Module: Exwiw::DefaultMask

Defined in:
lib/exwiw/default_mask.rb

Overview

The replace_with value safe mode attaches to a newly discovered column.

Only types a constant can safely stand in for are masked: a default the column cannot hold would fail the restore the dump feeds, which is worse than exporting the column while its needs_mask_decision flag keeps the change from being merged.

Constant Summary collapse

FIXED_DATE = 
"2000-01-01"
FIXED_TIME = 
"2000-01-01 00:00:00"
EMPTY_JSON = 
"{}"
JSON_TYPES = 
%i[json jsonb].freeze
MIN_TEXT_LIMIT =

Skip the mask when the column is too short to hold masked-<primary key> for a realistic key; the rendered length is only known per row at dump time.

20
MIN_EMAIL_LIMIT = 
40

Class Method Summary collapse

Class Method Details

.constant_mask(type, column_default) ⇒ Object

The column's own default wins over the per-type constant: it is a value the column provably holds and the one the application treats as neutral, so masking a default: true flag does not turn the feature off for every row. A default the database computes (now()) arrives as nil and falls through.



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# File 'lib/exwiw/default_mask.rb', line 48

def constant_mask(type, column_default)
  from_default = default_value(type, column_default)
  return from_default unless from_default.nil?

  case type
  when :integer, :decimal, :float then 0
  when :boolean then false
  when :date then FIXED_DATE
  when :datetime, :timestamp, :time then FIXED_TIME
  when :json, :jsonb then EMPTY_JSON
  end
end

.default_value(type, value) ⇒ Object

The default as a mask value, or nil when it cannot be one. A JSON column's default is serialized as JSON whatever Ruby class it arrives as, so a string default keeps its quoting. Anything whose JSON contains an object is rejected rather than mis-parsed, so an array of objects falls back to the empty-JSON constant too.



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# File 'lib/exwiw/default_mask.rb', line 66

def default_value(type, value)
  return nil if value.nil?

  mask = JSON_TYPES.include?(type) ? value.to_json : scalar_default(value)
  return nil if mask.is_a?(String) && mask.match?(MaskValue::PLACEHOLDER)

  mask
end

.for(name:, type:, limit:, primary_key:, array: false, unique: false, column_default: nil) ⇒ Object

The default mask for a column, or nil when no safe constant fits it. primary_key is what keeps a text mask unique per row, so without one text is left unmasked too. Under a unique index (unique) only a mask that varies per row is allowed, or every row would collide on restore.



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# File 'lib/exwiw/default_mask.rb', line 29

def for(name:, type:, limit:, primary_key:, array: false, unique: false, column_default: nil)
  return nil if array

  mask =
    case type
    when :string, :text then text_mask(name, limit, primary_key)
    else constant_mask(type, column_default)
    end

  return nil if mask.nil?
  return nil if unique && !varies_per_row?(mask, primary_key)

  mask
end

.scalar_default(value) ⇒ Object 



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# File 'lib/exwiw/default_mask.rb', line 75

def scalar_default(value)
  case value
  when nil then nil
  when true, false, Integer, Float, String then value
  when Numeric then value.to_f
  when Time, DateTime then value.strftime("%Y-%m-%d %H:%M:%S")
  when Date then value.strftime("%Y-%m-%d")
  when Hash, Array then value.to_json
  end
end

.text_mask(name, limit, primary_key) ⇒ Object 



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# File 'lib/exwiw/default_mask.rb', line 86

def text_mask(name, limit, primary_key)
  return nil if primary_key.nil?

  if name.to_s.include?("mail")
    return nil if limit && limit < MIN_EMAIL_LIMIT

    "masked-{#{primary_key}}@example.com"
  else
    return nil if limit && limit < MIN_TEXT_LIMIT

    "masked-{#{primary_key}}"
  end
end

.varies_per_row?(mask, primary_key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/exwiw/default_mask.rb', line 100

def varies_per_row?(mask, primary_key)
  mask.is_a?(String) && mask.include?("{#{primary_key}}")
end