So I am iterating through a set of data and building a hash from it:
clean_response = Array.new
response.each_with_index do |h, idx|
clean_response <<
{
:lat => h["location"]["latitude"],
:lg => h["location"]["longitude"],
:place => h["location"]["name"],
#This grabs the entire hash at "location" because we are wanting all of that data
:profile_picture => h["user"]["profile_picture"],
:hash_tags => h["tags"],
:username => h["user"]["username"],
:fullname => h["user"]["full_name"],
:created_time => (Time.at(h["created_time"].to_i)).to_s,
:image => h["images"]["low_resolution"]["url"] # we can replace this with whichever resolution.
}
end
Which return an array of hashes like so:
[{:lat=>40.7486382,
:lg=>-73.9487686,
:place=>"The Cliffs at LIC",
:profile_picture=>"http://scontent.cdninstagram.com/hphotos-xaf1/t51.2885-19/s150x150/12104940_1653775014895036_286845624_a.jpg",
:hash_tags=>["bouldering"],
:username=>"denim_climber",
:fullname=>"DenimClimber",
:created_time=>2015-10-13 22:58:09 -0400,
:image=>"https://scontent.cdninstagram.com/hphotos-xaf1/t51.2885-15/s320x320/e35/11856571_1062082890510188_611068928_n.jpg"},
{:lat=>40.7459602,
:lg=>-73.9574966,
:place=>"SHI",
:profile_picture=>"http://scontent.cdninstagram.com/hphotos-xaf1/t51.2885-19/11348212_1453525204954535_631200718_a.jpg",
:hash_tags=>["cousins", "suchafunmoment", "johnlennonstyle"],
:username=>"xiomirb",
:fullname=>"Xiomi",
:created_time=>2015-10-13 22:57:21 -0400,
:image=>"https://scontent.cdninstagram.com/hphotos-xaf1/t51.2885-15/s320x320/e35/11375290_1688934151392424_2009781937_n.jpg"}]
I'd like to convert this data to json and then serve it to a specific view.
How can I convert this? I tried the .to_json method but it doesn't return a well formatted one since my UI isn't binding to the data.
You can convert a Ruby hash into JSON using to_json:
require 'json'
your_hash.to_json # gives you a JSON object
But, in your case the data is an array of hashes, but NOT a hash. So, your to_json would not work.
I am not quite sure how you want to do this, but one possibility is to loop through the array of hashes, get each hash and convert that to a JSON object using to_json call (like shown above) and build a new array of JSON objects. This way, you can build an array of JSON objects from an array of hashes.
array_of_json = []
# loop through the array of hashes
clean_response.each do |hash|
array_of_json << hash.to_json
end
array_of_json # array of JSON objects
If by "serve it to a specific view" you mean pass it to a .haml or .erb template, you can pass the array of hashes as is. Both haml and erb will allow you to iterate over the array, and even the hash if you want.
If you mean you want to hand a json string to the browser, #to_json should work fine. Other options are jbuilder or oat when you want to refine what is sent, but to_json should "serve" you well!
Related
I save an array of strings to my rails database, but when I go to use it in the view, I believe it is printing the string definition of the array. Am I dealing with JSON here? (aka when it saves to the database is it just an array wrapped in a string?)
How do I have it so that in my view, it simply displays the items?
<%= record.items %>
displays inside my html tag:
["item1", "item2", "item3"]
I tried iterating through record.items.each do |item| but that did not work.
If you're saving an "exact" array as a String, then Array#each won't work, because isn't a method in the String class.
Maybe isn't the best option, but you could use JSON.parse and this way get your array and be able to iterate over each object inside:
require 'json'
str = '["item1", "item2", "item3"]'
JSON.parse(str).each { |item| p item }
# "item1"
# "item2"
# "item3"
In order this work your string must be an array, in your example the second item is missing its double quote.
You could consider working with serialization or array data types depending on you current database.
A better approach to your issue is to serialize your items column. I think by default it's Array but you can use Hash or JSON.
class Record < ActiveRecord::Base
serialize :items
end
Calling record.items returns the data exactly the way you need. If you go with this you'll have to update your old records to support it.
