Defining Enums

Exograph supports enums, which are a way to define a set of allowed values for a field. Enums are defined using the enum keyword.

@postgres
module TaskDatabase {
  enum Priority {
    LOW
    MEDIUM
    HIGH
  }
}

Exograph will map the Priority enum to the priority enumerated type in the database. For naming, Exograph uses the same convention as for types: it converts the enum name to a "snake_case" name.

Once defined, enums can be used in type definitions as if they were scalars.

type Todo {
  @pk id: Int = autoIncrement()
  title: String
  priority: Priority = MEDIUM
}

The priority field is now restricted to the values LOW, MEDIUM, and HIGH. If you try to set it to any other value, Exograph will return an error.

You use fields of enum type in queries and mutations just like any other scalar type. For example, the following mutation creates a new todo with a low priority.

mutation {
  createTodo(title: "Buy groceries", priority: LOW) {
    id
  }
}

Whereas the following query will return all todos with a medium priority.

query {
  todos(where: { priority: { eq: MEDIUM } }) { 
    id
    title
    priority
  }
}