I now have a JSON string:
[{"id":1,"name":"good","created_at":"2014-07-28T19:45:50.440Z","updated_at":"2014-07-28T19:45:50.440Z"},{"id":2,"name":"better","created_at":"2014-07-28T19:45:50.447Z","updated_at":"2014-07-28T19:45:50.447Z"},{"id":3,"name":"best","created_at":"2014-07-28T19:45:50.449Z","updated_at":"2014-07-28T19:45:50.449Z"}]
And I have an array:
id = ["1", "3"]
I want to check for the common IDs and print the associated name. For the above example I want my output to be:
["good","best"]
I want the output preferably to be an array. Is there a easy way to do this? I have been writing too much code to get this done and feel it should be easily done. Any suggestions?
# initiate json string
json = %q([{"id":1,"name":"good","created_at":"2014-07-28T19:45:50.440Z","updated_at":"2014-07-28T19:45:50.440Z"},{"id":2,"name":"better","created_at":"2014-07-28T19:45:50.447Z","updated_at":"2014-07-28T19:45:50.447Z"},{"id":3,"name":"best","created_at":"2014-07-28T19:45:50.449Z","updated_at":"2014-07-28T19:45:50.449Z"}])
ids = ["1", "3"]
JSON.parse(json).select{|x| ids.include? x["id"].to_s}.map{|x| x["name"]}
#=> ["good", "best"]
require 'json'
def pluck(json, ids)
json_parsed = JSON.parse(json)
json_parsed.select do |obj|
ids.include?(obj['id'])
end
.map do |obj|
obj['name']
end
end
# usage
json = '[{"id":1,"name":"good","created_at":"2014-07-28T19:45:50.440Z","updated_at":"2014-07-28T19:45:50.440Z"},{"id":2,"name":"better","created_at":"2014-07-28T19:45:50.447Z","updated_at":"2014-07-28T19:45:50.447Z"},{"id":3,"name":"best","created_at":"2014-07-28T19:45:50.449Z","updated_at":"2014-07-28T19:45:50.449Z"}]'
ids = [1, 3]
pluck(json, ids)
in you controller can do this:
def method_name
render json: Model.pluck(:name).to_json
end
Related
a little help with getting data out of a string.
Assuming I executed a sql query and now have a string(which set as hash on db):
"{\"users_associated\":{\"User:4\":6,\"User:22\":28,\"User:30\":36}}"
(Which stands for User:ID : User.display_id)
How can I get a substring the includes all users ids or all their display ids, so I'll have something like 4,22,30 or 6,22,36)?
Thanks!
It's common for data systems to return data in a serialized form, i.e. using data types that facilitate transmission of data. One of these serializable data types is String, which is how your JSON data object has been received.
The first step would be to de-serialize (or parse) this String into a Hash object using JSON.parse and tease out just the data value for key "users_associated".
your_string = "{\"users_associated\":{\"User:4\":6,\"User:22\":28,\"User:30\":36}}"
hash = JSON.parse(your_string)
data = hash["users_associated"]
#=> {"User:4":6, "User:22": 28, "User:30": 36}
Hash#keys gives you an array of a hash's keys.
Hash#values gives you an array of a hash's data values.
keys = data.keys
#=> ["User:4", "User:22", "User:30"]
values = data.values
#=> [6, 28, 36]
Array#join lets you string together the contents of an array with a defined separator, , in this case.
display_ids = keys.join(',')
#=> "6,28,36"
For the User IDs, you could Array#map every element of the values array to replace every string occurrence of "User:" with "", using String#gsub.
user_ids = values.map{|user_id| user_id.gsub("User:", "")}
#=> ["4", "22", "30"]
Then, in a similar way to display_ids, we can Array#join the contents of the user_ids array to a single string.
user_ids = user_ids.join(",")
#=> "4,22,30"
You can create two helper methods. I'm leaving return values as arrays because I assume you would need to iterate on them at some point and also converting the user id's to integers.
