A mix task for generating an ERD (Entity-Relationship Diagram) in various formats for all Ecto schemas in your project.

Supported formats:

• DOT (default)
• PlantUML
• DBML
• QuickDBD
• Mermaid

defmodule Blog.Post do use Ecto.Schema schema "posts" do field(:title, :string) field(:text, :string) timestamps() belongs_to(:user, Blog.User) has_many(:comments, Blog.Comment) end end defmodule Blog.Comment do use Ecto.Schema schema "comments" do field(:text, :string) timestamps() belongs_to(:post, Blog.Post) belongs_to(:user, Blog.User) end end defmodule Blog.User do use Ecto.Schema schema "users" do field(:email, :string) has_many(:posts, Blog.Post) has_many(:comments, Blog.Comment) end end

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

def deps do [ {:ecto_erd, "~> 0.6", only: :dev} ] end

Just run:

mix ecto.gen.erd

The command above produces a DOT file, which you can convert to an image using the Graphviz utility:

dot -Tpng ecto_erd.dot -o erd.png

Configuration is possible via the .ecto_erd.exs file. The docs can be found at https://hexdocs.pm/ecto_erd. Configuration examples and output for a few open-source projects can be found in the PAGES section under EXAMPLES.

Trying to run ecto_erd in an umbrella project? You might see this error:

$ mix ecto.gen.erd ** (RuntimeError) Unable to detect `:otp_app`, please specify it explicitly 

The easiest solution is to run the command on one of the apps in the apps/ directory. Another option is to create a configuration file and specify the :otp_app. See the docs for details.