How do I parse JSON with Ruby on Rails

Question

I m looking for a simple way to parse JSON  extract a value and write it into a database in Rails   Specifically what I m looking for  is a way to extract shortUrl from the JSON returned from the bit ly API         errorCode   0     errorMessage          results            http   www foo com                 hash    e5TEd           shortKeywordUrl               shortUrl    http   bit ly 1a0p8G           userHash    1a0p8G                statusCode    OK      And then take that shortUrl and write it into an ActiveRecord object associated with the long URL   This is one of those things that I can think through entirely in concept and when I sit down to execute I realize I ve got a lot to learn

User · Answer

require  json  out JSON parse input    This will return a Hash

User · Answer

Here s what I would do   json       errorCode   0   errorMessage          results      http   www foo com      hash     e5TEd     shortKeywordUrl          shortUrl     http   b i t ly 1a0p8G     userHash     1a0p8G       statusCode     OK      hash   JSON parse json  results   hash  results    If you know the source url then you can use   source url    http   www foo com  to sym  results fetch source url   shortUrl    gt   http   b i t ly 1a0p8G    If you don t know the key for the source url you can do the following   results fetch results keys 0    shortUrl    gt   http   b i t ly 1a0p8G    If you re not wanting to lookup keys using symbols  you can convert the keys in the hash to strings   results   json  results  stringify keys  results fetch results keys 0    shortUrl     gt   http   b i t ly 1a0p8G    If you re concerned the JSON structure might change you could build a simple JSON Schema and validate the JSON before attempting to access keys  This would provide a guard   NOTE  Had to mangle the bit ly url because of posting rules

User · Answer

require  json   hash   JSON parse string   work with the hash and do what you want to do

User · Answer

This can be done as below  just need to use JSON parse  then you can traverse through it normally with indices        ideally not really needed  but in case if JSON parse is not identifiable in your module   require  json    Assuming data from bitly api is stored in json data here  json data         errorCode   0     errorMessage          results            http   www foo com                 hash    e5TEd           shortKeywordUrl               shortUrl    http   whateverurl           userHash    1a0p8G                statusCode    OK      final data   JSON parse json data  puts final data  results    http   www foo com    shortUrl

User · Answer

Parsing JSON in Rails is quite straightforward   parsed json   ActiveSupport  JSON decode your json string    Let s suppose  the object you want to associate the shortUrl with is a Site object  which has two attributes - short url and long url  Than  to get the shortUrl and associate it with  the appropriate Site object  you can do something like   parsed json  results   each do  longUrl  convertedUrl    site   Site find by long url longUrl    site short url   convertedUrl  shortUrl     site save end

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This answer is quite old  pguardiario s got it   One site to check out is JSON implementation for Ruby  This site offers a gem you can install for a much faster C extension variant   With the benchmarks given their documentation page they claim that it is 21 500x faster than ActiveSupport  JSON decode  The code would be the same as Milan Novota s answer with this gem  but the parsing would just be   parsed json   JSON your json string

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These answers are a bit dated  Therefore I give you   hash   JSON parse string   Rails should automagically load the json module for you  so you don t need  to add require  json

User · Answer

The Oj gem  https   github com ohler55 oj  should work  It s simple and fast   http   www ohler com oj  Simple JSON Writing and Parsing Example  require  oj   h      one    gt  1   array    gt    true  false     json   Oj dump h     json            one  1       array          true        false            h2   Oj load json  puts  Same    h    h2     true   The Oj gem won t work for JRuby  For JRuby this  https   github com ralfstx minimal-json  or this  https   github com clojure data json  may be good options

User · Answer

Here is an update for 2013   Ruby  Ruby 1 9 has a default JSON gem with C extensions  You can use it with  require  json  JSON parse      x    y         gt    x   gt  y     The parse  variant can be used for safe sources  There are also other gems  which may be faster than the default implementation  Please refer to multi json for the list   Rails  Modern versions of Rails use multi json  a gem that automatically uses the fastest JSON gem available  Thus  the recommended way is to use  object   ActiveSupport  JSON decode json string   Please refer to ActiveSupport  JSON for more information  In particular  the important line in the method source is  data   MultiJson load json  options    Then in your Gemfile  include the gems you want to use  For example   group  production do   gem  oj  end

User · Answer

Ruby s bundled JSON is capable of exhibiting a bit of magic on its own    If you have a string containing JSON serialized data that you want to parse   JSON string to parse    JSON will look at the parameter  see it s a String and try decoding it   Similarly  if you have a hash or array you want serialized  use   JSON array of values    Or   JSON hash of values    And JSON will serialize it  You can also use the to json method if you want to avoid the visual similarity of the    method    Here are some examples   hash of values     foo    gt  1   bar    gt  2  array of values    hash of values   JSON hash of values       gt      foo   1   bar   2    JSON array of values       gt       foo   1   bar   2     string to parse   array of values to json JSON string to parse      gt     foo   gt 1   bar   gt 2     If you root around in JSON you might notice it s a subset of YAML  and  actually the YAML parser is what s handling JSON  You can do this too   require  yaml   YAML load string to parse      gt     foo   gt 1   bar   gt 2     If your app is parsing both YAML and JSON  you can let YAML handle both flavors of serialized data

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RUBY is case sensitive   require  json    json must be lower case  JSON parse  lt json object gt       for example   JSON parse response body    JSON must be all upper-case

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You can try something like this   def details to json      id                      gt  self id      credit period type      gt  self credit period type     credit payment period   gt  self credit payment period      to json end

[ruby-on-rails] How do I parse JSON with Ruby on Rails?

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