PaperTrail lets you record every change in your database in a separate database table called versions
. Library generates a new version record with associated data every time you run PaperTrail.insert/2
, PaperTrail.update/2
or PaperTrail.delete/2
functions. Simply these functions wrap your Repo insert, update or destroy actions in a database transaction, so if your database action fails you won't get a new version.
PaperTrail is assailed with hundreds of test assertions for each release. Data integrity is an important aim of this project, please refer to the strict_mode if you want to ensure data correctness and integrity of your versions. For simpler use cases the default mode of PaperTrail should suffice.
changeset = Post.changeset(%Post{}, %{
title: "Word on the street is Elixir got its own database versioning library",
content: "You should try it now!"
})
PaperTrail.insert(changeset)
# => on success:
# {:ok,
# %{model: %Post{__meta__: #Ecto.Schema.Metadata<:loaded, "posts">,
# title: "Word on the street is Elixir got its own database versioning library",
# content: "You should try it now!", id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 21:42:38]},
# version: %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "insert", id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# item_changes: %{title: "Word on the street is Elixir got its own database versioning library",
# content: "You should try it now!", id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 21:42:38]},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}}}
# => on error(it matches Repo.insert/2):
# {:error, Ecto.Changeset<action: :insert,
# changes: %{title: "Word on the street is Elixir got its own database versioning library", content: "You should try it now!"},
# errors: [content: {"is too short", []}], data: #Post<>,
# valid?: false>, %{}}
post = Repo.get!(Post, 1)
edit_changeset = Post.changeset(post, %{
title: "Elixir matures fast",
content: "Future is already here, Elixir is the next step!"
})
PaperTrail.update(edit_changeset)
# => on success:
# {:ok,
# %{model: %Post{__meta__: #Ecto.Schema.Metadata<:loaded, "posts">,
# title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!",
# id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 22:00:59]},
# version: %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "update", id: 2, inserted_at: ~N[2016-09-15 22:00:59],
# item_changes: %{title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!"},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil
# meta: nil}}}
# => on error(it matches Repo.update/2):
# {:error, Ecto.Changeset<action: :update,
# changes: %{title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!"},
# errors: [title: {"is too short", []}], data: #Post<>,
# valid?: false>, %{}}
PaperTrail.get_version(post)
# %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "update", id: 2, inserted_at: ~N[2016-09-15 22:00:59],
# item_changes: %{title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!"},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}}}
updated_post = Repo.get!(Post, 1)
PaperTrail.delete(updated_post)
# => on success:
# {:ok,
# %{model: %Post{__meta__: #Ecto.Schema.Metadata<:deleted, "posts">,
# title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!",
# id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 22:00:59]},
# version: %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "delete", id: 3, inserted_at: ~N[2016-09-15 22:22:12],
# item_changes: %{title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!",
# id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 22:00:59]},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}}}
Repo.aggregate(Post, :count, :id) # => 0
PaperTrail.Version.count() # => 3
# same as Repo.aggregate(PaperTrail.Version, :count, :id)
PaperTrail.Version.last() # returns the last version in the db by inserted_at
# %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "delete", id: 3, inserted_at: ~N[2016-09-15 22:22:12],
# item_changes: %{"title" => "Elixir matures fast", content: "Future is already here, Elixir is the next step!", "id" => 1,
# "inserted_at" => "2016-09-15T21:42:38",
# "updated_at" => "2016-09-15T22:00:59"},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}
PaperTrail is inspired by the ruby gem paper_trail
. However, unlike the paper_trail
gem this library actually results in less data duplication, faster and more explicit programming model to version your record changes.
The library source code is minimal and well tested. It is suggested to read the source code.
- Add paper_trail to your list of dependencies in
mix.exs
:
def deps do
[{:paper_trail, "~> 0.8.2"}]
end
- configure paper_trail to use your application repo in
config/config.exs
:
config :paper_trail, repo: YourApplicationName.Repo
# if you don't specify this PaperTrail will assume your repo name is Repo
- install and compile your dependency:
mix deps.get && mix compile
- run this command to generate the migration:
mix papertrail.install
You might want to edit the types for :item_id
or :originator_id
if you're
using UUID or other types for your primary keys before you execute
mix ecto.migrate
.