def extract_display_ids(json)
json['users_associated'].values
end
def extract_user_ids(some_data)
json['users_associated'].keys.map{ |key| key.split(':').last.to_i }
end
some_data = JSON.parse("{\"users_associated\":{\"User:4\":6,\"User:22\":28,\"User:30\":36}}")
extract_display_ids(some_data)
#=> [6, 28, 36]
extract_user_ids(some_data)
#=> [4, 22, 30]
If possible though, I would recommend trying to get a better data format:
{ users_associated:
[{ user_id : 4, display_id:6 }, { user_id : 4, display_id:6 }]
}
I wrote class for this. If you want, you can add it to your project and use it as follows:
require 'json'
class UserSubstringExtractor
def initialize(user_json_data)
#user_json_data = user_json_data
end
def display_ids
user_data.dig('users_associated').values
end
def user_ids
user_data.dig('users_associated').keys.map { |u| u.split(':').last.to_i }
end
private
def user_data
JSON.parse(#user_json_data)
end
end
user_json_data = '{"users_associated":{"User:4":6,"User:22":28,"User:30":36}}'
extractor = UserSubstringExtractor.new(user_json_data)
p extractor.display_ids
#=> [6, 28, 36]
p extractor.user_ids
#=> [4, 22, 30]
I've created the following hash keys with values parsed from PDF into array:
columns = ["Sen", "P-Hire#", "Emp#", "DOH", "Last", "First"]
h = Hash[columns.map.with_index.to_h]
=> {"Sen"=>0, "P-Hire#"=>1, "Emp#"=>2, "DOH"=>3, "Last"=>4, "First"=>5}
Now I want to update the value of each key with 6 equivalent values from another parsed data array:
rows = list.text.scan(/^.+/)
row = rows[0].tr(',', '')
#data = row.split
=> ["2", "6", "239", "05/05/67", "Harp", "Erin"]
I can iterate over #data in the view and it will list each of the 6 values. When I try to do the same in the controller it sets the same value to each key:
data.each do |e|
h.update(h){|key,v1| (e) }
end
=>
{"Sen"=>"Harper", "P-Hire#"=>"Harper", "Emp#"=>"Harper", "DOH"=>"Harper", "Last"=>"Harper", "First"=>"Harper"
So it's setting the value of each key to the last value of the looped array...
I would just do:
h.keys.zip(#data).to_h
If the only purpose of h is as an interim step getting to the result, you can dispense with it and do:
columns.zip(#data).to_h
There are several ways to solve this problem but a more direct and straight forward way would be:
columns = ["Sen", "P-Hire#", "Emp#", "DOH", "Last", "First"]
...
#data = row.split
h = Hash.new
columns.each_with_index do |column, index|
h[column] = #data[index]
end
Another way:
h.each do |key, index|
h[key] = #data[index]
end
Like I said, there are several ways of solving the issue and the best is always going to depend on what you're trying to achieve.
I have incoming json request in this format:
{ "id":"1", "fields":{"attr1":"value1", "attr2":"value2", ... "attrN":"valueN"}}
I need to decompose json string in my controller to this:
id: 1
attr1: value1
attr2: value2
...
attrN: valueN
How can I do this? I use Rails 4. Thanks
if you wanna add entire json hash to array, you can do something like this.
arr = Array.new
json_arr = { "id":"1", "fields":{"attr1":"value1", "attr2":"value2", ... "attrN":"valueN"}}
json_arr.each do |arr|
temp_hash = Hash.new
temp_hash = arr
arr.push(arr)
end
I am not sure about your requirement.
I have array like
strings = ["by_product[]=1", "by_product[]=2", "page=1", "per_page=10", "select[]=current", "select[]=requested", "select[]=original"]
which is array of params from request
Then there is code that generates hash from array
arrays = strings.map do |segment|
k,v = segment.split("=")
[k, v && CGI.unescape(v)]
Hash[arrays]
CUrrent output -
"by_product[]": "2",
"page":"1",
"per_page":"10",
"select[]":"original"
Expected output -
"by_product[]":"1, 2",
"page":"1",
"per_page":"10",
"select[]":"current, requested, original"
The problem is - after split method there are few by_product[] and the last one just overrides any other params, so in result instead of hash with array as value of these params im getting only last one. And i'm not sure how to fix it. Any ideas? Or at least algorithms
So try this:
hash = {}
arrays = strings.map do |segment|
k,v = segment.split("=")
hash[k]||=[]
hash[k] << v
end
output is
1.9.3-p547 :025 > hash
=> {"by_product[]"=>["1", "2"], "page"=>["1"], "per_page"=>["10"], "select[]"=>["current", "requested", "original"]}
or if you want just strings do
arrays = strings.map do |segment|
k,v = segment.split("=")
hash[k].nil? ? hash[k] = v : hash[k] << ", " + v
end
Don't reinvent the wheel, CGI and Rack can already handle query strings.
