_if { |_, _| key.to_s.blank? }
end
end
This method is supposed to return a hash that looks like this:
"stacks": [
{
"stack_name": "stack1",
"direction": "down",
"boxes": [
{
"box": "user_information",
"content": "This is my name.\n\nThis is my phone."
}
},
{
"stack_name": "stack2",
"direction": "up",
"boxes": [
{
"box": "fine_print",
"content": "This is a test.\n\nYeah yeah."
}
]
}
Instead, often the boxes key is null:
"stacks": [
{
"stack_name": "stack1",
"direction": "down",
"boxes": null
},
{
"stack_name": "stack2",
"direction": "up",
"boxes": [
{
"box": "fine_print",
"content": "This is a test.\n\nYeah yeah."
}
]
}
I suspect it's because I can't "single-line" adding to arrays in Rails 5 (i.e., they're frozen). The #document.template.stacks is an ActiveRecord collection.
Why can't I map records in those collections into hashes and add them to arrays like hash['boxes']?
The failing test
APIDocumentV3 Instance methods #stacks has the correct content joined and indexed
Failure/Error:
expect(subject.stacks.first['boxes'].first['content'])
.to include(document.template_variables.first.text)
expected "\n" to include "#1"
Diff:
## -1,2 +1 ##
-#1
The presence of \n means the join method works, but it shouldn't join if the array is empty. What am I missing?
reverse_if returns nil if the condition is false. Consider this:
[] if false #=> nil
You could change it like this:
def reverse_if(condition)
condition ? reverse : self
end
delete_if_key_blank doesn't look good for me. It never deletes anything.
Disclaimer. I don't think it's a good idea to extend standard library.
So thanks to Danil Speransky I solved this issue, although what he wrote doesn't quite cover it.
There were a couple of things going on here and I solved the nil arrays with this code:
hash['boxes'] = stack.boxes.indexed.map do |box|
box_hash(box) unless box_hash(box)['content'].blank?
end.reverse_if(stack.direction == 'up').delete_if_blank?
end
That said, I'm almost certain my .delete_if_blank? extension to the Array class isn't helping at all. It looks like this, FYI:
class Array
def delete_if_blank?
delete_if(&:blank?)
end
end
I solved it by thowing the unless box_hash(box)['content'].blank? condition on the method call. It ain't pretty but it works.
How can I remove all values from ruby has. I don't want to remove keys just values.
For example:
here is my hash: {'a'=>{'b'=>'c'},'d'=>'e','f'=>{'g'=>''}}
I want this: {'a'=>{'b'=>nil},'d'=>nil,'f'=>{'g'=>nil}}
I don't want to delete the nested hashes. The nesting level varies from one to six levels
thanx
You can write custom delete_values! method, like this:
class Hash
def delete_values!
each_key do |key|
self[key].is_a?(Hash) ? self[key].delete_values! : self[key] = nil
end
end
end
{'a'=>{'b'=>'c'},'d'=>'e','f'=>{'g'=>''}}.delete_values!
# => {"a"=>{"b"=>nil}, "d"=>nil, "f"=>{"g"=>nil}}
h = {'a'=>{'b'=>'c'},'d'=>'e','f'=>{'g'=>''}}
def clean_hash h
h.each do |key, value|
if value.instance_of? Hash
clean_hash value
else
h[key] = nil
end
end
end
clean_hash h
#{"a"=>{"b"=>nil}, "d"=>nil, "f"=>{"g"=>nil}}
h = {'a'=>{'b'=>'c'},'d'=>'e','f'=>{'g'=>''}}
def cleaned_hash(h)
h.reduce({}) do |memo, (key, val)|
memo[key] = if val.is_a? Hash
cleaned_hash(val)
else
nil
end
memo
end
end
cleaned_hash h
# => {"a"=>{"b"=>nil}, "d"=>nil, "f"=>{"g"=>nil}}
This will not modify your hash but instead give you cleaned copy
I have the following snippet of code to fetch certain columns from the db:
#data = Topic.select("id,name").where("id in (?)",#question.question_topic.split(",")).map(&:attributes)
In the resulting Array of Hashes which is :
Current:
#data = [ { "id" => 2, "name" => "Sports" }]
To be changed to:
#data = [ { "id" => "2", "name" => "Sports" }]
I want to convert "id" to string from fixnum. Id is integer in the db. What is the cleanest way to do this?
Note: After using .map(&:attributes) it is not an active record relation.
You can do it with proper map usage:
topics = Topic.select("id,name").where("id in (?)",#question.question_topic.split(","))
#data = topics.map do |topic|
{
'id' => topic.id.to_s,
'name' => topic.name
}
end
What you're looking for is simply
#data.each { |obj| obj["id"] = obj["id"].to_s }
There isn't really a simpler way (I think that's straightforward enough anyway).