I have a controller returning a json structure like so:
def show
# .......
o_json = deep_object_1_to_json(o)
render :json => o_json
end
private
def deep_object_1_to_json(o)
o.to_json(
:include => {....})
end
Now I need to extend it to return 2 objects. However the obvious solution is giving me problems:
def show
# .......
o1_json = deep_object_1_to_json(o)
o2_json = deep_object_2_to_json(o)
render :json =>
{
:object_1 => o1_json,
:object_2 => o2_json
}
end
This returns a json object with 2 strings of escaped json data!
The deep_object_2_to_json functions already have several layers of nested includes so I would rather not have to refactor these into a single function. Is there a way to make this easily extendable to add more objects in the future without the double escaping problem above?
Thanks for any pointers.
Sounds like you should be constructing something upon which to_json can easily be called.
The obvious candidate for active record objects is as_json. This does everything that to_json does (include the :include option and so on) except actually turning the object into json. Instead you get back a ruby hash which you can manipulate as you want and then call to_json. For example you could do
render :json => {
:o1 => object1.as_json(:include => :blah),
:o2 => object2.as_json(:include => :blah)
}
Your controller shouldn't be serializing the object as JSON until right before it hands it off to be rendered.
In other words deep_object_1_to_json should just be deep_object_1. Then you can package both return values into an array or hash and render the as JSON.
def show
# .......
o1 = deep_object_1(o)
o2 = deep_object_2(o)
render :json =>
{
:object_1 => o1,
:object_2 => o2
}
end
It might be a pain to change it now, but for the future of your system, you really ought to be doing it this way. JSON is just a format for sending objects over the wire or to disk; none of your code should have any references whatsoever to JSON unless it is passing it off to be rendered.
If you can refactor your class to return it's JSON via the to_json method, you can simply stick two or more objects into an array and call to_json on the array:
1.9.3-p125 :001 > require 'json'
=> true
1.9.3-p125 :002 > [{foo: "bar"}, {bar: "foo"}].to_json
=> "[{\"foo\":\"bar\"},{\"bar\":\"foo\"}]"
Example:
def to_json
super(include: [:some_association])
end
I'm using json gem in ruby..,My ruby code is here..,
require 'json'
json = JSON.generate [1, 2, [{"pi" => 3.141}, {"integer" => 1234567890}], {"subject" => "Mathematics"}, {"Float"=> 1.324343}, {"number"=> 232132435}]
generator = JSON.parse json
puts generator[2][1]
My key-value pair is working fine.But, I'm trying to print only the key not an value from index[2] such as either an "integer" or "pi".
Is it possible..?
In your case generator[2][1] is a Hash {"integer"=>1234567890}. In order to get all keys from hash you can use Hash#keys method, and then take first (as far as it is the only key in the hash)
generator[2][1].keys.first # => "integer"
You can learn more about Hash methods in this documentation.
Your data structure at generator[2] looks strange, maybe you better use a single Hash for such casese:
{"pi" => 3.141, "integer" => 1234567890} # etc...
I am new to Ruby, and I am having some problems with hashes.
I have XML returned from the YouTube API that I converted into a hash. Here is the hash returned by Hash.from_xml(): http://pastebin.com/9xxE6iXU
I am trying to grab specific elements from the hash for each result, such as the title, link, author, etc. Whenever I try to loop through the hash or grab a specific element, I receive a "can't convert String into Integer" error.
Here is the code I am using for the loop:
#data["feed"]["entry"]["title"].each do |key, value|
"<p>"+key+" "+value+"</p>"
end
I have also tried grabbing specific elements, such as #data["feed"]["entry"]["title"][0].
How do I loop through the hash and grab specific elements out?
That's happening because #data["feed"]["entry"] is array of hashes:
puts #data["feed"]["entry"].class # => Array
Each element-hash inside this array has "id", "category", "title" etc. values.