- run the migration:
mix ecto.migrate
Your application is now ready to collect some history!
YES! Make sure you do the steps above.
Column Name | Type | Description | Entry Method |
---|---|---|---|
event | String | either "insert", "update" or "delete" | Library generates |
item_type | String | model name of the reference record | Library generates |
item_id | configurable (Integer by default) | model id of the reference record | Library generates |
item_changes | Map | all the changes in this version as a map | Library generates |
originator_id | configurable (Integer by default) | foreign key reference to the creator/owner of this change | Optionally set |
origin | String | short reference to origin(eg. worker:activity-checker, migration, admin:33) | Optionally set |
meta | Map | any extra optional meta information about the version(eg. %{slug: "ausername", important: true}) | Optionally set |
inserted_at | Date | inserted_at timestamp | Ecto generates |
If you are using UUID or another type for your primary keys, you can configure the PaperTrail.Version schema to use it.
config :paper_trail, item_type: Ecto.UUID,
originator_type: Ecto.UUID
Remember to edit the types accordingly in the generated migration.
PaperTrail records have a string field called origin
. PaperTrail.insert/2
, PaperTrail.update/2
, PaperTrail.delete/2
functions accept a second argument to describe the origin of this version:
PaperTrail.update(changeset, origin: "migration")
# or:
PaperTrail.update(changeset, origin: "user:1234")
# or:
PaperTrail.delete(changeset, origin: "worker:delete_inactive_users")
# or:
PaperTrail.insert(new_user_changeset, origin: "password_registration")
# or:
PaperTrail.insert(new_user_changeset, origin: "facebook_registration")
You can specify setter/originator relationship to paper_trail versions with originator
assignment. This feature is only possible by specifying :originator
keyword list for your application configuration:
# in your config/config.exs
config :paper_trail, originator: [name: :user, model: YourApp.User]
# For most applications originator should be the user since models can be updated/created/deleted by several users.
Note: You will need to recompile your deps after you have added the config for originator.
Then originator name could be used for querying and preloading. Originator setting must be done via :originator
or originator name that is defined in the paper_trail configuration:
user = create_user()
# all these set originator_id's for the version records
PaperTrail.insert(changeset, originator: user)
{:ok, result} = PaperTrail.update(edit_changeset, originator: user)
# or you can use :user in the params instead of :originator if this is your config:
# config :paper_trail, originator: [name: :user, model: YourApplication.User]
{:ok, result} = PaperTrail.update(edit_changeset, user: user)
result[:version] |> Repo.preload(:user) |> Map.get(:user) # we can access the user who made the change from the version thanks to originator relationships!
PaperTrail.delete(edit_changeset, user: user)
Also make sure you have the foreign-key constraint in the database and in your version migration file.
You might want to add some meta data that doesn't belong to originator
and origin
fields. Such data could be stored in one object named meta
in paper_trail versions. Meta field could be passed as the second optional parameter to PaperTrail.insert/2, PaperTrail.update/2, PaperTrail.delete/2 functions:
company = Company.changeset(%Company{}, %{name: "Acme Inc."})
|> PaperTrail.insert(meta: %{slug: "acme-llc"})
# you can also combine this with an origin:
edited_company = Company.changeset(company, %{name: "Acme LLC"})
|> PaperTrail.update(origin: "documentation", meta: %{slug: "acme-llc"})
# or even with an originator:
user = create_user()
deleted_company = Company.changeset(edited_company, %{})
|> PaperTrail.delete(origin: "worker:github", originator: user, meta: %{slug: "acme-llc", important: true})
This is a feature more suitable for larger applications. Models can keep their version references via foreign key constraints. Therefore it would be impossible to delete the first and current version of a model if the model exists in the database, it also makes querying easier and the whole design more relational database/SQL friendly. In order to enable strict mode:
# in your config/config.exs
config :paper_trail, strict_mode: true
Strict mode expects tracked models to have foreign-key reference to their first_version and current_version. These columns must be named first_version_id
, and current_version_id
in their respective model tables. A tracked model example with a migration file:
# in the migration file: priv/repo/migrations/create_company.exs
defmodule Repo.Migrations.CreateCompany do
def change do
create table(:companies) do
add :name, :string, null: false
add :founded_in, :date
# null constraints are highly suggested:
add :first_version_id, references(:versions), null: false
add :current_version_id, references(:versions), null: false
timestamps()
end
create unique_index(:companies, [:first_version_id])
create unique_index(:companies, [:current_version_id])
end
end
# in the model definition:
defmodule Company do
use Ecto.Schema
import Ecto.Changeset
schema "companies" do
field :name, :string
field :founded_in, :date
belongs_to :first_version, PaperTrail.Version
belongs_to :current_version, PaperTrail.Version, on_replace: :update # on_replace: is important!
