# DifferEcto [![Hex Version](https://img.shields.io/hexpm/v/differ_ecto.svg)](https://hex.pm/packages/differ_ecto) [![docs](https://img.shields.io/badge/docs-hexpm-blue.svg)](https://hexdocs.pm/differ_ecto/) [![Coverage Status](https://coveralls.io/repos/github/DanilaMihailov/differ_ecto/badge.svg?branch=master)](https://coveralls.io/github/DanilaMihailov/differ_ecto?branch=master)


`Ecto.Type` for `Differ` (and some helpers)

## Installation

The package can be installed
by adding `differ_ecto` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:differ_ecto, "~> 0.1.0"}
  ]
end
```

## Documentation

Documentation can be found at [https://hexdocs.pm/differ_ecto](https://hexdocs.pm/differ_ecto).


## Usage

You can use json array to store diffs like this

```elixir
defmodule Example do
  use Ecto.Schema
  # gives us Diffable, Patchable and Diff
  use DifferEcto

  # we have to skip :diffs field
  # skip timestamps as well
  @derive [{Diffable, skip: [:updated_at, :diffs]}, Patchable]
  schema "example" do
    field :body, :string
    field :title, :string
    # we want to store list of diffs in document
    field :diffs, {:array, Diff}, default: []
    timestamps()
  end
end

```

then when you do updates, you need to calculate diffs

```elixir
  def update(%Example{} = ex, attrs) do
    import Ecto.Changeset
    ex
    |> Example.changeset(attrs)
    |> Repo.update()
    |> case do
      # after successful update run diff
      {:ok, new_ex} ->
        diff = DifferEcto.diff(ex, new_ex)
        new_diffs = [diff | List.wrap(ex.diffs)]

        # save diff to list of diffs
        new_ex 
        |> cast(%{diffs: new_diffs}, [:diffs])
        |> Repo.update()
      val ->
        val
    end
```