For grabbing each title try to use following snippet:
#data["feed"]["entry"].each do |entry|
puts entry["title"]
end
# => "TABE test adult basic education"
"WhatCollegesHopeYouWon'tFindOutAboutACTSATTestPrep..."
....
Lets say I have this Hash:
{
:info => [
{
:from => "Ryan Bates",
:message => "sup bra",
:time => "04:35 AM"
}
]
}
I can call the info array by doing hash[:info].
Now when I turn this into JSON (JSON.generate), and then parse it (JSON.parse), I get this hash:
{
"info" => [
{
"from" => "Ryan Bates",
"message" => "sup bra",
"time" => "04:35 AM"
}
]
}
Now if I use hash[:info] it returns nil, but not if I use hash["info"].
Why is this? And is there anyway to fix this incompatibility (besides using string keys from the start)?
The JSON generator converts symbols to strings because JSON does not support symbols. Since JSON keys are all strings, parsing a JSON document will produce a Ruby hash with string keys by default.
You can tell the parser to use symbols instead of strings by using the symbolize_names option.
Example:
original_hash = {:info => [{:from => "Ryan Bates", :message => "sup bra", :time => "04:35 AM"}]}
serialized = JSON.generate(original_hash)
new_hash = JSON.parse(serialized, {:symbolize_names => true})
new_hash[:info]
#=> [{:from=>"Ryan Bates", :message=>"sup bra", :time=>"04:35 AM"}]
Reference: http://www.ruby-doc.org/stdlib-1.9.3/libdoc/json/rdoc/JSON.html#method-i-parse
In short, no. Think about it this way, storing symbols in JSON is the same as storing strings in JSON. So you cannot possibly distinguish between the two when it comes to parsing the JSON string. You can of course convert the string keys back into symbols, or in fact even build a class to interact with JSON which does this automagically, but I would recommend just using strings.
But, just for the sake of it, here are the answers to this question the previous times it's been asked:
what is the best way to convert a json formatted key value pair to ruby hash with symbol as key?
ActiveSupport::JSON decode hash losing symbols
Or perhaps a HashWithIndifferentAccess
I solved my similar issue with calling the with_indifferent_access method on it
Here I have a json string and we can assign it to variable s
s = "{\"foo\":{\"bar\":\"cool\"}}"
So now I can parse the data with the JSON class and assign it to h
h = JSON.parse(s).with_indifferent_access
This will produce a hash that can accept a string or a symbol as the key
h[:foo]["bar"]
#=> "cool"
Use ActiveSupport::JSON.decode, it will allow you to swap json parsers easier
Use ActiveSupport::JSON.decode(my_json, symbolize_names: true)
This will recursively symbolize all keys in the hash.
(confirmed on ruby 2.0)
It's possible to modify all the keys in a hash to convert them from a string to a symbol:
symbol_hash = Hash[obj.map{ |k,v| [k.to_sym, v] }]
puts symbol_hash[:info]
# => {"from"=>"Ryan Bates", "message"=>"sup bra", "time"=>"04:35 AM"}
Unfortunately that doesn't work for the hash nested inside the array. You can, however, write a little recursive method that converts all hash keys:
def symbolize_keys(obj)
#puts obj.class # Useful for debugging
return obj.collect { |a| symbolize_keys(a) } if obj.is_a?(Array)
return obj unless obj.is_a?(Hash)
return Hash[obj.map{ |k,v| [k.to_sym, symbolize_keys(v)] }]
end
symbol_hash = symbolize_keys(hash)
puts symbol_hash[:info]
# => {:from=>"Ryan Bates", :message=>"sup bra", :time=>"04:35 AM"}
You can't use that option like this
ActiveSupport::JSON.decode(str_json, symbolize_names: true)
In Rails 4.1 or later, ActiveSupport::JSON.decode no longer accepts
an options hash for MultiJSON. MultiJSON reached its end of life and
has been removed.
You can use symbolize_keys to handle it.
Warning: It works only for JSON strings parsed to hash.
ActiveSupport::JSON.decode(str_json).symbolize_keys