json-path-builder

JsonPathBuilder

Aims to provide a declarative JSON based mapper

Console

run irb -r ./dev/setup for an interactive prompt.

Installation

Add this line to your application's Gemfile:

gem 'json-path-builder'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install json-path-builder

JsonPath::Builder

.build_for

maps input based fields to be mapped via .from method

For advance usage check out .from documentation

input = { key: "some-value" }
JsonPath::Builder.new.from(:key, to: :another_key).build_for(input) 
#=> {:another_key=>"some-value"}

.from

defines the json path(s) to locate the value(s) to be mapped for each field

Required arguments:

• json_path ~ JSON path supporting dot notation which contains the value(s) relating to the field to be mapped e.g. account.profile.name

Optional arguments:

• to: ~ field name for mapped value (defaults to json_path)
• transform:
  • can be one of the following
    • Proc e.g. ->(val) { val.to_s.upcase } to convert value located at json_path to uppercase
    • Built in Transforms
      • :iso8601 e.g. Date.new(2022,1,1) => 2022-01-01
      • :date e.g. 2022-01-01 => <Date Sat, 01 Jan 2022>
  • defaults - (Hash) e.g. {user_id: 1}
  • fallback - (Proc) used when mapped value is blank

Example:

# Example 1 - Mapping subset of fields
input = { key: "some-value", other_key: "some-other-value", list: %w[some-list-value-1 some-list-value-2] }.as_json
builder = JsonPath::Builder.new
builder.from(:key)
builder.from(:other_key)
builder.build_for(input) #=> {:key=>"some-value", :other_key=>"some-other-value"}

# Example 2 - Mapping nested field to non nested
input = { profile: {email: '[e-mail]'} }.as_json
JsonPath::Builder.new.from('profile.email', to: :email).build_for(input) #=> {:email=>"[e-mail]"}

# Example 3 - mapping field to another field name
input = { key: "some-value" }
JsonPath::Builder.new.from(:key, to: :another_key).build_for(input) #=> {:another_key=>"some-value"}

# Example 4 - mapping field to nested field
input = { key: "some-value" }
JsonPath::Builder.new.from(:key, to: "root.key").build_for(input) #=> {:root=>{:key=>"some-value"}}

# Example 5 - transforming value to uppercase
input = { key: "some-value" }
transform = ->(val) { val.to_s.upcase }
JsonPath::Builder.new.from(:key, transform: transform).build_for(input) #=> {:key=>"SOME-VALUE"}

# Example 6 - transforming value to iso8601 format
input = { created_at: Date.new(2022,1,2) }
transform = :iso8601
JsonPath::Builder.new.from(:created_at, transform: transform).build_for(input) #=> {:created_at=>"2022-01-02"}

# Example 6 - transforming value to iso8601 format
input = { created_at: '2023-02-27 16:24:02' }
transform = :date
JsonPath::Builder.new.from(:created_at, transform: transform).build_for(input) #=> {:created_at=><Date Sat, 01 Jan 2022>}

# Example 7 - fallback when value to be mapped is `nil` or not present
input = { }
fallback = -> { Time.now }
JsonPath::Builder.new.from(:created_at, fallback: fallback).build_for(input)
# => {:created_at=> <Time 2023-02-27 16:36:44.068037 -0700>}

.from_each

similar to .from but for mapping list items

Example:

input = { list: %w[some-list-value-1 some-list-value-2] }.as_json
builder = JsonPath::Builder.new
transform = proc { |val| val.upcase }
builder.from_each(:list, to: :keys, transform: transform)
builder.build_for(input) #=> {:keys=>["SOME-LIST-VALUE-1", "SOME-LIST-VALUE-2"]}

.within

Adds the ability to provide a scope based on dot notation

Example:

input = { root: { deep: { profile: { email: '[e-mail]', uid: 1 } } } }.as_json
builder = JsonPath::Builder.new
builder.within('root.deep.profile') do |b|
  b.from(:email)
  b.from(:uid, to: :user_id)
end

builder.build_for(input) #=> {:email=>"[e-mail]", :user_id=>1}

#with_wrapped_data_class

Supports wrapping mapped values with a custom class that must act like a hash i.e. implements SimpleDelegator

Example:

input = { profile: { email: '[e-mail]', uid: 1 } }.as_json
builder = JsonPath::Builder.new
wrapped_data_class = Class.new(SimpleDelegator) do
  def user
    User.find_by(email: self[:email])
  end
end
builder.with_wrapped_data_class(wrapped_data_class)
transform = proc { |email, path_context| }
builder.from('profile.email', to: :user_id, transform: transform)


email = '[e-mail]'
user_id = 123
input = { profile: { email: email } }.as_json
user = OpenStruct.new(id: user_id)
user_repo = OpenStruct.new(find_by: -> (_email) { user })

wrapped_data_class = Class.new(SimpleDelegator) do
  class << self
    attr_accessor :user_repo
  end

  def user
    self.class.user_repo.find_by.call(email: self.dig('profile', 'email'))
  end
end
wrapped_data_class.user_repo = user_repo

builder = JsonPath::Builder.new
builder.with_wrapped_data_class(wrapped_data_class)
transform = proc do |_email, path_context|
  path_context.wrapped_source_data.user.id
end

builder.from('profile.email', to: :user_id, transform: transform)
builder.build_for(input) #=> {:user_id=>123}

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/json-path-builder. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the JsonPathBuilder project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.