Module: Plutonium::Positioning::MigrationHelpers

Defined in:
lib/plutonium/positioning.rb

Overview

Migration helper that adds a position column pre-tuned for fractional ordering. Mixed into ActiveRecord's table-definition classes by the railtie, so it is available in both create_table and change_table:

create_table :tasks do |t|
t.position                # decimal :position, precision: 16, scale: 8
t.position :sort_order    # custom column name
t.position index: true    # also add a single-column index
end

change_table :tasks do |t|
t.position
end

The precision/scale give midpoints ample headroom over the rebalance threshold (EPSILON = 1e-6) — a too-small scale lets the last subdivision round to a neighbor. Pass precision:/scale: to override.

Constant Summary collapse

DEFAULT_PRECISION = 
16
DEFAULT_SCALE = 
8

Instance Method Summary collapse

Instance Method Details

#position(name = :position, **options) ⇒ Object 



141
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# File 'lib/plutonium/positioning.rb', line 141

def position(name = :position, **options)
  column name, :decimal, precision: DEFAULT_PRECISION, scale: DEFAULT_SCALE, **options
end