D2 Output¶

We support the D2 diagramming language as an output format.

CLI¶

To generate D2 language output, use the --d2 flag.

In [1]:

!erdantic erdantic.examples.pydantic.Party --d2

!erdantic erdantic.examples.pydantic.Party --d2

2025-10-08 22:10:25,039 | erdantic.core | INFO | Adding model 'erdantic.examples.pydantic.Party' to diagram...
"Adventurer": {
  shape: class
  +name: str
  +profession: str
  +alignment: Alignment
  +level: int
}

"Party": {
  shape: class
  +name: str
  +formed_datetime: datetime
  +members: "list[Adventurer]"
  +active_quest: "Optional[Quest]"
}

"Quest": {
  shape: class
  +name: str
  +giver: QuestGiver
  +reward_gold: int
}

"QuestGiver": {
  shape: class
  +name: str
  +faction: "Optional[str]"
  +location: str
}

"Party" -> "Quest": "active_quest" {
  target-arrowhead.shape: cf-one
}

"Party" -> "Adventurer": "members" {
  target-arrowhead.shape: cf-many
}

"Quest" -> "QuestGiver": "giver" {
  target-arrowhead.shape: cf-one-required
}

Python library¶

To generate D2 output using the Python library, use the to_d2 method on EntityRelationshipDiagram.

In [2]:

import erdantic as erd
from erdantic.examples.pydantic import Party

diagram = erd.create(Party)

print(diagram.to_d2())

import erdantic as erd from erdantic.examples.pydantic import Party diagram = erd.create(Party) print(diagram.to_d2())

"Adventurer": {
  shape: class
  +name: str
  +profession: str
  +alignment: Alignment
  +level: int
}

"Party": {
  shape: class
  +name: str
  +formed_datetime: datetime
  +members: "list[Adventurer]"
  +active_quest: "Optional[Quest]"
}

"Quest": {
  shape: class
  +name: str
  +giver: QuestGiver
  +reward_gold: int
}

"QuestGiver": {
  shape: class
  +name: str
  +faction: "Optional[str]"
  +location: str
}

"Party" -> "Quest": "active_quest" {
  target-arrowhead.shape: cf-one
}

"Party" -> "Adventurer": "members" {
  target-arrowhead.shape: cf-many
}

"Quest" -> "QuestGiver": "giver" {
  target-arrowhead.shape: cf-one-required
}