Examples

The examples below use the same small sample application to demonstrate different output formats and configuration options.

Configuration	Format	Source	Rendered
Default	DBML	Document	—
Default	DOT	Document	SVG
Default	QuickDBD	Document	—
Default	PlantUML	Document	SVG
Default	Mermaid	Document	—
Default	D2	Document	SVG
Field comments	Mermaid	Document	—
No fields	DOT	Document	—
No fields	Mermaid	Document	—
No fields	D2	Document	—
Contexts as clusters	DBML	Document	—
Contexts as clusters	DOT	Document	—
Contexts as clusters	PlantUML	Document	—
Contexts as clusters	D2	Document	—

Rendered demos

DOT

Default DOT entity-relationship diagram

D2

Default D2 entity-relationship diagram

PlantUML

Default PlantUML entity-relationship diagram

Configuration files

Default

No configuration file is needed.

Field comments

# .ecto_erd.exs
alias Ecto.ERD.{Field, Node}
alias Ecto.ERD.Example.Accounts.User

[
  map_node: fn
    %Node{schema_module: User} = node ->
      update_in(node.fields, fn fields ->
        Enum.map(fields, fn
          %Field{name: :email} = field -> %{field | comment: "Unique sign-in address"}
          field -> field
        end)
      end)

    node ->
      node
  end
]

No fields

# .ecto_erd.exs
[
  columns: []
]

Contexts as clusters

# .ecto_erd.exs
alias Ecto.ERD.Node

[
  map_node: fn
    %Node{schema_module: schema_module} = node when not is_nil(schema_module) ->
      case Module.split(schema_module) do
        ["Ecto", "ERD", "Example", context | _] -> Node.set_cluster(node, context)
        _ -> node
      end

    node ->
      node
  end
]