Module DeepMerge
In: lib/deep_merge/rails_compat.rb
lib/deep_merge/deep_merge_hash.rb
lib/deep_merge/core.rb

Methods

Classes and Modules

Module DeepMerge::DeepMergeHash
Module DeepMerge::RailsCompat
Class DeepMerge::InvalidParameter

Constants

DEFAULT_FIELD_KNOCKOUT_PREFIX = '--'

Public Class methods

Deep Merge core documentation. deep_merge! method permits merging of arbitrary child elements. The two top level elements must be hashes. These hashes can contain unlimited (to stack limit) levels of child elements. These child elements to not have to be of the same types. Where child elements are of the same type, deep_merge will attempt to merge them together. Where child elements are not of the same type, deep_merge will skip or optionally overwrite the destination element with the contents of the source element at that level. So if you have two hashes like this:

  source = {:x => [1,2,3], :y => 2}
  dest =   {:x => [4,5,'6'], :y => [7,8,9]}
  dest.deep_merge!(source)
  Results: {:x => [1,2,3,4,5,'6'], :y => 2}

By default, "deep_merge!" will overwrite any unmergeables and merge everything else. To avoid this, use "deep_merge" (no bang/exclamation mark)

Options:

  Options are specified in the last parameter passed, which should be in hash format:
  hash.deep_merge!({:x => [1,2]}, {:knockout_prefix => '--'})
  :preserve_unmergeables  DEFAULT: false
     Set to true to skip any unmergeable elements from source
  :knockout_prefix        DEFAULT: nil
     Set to string value to signify prefix which deletes elements from existing element
  :sort_merged_arrays     DEFAULT: false
     Set to true to sort all arrays that are merged together
  :unpack_arrays          DEFAULT: nil
     Set to string value to run "Array::join" then "String::split" against all arrays
  :merge_hash_arrays      DEFAULT: false
     Set to true to merge hashes within arrays
  :merge_debug            DEFAULT: false
     Set to true to get console output of merge process for debugging

Selected Options Details: :knockout_prefix => The purpose of this is to provide a way to remove elements

  from existing Hash by specifying them in a special way in incoming hash
   source = {:x => ['--1', '2']}
   dest   = {:x => ['1', '3']}
   dest.ko_deep_merge!(source)
   Results: {:x => ['2','3']}
  Additionally, if the knockout_prefix is passed alone as a string, it will cause
  the entire element to be removed:
   source = {:x => '--'}
   dest   = {:x => [1,2,3]}
   dest.ko_deep_merge!(source)
   Results: {:x => ""}

:unpack_arrays => The purpose of this is to permit compound elements to be passed

  in as strings and to be converted into discrete array elements
  irsource = {:x => ['1,2,3', '4']}
  dest   = {:x => ['5','6','7,8']}
  dest.deep_merge!(source, {:unpack_arrays => ','})
  Results: {:x => ['1','2','3','4','5','6','7','8'}
  Why: If receiving data from an HTML form, this makes it easy for a checkbox
   to pass multiple values from within a single HTML element

:merge_hash_arrays => merge hashes within arrays

  source = {:x => [{:y => 1}]}
  dest   = {:x => [{:z => 2}]}
  dest.deep_merge!(source, {:merge_hash_arrays => true})
  Results: {:x => [{:y => 1, :z => 2}]}

There are many tests for this library - and you can learn more about the features and usages of deep_merge! by just browsing the test examples

allows deep_merge! to uniformly handle overwriting of unmergeable entities

[Validate]