Going by the title which implies a different question - converting every value in the hash to a string you can do this:
#data.each do |obj|
obj.map do |k, v|
{k => v.to_s}
end
end
Just leaving that there anyway.
You can use Ruby's #inject here:
#data.map do |datum|
new_datum = datum.inject({}) do |converted_datum, (key, value)|
converted_datum[key] = value.to_s
converted_datum
end
end
This will work to convert all values to strings, regardless of the key.
If you are using Rails it can be even cleaner with Rails' #each_with_object:
#data.map do |datum|
datum.each_with_object({}) do |(key, value), converted_datum|
converted_datum[key] = value.to_s
end
end
This will iterate all the key names in the hash and replace the value with the #to_s version of the datum associated with the key. nil's converted to empty strings. Also, this assumes you don't have complex data within the hash like embedded arrays or other hashes.
def hash_values_to_string(hash)
hash.keys.each {|k| hash[k]=hash[k].to_s}; hash
end
Here's a sample of array:
{"C1"=>[
{:upc=>"51857195821952", :product_id=>"1234", :name=>"name", :price=>" $15 ", :color=>"green", :size=>"L", :description=>"descr"},
{:upc=>"352353wegs", :product_id=>"456", :name=>"name2", :price=>"$21", :color=>"black", :size=>"S", :description=>"descr"}, # ...
],
#...
}
And here as I am trying to fetch data from that array:
#array.each do |p|
product = Product.new
product.sku = p[0]
product.name = p[1][0][:name] #can't convert Symbol into Integer
price = p[1].select{ |pr| !pr[:price].nil? and pr[:price] != "0" }.min_by{ |i| i[:price].to_f }[:price]
product.price = "%.2f" % (price.to_f)
...
end
Every time I try to fetch data from the array, I get on the line product.name = the error can't convert Symbol into Integer.
What is wrong in this case? I spent a part of afternoon on this issue, but unfortunately I still cannot figure out it...
Thanky you
Your #array is actually a hash. It is formated like following:
{
'name1' => [{:upc => "..."},{:upc => "..."}],
'name2' => [{:upc => "..."},{:upc => "..."}],
#...
}
Since it is a Hash, you can use 2 arguments in the each (works for map also) method (one for the key, the other for the value):
#array.each do |name, array|
product = Product.new
product.sku = name # returns "C1"
array.each do |data|
data[:upc]
data[:name]
#etc...
end
end
The fundamental problem is that the sample array you showed above is not actually an array. It's a hash with key-value pairs. Therefore, your code like p[0] or p[1][0] doesn't make sense because a hash doesn't have index like array. Hash is not ordered. Hashes values are accessed with a "key" rather than an "index" like array.
Iterating through key-value pairs of a hash is done something like this.
1.9.3p194 :001 > x = {:x => 10, :y => 9, :z => 10}
=> {:x=>10, :y=>9, :z=>10}
1.9.3p194 :002 > x.each do |key, value|
1.9.3p194 :003 > puts "#{key} : #{value}"
1.9.3p194 :004?> end
x : 10
y : 9
z : 10
=> {:x=>10, :y=>9, :z=>10}
It looks like you may be confusing Arrays and Hashes a bit.
Given this:
#array = {"C1"=>[
{:upc=>"51857195821952", :product_id=>"1234", :name=>"name", :price=>" $15 ", :color=>"green", :size=>"L", :description=>"descr"},
{:upc=>"352353wegs", :product_id=>"456", :name=>"name2", :price=>" $21 ", :color=>"black", :size=>"S", :description=>"descr"}
] }
Then #array.class.name is Hash
You can get the actual array by accessing it like so:
#actual_array = #array["C1"]
Then, #actual_array.class.name will be Array
So, taking this approach and re-writing:
#array = {"C1"=>[
{:upc=>"51857195821952", :product_id=>"1234", :name=>"name", :price=>" $15 ", :color=>"green", :size=>"L", :description=>"descr"},
{:upc=>"352353wegs", :product_id=>"456", :name=>"name2", :price=>" $21 ", :color=>"black", :size=>"S", :description=>"descr"}
] }
#actual_array = #array["C1"]
#actual_array.each do |p|
puts p[:name]
end
If you do this, you'll find that the value of the :name element will be printed neatly out.