Assuming your strings array comes from a single query string:
query = "by_product[]=1&by_product[]=2&page=1&per_page=10&select[]=current&select[]=requested&select[]=original"
you can use CGI::parse: (all values as arrays)
require 'cgi'
CGI.parse(query)
#=> {"by_product[]"=>["1", "2"], "page"=>["1"], "per_page"=>["10"], "select[]"=>["current", "requested", "original"]}
or Rack::Utils.parse_query: (arrays where needed)
require 'rack'
Rack::Utils.parse_nested_query(query)
# => {"by_product[]"=>["1", "2"], "page"=>"1", "per_page"=>"10", "select[]"=>["current", "requested", "original"]}
or Rack::Utils.parse_nested_query: (values without [] suffix)
require 'rack'
Rack::Utils.parse_nested_query(query)
# => {"by_product"=>["1", "2"], "page"=>"1", "per_page"=>"10", "select"=>["current", "requested", "original"]}
And if these are parameters for a Rails controller, you can just use params.
this will also work :
strings.inject({}){ |hash, string|
key, value = string.split('=');
hash[key] = (hash[key]|| []) << value;
hash;
}
output :
{"by_product[]"=>["1", "2"], "page"=>["1"], "per_page"=>["10"], "select[]"=>["current", "requested", "original"]}
As simple as that
array.map { |record| record*3 if condition }
record*3 is the resultant operation you wanna do to the array while mapping
I encounter a strange problem when trying to alter values from a Hash. I have the following setup:
myHash = {
company_name:"MyCompany",
street:"Mainstreet",
postcode:"1234",
city:"MyCity",
free_seats:"3"
}
def cleanup string
string.titleize
end
def format
output = Hash.new
myHash.each do |item|
item[:company_name] = cleanup(item[:company_name])
item[:street] = cleanup(item[:street])
output << item
end
end
When I execute this code I get: "TypeError: no implicit conversion of Symbol into Integer" although the output of item[:company_name] is the expected string. What am I doing wrong?
Your item variable holds Array instance (in [hash_key, hash_value] format), so it doesn't expect Symbol in [] method.
This is how you could do it using Hash#each:
def format(hash)
output = Hash.new
hash.each do |key, value|
output[key] = cleanup(value)
end
output
end
or, without this:
def format(hash)
output = hash.dup
output[:company_name] = cleanup(output[:company_name])
output[:street] = cleanup(output[:street])
output
end
This error shows up when you are treating an array or string as a Hash. In this line myHash.each do |item| you are assigning item to a two-element array [key, value], so item[:symbol] throws an error.
You probably meant this:
require 'active_support/core_ext' # for titleize
myHash = {company_name:"MyCompany", street:"Mainstreet", postcode:"1234", city:"MyCity", free_seats:"3"}
def cleanup string
string.titleize
end
def format(hash)
output = {}
output[:company_name] = cleanup(hash[:company_name])
output[:street] = cleanup(hash[:street])
output
end
format(myHash) # => {:company_name=>"My Company", :street=>"Mainstreet"}
Please read documentation on Hash#each
myHash.each{|item|..} is returning you array object for item iterative variable like the following :--
[:company_name, "MyCompany"]
[:street, "Mainstreet"]
[:postcode, "1234"]
[:city, "MyCity"]
[:free_seats, "3"]
You should do this:--
def format
output = Hash.new
myHash.each do |k, v|
output[k] = cleanup(v)
end
output
end
Ive come across this many times in my work, an easy work around that I found is to ask if the array element is a Hash by class.
if i.class == Hash
notation like i[:label] will work in this block and not throw that error
end