Ruby JSON

Ruby JSON

JSON (JavaScript Object Notation) is a lightweight data-interchange format that's easy for humans to read and write and easy for machines to parse and generate. Ruby includes a library to parse JSON.

Here is a tutorial on how to work with JSON in Ruby:

1. Parsing JSON

First, you need to require the json library:

require 'json'

Then you can parse a JSON string like this:

json_string = '{"name":"John", "age":30, "city":"New York"}' parsed = JSON.parse(json_string) puts parsed["name"] # Outputs: John

JSON.parse takes a JSON string and converts it into a Ruby hash.

2. Generating JSON

You can also generate a JSON string from a Ruby hash like this:

require 'json' hash = {"name" => "John", "age" => 30, "city" => "New York"} json_string = JSON.generate(hash) puts json_string # Outputs: {"name":"John","age":30,"city":"New York"}

JSON.generate takes a Ruby hash and converts it into a JSON string.

3. Reading JSON from a File

You can read JSON from a file like this:

require 'json' file = File.read('input.json') data = JSON.parse(file) puts data["name"] # Outputs: John

4. Writing JSON to a File

Similarly, you can write JSON to a file like this:

require 'json' hash = {"name" => "John", "age" => 30, "city" => "New York"} File.open("output.json","w") do |f| f.write(JSON.pretty_generate(hash)) end

Here, JSON.pretty_generate is used instead of JSON.generate to format the JSON string in a more human-readable way.

Remember that JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. This makes it an ideal data-interchange language.

Examples

  1. Parsing JSON in Ruby: Ruby provides a built-in JSON module for parsing JSON strings.

    require 'json' json_string = '{"name": "John", "age": 30}' parsed_data = JSON.parse(json_string)

  2. Generating JSON in Ruby: Use the to_json method to convert Ruby objects to JSON format.

    data = { name: 'Jane', age: 25 } json_string = data.to_json

  3. Ruby JSON library: The JSON module is part of the Ruby standard library and handles JSON encoding and decoding.

    require 'json'

  4. Working with JSON objects in Ruby: Once parsed, JSON objects in Ruby are treated like regular hashes and arrays.

    puts parsed_data['name'] # Accessing JSON object properties

  5. Ruby JSON parse vs. load: Both JSON.parse and JSON.load can be used for parsing JSON, but load can handle additional options.

    parsed_data = JSON.parse(json_string) parsed_data = JSON.load(json_string)

  6. Serializing Ruby objects to JSON: Customize serialization using to_json and as_json methods.

    class Person attr_accessor :name, :age def as_json(options = {}) { name: name, age: age } end end person = Person.new(name: 'Alice', age: 28) json_string = person.to_json

  7. Deserializing JSON to Ruby objects: Implement a custom json_create method for deserialization.

    class Person def self.json_create(data) new(name: data['name'], age: data['age']) end end person = JSON.parse(json_string, object_class: Person)

  8. Handling JSON arrays in Ruby: JSON arrays can be parsed and manipulated like Ruby arrays.

    json_array = '[1, 2, 3]' array = JSON.parse(json_array)

  9. Ruby JSON pretty print: Use the JSON.pretty_generate method for human-readable JSON.

    data = { name: 'Bob', age: 35 } pretty_json = JSON.pretty_generate(data)

  10. JSON encoding and decoding in Ruby: Encoding and decoding are done with JSON.dump and JSON.load.

    encoded = JSON.dump(data) decoded = JSON.load(encoded)

  11. Reading JSON from a file in Ruby: Read JSON data from a file using File and JSON modules.

    require 'json' file_data = File.read('data.json') parsed_data = JSON.parse(file_data)

  12. Ruby JSON gem usage: The json gem provides additional features and optimizations for working with JSON.

    gem 'json', require: 'json'

  13. Ruby JSON API requests: Fetch and parse JSON data from an API using tools like Net::HTTP.

    require 'json' require 'net/http' uri = URI('https://api.example.com/data') response = Net::HTTP.get(uri) parsed_data = JSON.parse(response)

  14. Validating JSON in Ruby: Ruby's JSON::Validator can be used to validate JSON against a schema.

    require 'json' require 'json-schema' schema = { type: 'object', properties: { name: { type: 'string' }, age: { type: 'integer' } } } data = { name: 'John', age: 30 } JSON::Validator.validate!(schema, data)

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