I am wondering what is the best way to convert a json formatted key value pair to ruby hash with symbol as key:
example:
{ 'user': { 'name': 'foo', 'age': 40, 'location': { 'city' : 'bar', 'state': 'ca' } } }
==>
{ :user=>{ :name => 'foo', :age =>'40', :location=>{ :city => 'bar', :state=>'ca' } } }
Is there a helper method can do this?
using the json gem when parsing the json string you can pass in the symbolize_names option. See here: http://flori.github.com/json/doc/index.html (look under parse)
eg:
>> s ="{\"akey\":\"one\",\"bkey\":\"two\"}"
>> JSON.parse(s,:symbolize_names => true)
=> {:akey=>"one", :bkey=>"two"}
Leventix, thank you for your answer.
The Marshal.load(Marshal.dump(h)) method probably has the most integrity of the various methods because it preserves the original key types recursively.
This is important in case you have a nested hash with a mix of string and symbol keys and you want to preserve that mix upon decode (for instance, this could happen if your hash contains your own custom objects in addition to highly complex/nested third-party objects whose keys you cannot manipulate/convert for whatever reason, like a project time constraint).
E.g.:
h = {
:youtube => {
:search => 'daffy', # nested symbol key
'history' => ['goofy', 'mickey'] # nested string key
}
}
Method 1: JSON.parse - symbolizes all keys recursively => Does not preserve original mix
JSON.parse( h.to_json, {:symbolize_names => true} )
=> { :youtube => { :search=> "daffy", :history => ["goofy", "mickey"] } }
Method 2: ActiveSupport::JSON.decode - symbolizes top-level keys only => Does not preserve original mix
ActiveSupport::JSON.decode( ActiveSupport::JSON.encode(h) ).symbolize_keys
=> { :youtube => { "search" => "daffy", "history" => ["goofy", "mickey"] } }
Method 3: Marshal.load - preserves original string/symbol mix in the nested keys. PERFECT!
Marshal.load( Marshal.dump(h) )
=> { :youtube => { :search => "daffy", "history" => ["goofy", "mickey"] } }
Unless there is a drawback that I'm unaware of, I'd think Method 3 is the way to go.
Cheers
There isn't anything built in to do the trick, but it's not too hard to write the code to do it using the JSON gem. There is a symbolize_keys method built into Rails if you're using that, but that doesn't symbolize keys recursively like you need.
require 'json'
def json_to_sym_hash(json)
json.gsub!('\'', '"')
parsed = JSON.parse(json)
symbolize_keys(parsed)
end
def symbolize_keys(hash)
hash.inject({}){|new_hash, key_value|
key, value = key_value
value = symbolize_keys(value) if value.is_a?(Hash)
new_hash[key.to_sym] = value
new_hash
}
end
As Leventix said, the JSON gem only handles double quoted strings (which is technically correct - JSON should be formatted with double quotes). This bit of code will clean that up before trying to parse it.
Recursive method:
require 'json'
def JSON.parse(source, opts = {})
r = JSON.parser.new(source, opts).parse
r = keys_to_symbol(r) if opts[:symbolize_names]
return r
end
def keys_to_symbol(h)
new_hash = {}
h.each do |k,v|
if v.class == String || v.class == Fixnum || v.class == Float
new_hash[k.to_sym] = v
elsif v.class == Hash
new_hash[k.to_sym] = keys_to_symbol(v)
elsif v.class == Array
new_hash[k.to_sym] = keys_to_symbol_array(v)
else
raise ArgumentError, "Type not supported: #{v.class}"
end
end
return new_hash
end
def keys_to_symbol_array(array)
new_array = []
array.each do |i|
if i.class == Hash
new_array << keys_to_symbol(i)
elsif i.class == Array
new_array << keys_to_symbol_array(i)
else
new_array << i
end
end
return new_array
end
Of course, there is a json gem, but that handles only double quotes.
Another way to handle this is to use YAML serialization/deserialization, which also preserves the format of the key:
YAML.load({test: {'test' => { ':test' => 5}}}.to_yaml)
=> {:test=>{"test"=>{":test"=>5}}}
Benefit of this approach it seems like a format that is better suited for REST services...
The most convenient way is by using the nice_hash gem: https://github.com/MarioRuiz/nice_hash
require 'nice_hash'
my_str = "{ 'user': { 'name': 'foo', 'age': 40, 'location': { 'city' : 'bar', 'state': 'ca' } } }"
# on my_hash will have the json as a hash
my_hash = my_str.json
# or you can filter and get what you want
vals = my_str.json(:age, :city)
# even you can access the keys like this:
puts my_hash._user._location._city
puts my_hash.user.location.city
puts my_hash[:user][:location][:city]
If you think you might need both string and symbol keys:
JSON.parse(json_string).with_indifferent_access