Ruby - Append Data to Existing JSON

How do I append/add data to an JSON file with Ruby

Of course, simply joining two JSON strings together don't work and would result in an invalid JSON. In your example, the hash you try to add would not end up in the array but behind.

The correct way is to read the existing JSON file and parse it into a RUBY data structure and add the new hash in Ruby to the array before writing everything back to JSON.

require 'json'

filename = '/root/Desktop/jsonDatabase.json'

hash = { "first_name" => "john", "last_name" => "doe" }

array = JSON.parse(File.read(filename)
array << hash

File.open(filename, 'w') do |f|
  f.write(JSON.pretty_generate(array))
end

Append new values to an existing JSON array in ruby

In @scenario you have Array object, so if you wanna to add new hash inside this Array, just use Array#<< method like this.

Because the Array is object, you can add data inside this object.

new_scenario = {
  "ScenarioNumber" => 2,
  "ScenarioName" => "SC2",
  "ScenarioDescription" => "Desc",
  "ScExecutionStatus" => "Execution Complete",
  "ScenarioStatus" => "In-Complete",
  "ScenarioSeverity" => false,
  "TestCase" => [
    {
      "TestCaseNumber" => 1,
      "TestCaseName" => "Some Name ",
      "TcExecutionStatus" => "Execution Error",
      "TcStatus" => "NA",
      "TcSeverity" => "NA"
    }
  ]
}

@scenario << new_scenario

@template_file now include new_scenario

Ruby - Append data to existing JSON

You can use Array#push like this:

test = {
  :provisioningState=>"Succeeded",
  :resourceGuid=>"test",    
  :securityRules=>[
    {:name=>"SSH", :id=>"SSH", :etag=>"18",:type=>"Microsoft/securityRules", :properties=>{}}
  ]
}
new_rule = {
  :name => 'rule_2',
  :properties => {
    :protocol          => 'TCP',
    :sourceAddressPrefix => '*',
    :destinationAddressPrefix => '*',
    :access => 'Allow',
    :destinationPortRange => '22',
    :sourcePortRange => '*',
    :priority => '301',
    :direction => 'Inbound',
  }
}

test[:securityRules].push(new_rule)
test
# {
#   :provisioningState=>"Succeeded",
#   :resourceGuid=>"test",
#   :securityRules=> [
#     {:name=>"SSH", :id=>"SSH", :etag=>"18", :type=>"Microsoft/securityRules", :properties=>{}},
#     {:name=>"rule_2",:properties=>{:protocol=>"TCP",:sourceAddressPrefix=>"*",:destinationAddressPrefix=>"*",:access=>"Allow",:destinationPortRange=>"22",:sourcePortRange=>"*",:priori# ty=>"301",:direction=>"Inbound"}}
#   ]
# }

Appending the data in JSON file using Ruby

Uri Agassi's code is perfect, but I thought to explain what went wrong in the OP code.

The Hash[] expects an array of key, value pairs (either as separate arguments or an array of arrays):

Hash[:a, 1, :b, 2]        # => {:a=>1, :b=>2}
Hash[[[:a,1], [:b,2]]]    # => {:a=>1, :b=>2}

But the original JSON contained Array of Hashes which gets parsed into corresponding Ruby objects as in the simplified case:

[{:a => 1}, {:b => 2}]

When you use the Ruby splat operator * on the above array:

Hash[ *[{:a => 1}, {:b => 2}] ]

You efectively provide separate hashes as a key-value pair to the Hash constructor:

Hash[ {:a => 1}, {:b => 2} ]  # => {{:a=>1} => {:b=>2}}

So, essentially, you got what you asked for: you turned a array of hashes into a hash of hashes and then you added that to a blank array and topped up with another hash.

Correct solution

Just to make the original code work with minimal changes (but still take a look at Uri's solution):

tempHash = {"Group_Name" => @GroupName, "Group_Logo_Code" => @GroupLogoCode }

json = File.read('public/group.json')
secondJsonArray = JSON.parse(json)

secondJsonArray << tempHash

File.open("public/group.json","w") do |f|
  f.puts JSON.pretty_generate(secondJsonArray)
end

Add values to Ruby JSON Object

You could try this

json = { "data" => [
         {"name" => "A", "available" => "1"},
         {"name" => "B", "available" => "0"}
       ]}
json["data"].push({"name" => "C", "available" => "1"})

Ruby cant append to JSON file

rb_hash["searchExamples"] is a hash and as @axiac said there is no << method on Hash class in ruby. Use Hash#merge to concatenate two hashes:

json = File.read(File.join( File.dirname(__FILE__),"configs/#{enviroment}.json"))

rb_hash = JSON.parse(json);
rb_hash["searchExamples"] = rb_hash["searchExamples"].merge({ name: "John", long: 20, lat: 45 })
# or rb_hash["searchExamples"].merge!({ name: "John", long: 20, lat: 45 })

File.write(File.join( File.dirname(__FILE__),"configs/#{enviroment}.json"), rb_hash.to_json)

Also you might want to use pretty generate gems like NeatJSON or JSON#pretty_generate for better json output in your file

Appending to JSON array in Ruby

First convert the JSON to a Ruby hash this way:

require 'json'
rb_hash = JSON.parse('<your json>');
rb_hash["data"] << { name: "John", long: 20, lat: 45 }

rb_hash.to_json

How to add new key/value pair to existing JSON object in Ruby

How could I append a new key/value pair to existing JSON object in Ruby?

If you want to add it to an existing file then you should read the JSON first, extract data from it, then add a new hash to an array.

Maybe something like this will solve your problem:

def create_book(name, author)
  tempHash = {
  SecureRandom.uuid => {
    "name" => name,
    "author" => author
    }
  }

  data_from_json = JSON[File.read("./books/book.json")]
  data_from_json = [data_from_json] if data_from_json.class != Array
  File.open("./books/book.json","w") do |f|
    f.write(JSON.pretty_generate(data_from_json << tempHash))
  end
end

There are also some other ways like manipulating the JSON as a common string but for safety you should extract the data and then create a new JSON file.

how to append data to json in ruby/rails?

item = Item.find(params[:id])
item["message"] = "it works"
render :json => item.to_json

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