timestamps()
end
def changeset(struct, params \\ %{}) do
struct
|> cast(params, [:name, :founded_in])
end
end
When you run PaperTrail.insert/2 transaction, first_version_id
and current_version_id
automagically gets assigned for the model. Example:
company = Company.changeset(%Company{}, %{name: "Acme LLC"}) |> PaperTrail.insert
# {:ok,
# %{model: %Company{__meta__: #Ecto.Schema.Metadata<:loaded, "companies">,
# name: "Acme LLC", founded_in: nil, id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 21:42:38], first_version_id: 1, current_version_id: 1},
# version: %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "insert", id: 1, inserted_at: ~N[2016-09-15 22:22:12],
# item_changes: %{name: "Acme LLC", founded_in: nil, id: 1, inserted_at: ~N[2016-09-15 21:42:38]},
# originator_id: nil, origin: "unknown", meta: nil}}}
When you PaperTrail.update/2 a model, current_version_id
gets updated during the transaction:
edited_company = Company.changeset(company, %{name: "Acme Inc."}) |> PaperTrail.update(origin: "documentation")
# {:ok,
# %{model: %Company{__meta__: #Ecto.Schema.Metadata<:loaded, "companies">,
# name: "Acme Inc.", founded_in: nil, id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 23:22:12], first_version_id: 1, current_version_id: 2},
# version: %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "update", id: 2, inserted_at: ~N[2016-09-15 23:22:12],
# item_changes: %{name: "Acme Inc."}, originator_id: nil, origin: "documentation", meta: nil}}}
Additionally, you can put a null constraint on origin
column, you should always put an origin
reference to describe who makes the change. This is important for big applications because a model can change from many sources.
PaperTrail also supports PaperTrail.insert!
, PaperTrail.update!
, PaperTrail.delete!
. Naming of these functions intentionally match Repo.insert!
, Repo.update!
, Repo.delete!
functions. If PaperTrail is on strict_mode these bang functions will update the version references of the model just like the normal PaperTrail operations.
Bang functions assume the operation will always be successful, otherwise functions will raise Ecto.InvalidChangesetError
just like Repo.insert!
, Repo.update!
and Repo.delete!
:
changeset = Post.changeset(%Post{}, %{
title: "Word on the street is Elixir got its own database versioning library",
content: "You should try it now!"
})
inserted_post = PaperTrail.insert!(changeset)
# => on success:
# %Post{__meta__: #Ecto.Schema.Metadata<:loaded, "posts">,
# title: "Word on the street is Elixir got its own database versioning library",
# content: "You should try it now!", id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 21:42:38]
# }
#
# => on error raises: Ecto.InvalidChangesetError !!
inserted_post_version = PaperTrail.get_version(inserted_post)
# %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "insert", id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# item_changes: %{title: "Word on the street is Elixir got its own database versioning library",
# content: "You should try it now!", id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 21:42:38]},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}
edit_changeset = Post.changeset(inserted_post, %{
title: "Elixir matures fast",
content: "Future is already here, Elixir is the next step!"
