Json Parser

This project allows for a quick hash / json data fetching in order to avoid code that tries to crawl through a hash and has to constantly check for nil values or missing keys

also, this concern, like openstruct, allow the json to be manipulated as an object, but avoids method missing by aways having the declarated methods, even if that means nil return

Json Parser is also usefull when you need keys case changed or data type cast

Getting started

Add JsonParser to your Gemfile and bundle install:

  gem 'json_parser'

Include in a class that you want to wrap a json/hash
```
class MyParser
include JsonParser
```
Declare the keys you want to crawl
```
class MyParser
include JsonParser
```

json_parse :id json_parse :name, :age, path: :person

attr_reader :json

def initialize(json = {}) @json = json end end


  and let it fetch values from your hash


  ```ruby
  object = MyParser.new(
    id: 10,
    age: 22
    person: {
      name: 'Robert',
      age: 22
    }
  )

  object.name
  #returns 'Robert'

this is usefull when trying to fetch data from hashes missing nodes

  MyParser.new.name
  #returns nil

fully customise the way you crawl / fetch the information with Options
Create custom typecast

Options

path: path where to find the sub hash that contains the key (empty by default)
json: method that contains the hash to be parsed (json by default)
full_path: full path to fetch the value (empty by default)
cached: indicator that once the value has been fetched, it should be cached (false by default)
class: class to be used when wrapping the final value
compact: indicator telling to ignore nil values inside array (false by default)
flatten: indicator telling that to flattern the resulting array (false by default)
after: name of a method to be called after with the resulting value
case: case of the keys from the json (camel by default)
type: Type that the value must be cast into (TypeCast)
default: Default value (prior to casting and wrapping, see Default)

TypeCast

The type casting, when the option type is passed, is done through the JsonParser::TypeCast which can be extended

module JsonParser::TypeCast
  def to_money_float(value)
    value.gsub(/\$ */, '').to_f
  end
end

class MyParser
  include JsonParser

  json_parse :total_money, full_path: 'accounts.balance', after: :sum,
                          cached: true, type: :money_float
  json_parse :total_owed, full_path: 'loans.value', after: :sum,
                          cached: true, type: :money_float

  attr_reader :json

  def initialize(json = {})
    @json = json
  end

  private

  #this method will receive the array of values resulting from the initial mapping
  def sum(balances)
    balances.sum if balances
  end
end

  object = MyParser.new(
    accounts: [
      { balance: '$ 1000.50', type: 'checking' },
      { balance: '$ 150.10', type: 'savings' },
      { balance: '$ -100.24', type: 'checking' }
    ],
    loans: [
      { value: '$ 300.50', bank: 'the_bank' },
      { value: '$ 150.10', type: 'the_other_bank' },
      { value: '$ 100.24', type: 'the_same_bank' }
    ]
  )

  object.balance
#returns 1050.36

Default

Default value returned before typecasting or class wrapping

class Star
  attr_reader :name

  def initialize(name:)
    @name = name
  end
end

class StarGazer
  include JsonParser

  json_parse :favorite_star, full_path: 'universe.star',
             default: { name: 'Sun' }, class: ::Star

  attr_reader :json

  def initialize(json = {})
    @json = json
  end
end

star_gazer = StarGazer.new

star_gazer.favorite_star.name
#returns "Sun"

star_gazer.favorite_star.class
#returns Star