seanculver/ecto-ordered

Ecto extension for ordered models

EctoOrdered

Ecto extension to support ordered list items. Similar to acts_as_list, but for Ecto

It uses a rank column in the database to store the rank. This will contain non-consecutive integers so new records can be placed in between two old records and no updates to the old records are needed. The position field is therefore virtual. See: ranked-model

Add the latest stable release to your mix.exs file:

defp deps do
  [
    {:ecto_ordered, git: "https://github.com/maartenvanvliet/ecto-ordered", branch: "master"}
  ]
end

Examples

Global positioning

defmodule MyModel do
  use Ecto.Schema
  import Ecto.Changeset

  schema "ordered_list_item" do
    field :title,            :string
    field :position,         :integer, virtual: true
    field :rank,             :integer
    field :move,             :any, virtual: true
  end

  def changeset(model, params) do
    model
    |> cast(params, [:position, :title, :move])
    |> set_order(:position, :rank)
  end
end

Scoped positioning

defmodule MyModel do
  use Ecto.Schema
  import Ecto.Changeset

  schema "ordered_list_item" do
    field :title,            :string
    field :position,         :integer, virtual: true
    field :rank,             :integer
    field :move,             :any, virtual: true
    field :reference_id,     :integer
    field :scope             :integer
  end

  def changeset(model, params) do
    model
    |> cast(params, [:position, :title, :move, :reference_id])
    |> set_order(:position, :rank, :reference_id)
  end
end

Multi scoped positioning

Same as above but with a list for the scope in the changeset

  def changeset(model, params) do
    model
    |> cast(params, [:position, :title, :move, :reference_id])
    |> set_order(:position, :rank, [:reference_id, :scope])
  end