})
updated_post = PaperTrail.update!(edit_changeset)
# => on success:
# %Post{__meta__: #Ecto.Schema.Metadata<:loaded, "posts">,
# title: "Elixir matures fast", content: "Future is already here, you deserve to be awesome!",
# id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 22:00:59]}
#
# => on error raises: Ecto.InvalidChangesetError !!
updated_post_version = PaperTrail.get_version(updated_post)
# %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "update", id: 2, inserted_at: ~N[2016-09-15 22:00:59],
# item_changes: %{title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!"},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil
# meta: nil}
PaperTrail.delete!(updated_post)
# => on success:
# %Post{__meta__: #Ecto.Schema.Metadata<:deleted, "posts">,
# title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!",
# id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 22:00:59]}
#
# => on error raises: Ecto.InvalidChangesetError !!
PaperTrail.get_version(updated_post)
# %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "delete", id: 3, inserted_at: ~N[2016-09-15 22:22:12],
# item_changes: %{title: "Elixir matures fast", content: "Future is already here, Elixir is the next step!",
# id: 1, inserted_at: ~N[2016-09-15 21:42:38],
# updated_at: ~N[2016-09-15 22:00:59]},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}
Repo.aggregate(Post, :count, :id) # => 0
PaperTrail.Version.count() # => 3
# same as Repo.aggregate(PaperTrail.Version, :count, :id)
PaperTrail.Version.last() # returns the last version in the db by inserted_at
# %PaperTrail.Version{__meta__: #Ecto.Schema.Metadata<:loaded, "versions">,
# event: "delete", id: 3, inserted_at: ~N[2016-09-15 22:22:12],
# item_changes: %{"title" => "Elixir matures fast", content: "Future is already here, Elixir is the next step!", "id" => 1,
# "inserted_at" => "2016-09-15T21:42:38",
# "updated_at" => "2016-09-15T22:00:59"},
# item_id: 1, item_type: "Post", originator_id: nil, originator: nil, meta: nil}
Sometimes you have to deal with applications where you need multi tenancy capabilities, and you want to keep tracking of the versions of your data on different schemas (PostgreSQL) or databases (MySQL).
You can use the Ecto.Query prefix in order to switch between different schemas/databases for your own data, so you can specify in your changeset where to store your record. Example:
tenant = "tenant_id"
changeset = User.changeset(%User{}, %{first_name: "Izel", last_name: "Nakri"})
changeset
|> Ecto.Queryable.to_query()
|> Map.put(:prefix, tenant)
|> Repo.insert()
PaperTrail also allows you to store the Version
entries generated by your activity in
different schemas/databases by using the value of the element :prefix
on the options
of the functions. Example:
tenant = "tenant_id"
changeset =
User.changeset(%User{}, %{first_name: "Izel", last_name: "Nakri"})
|> Ecto.Queryable.to_query()
|> Map.put(:prefix, tenant)
PaperTrail.insert(changeset, [prefix: tenant])
By doing this, you're storing the new User
entry into the schema/database
specified by the :prefix
value (tenant_id
).
Note that the User
's changeset it's sent with the :prefix
, so PaperTrail will take care of the
storage of the generated Version
entry in the desired schema/database. Make sure
to add this prefix to your changeset before the execution of the PaperTrail function if you want to do versioning on a seperate schema.
PaperTrail can also get versions of records or models from different schemas/databases as well
by using the :prefix
option. Example:
tenant = "tenant_id"
id = 1
PaperTrail.get_versions(User, id, [prefix: tenant])
- PaperTrail.Version(s) order matter,
- don't delete your paper_trail versions, instead you can merge them
- If you have a question or a problem, do not hesitate to create an issue or submit a pull request
Many thanks to:
- Jose Pablo Castro - Built the repo configuration for paper_trail
- Florian Gerhardt - Fixed rare compile errors for PaperTrail repos
- Alex Antonov - Original inventor of the originator feature
- Moritz Schmale - UUID primary keys feature
- Jason Draper - UUID primary keys feature
- Josh Taylor - Maintenance and new feature suggestions
- Mitchell Henke - Fixed weird elixir compiler warnings
- Iván González - Multi tenancy feature and some minor refactors
- Teo Choong Ping - Fixed paper_trail references for newer Elixir versions
- devvit - Added non-regular primary key tracking support
- rustamtolipov - Added support for Ecto v3
- gabrielpra1 - Added enhanced support for Ecto.Changeset
- Izel Nakri - The Originator of this library. See what I did there ;)
Additional thanks to:
- Ruby paper_trail gem - Initial inspiration of this project.
- Ecto - For the great API.