How to define an Enum Input in mutation?

In models.py, I defined a python Enum class:

class EmployeeKind(PyEnum):
    contractor = 1
    fulltime = 2
    parttime = 3

and in schema.py, I defined a mutation class:

class UpdateEmployee(graphene.Mutation):
    class Arguments:
        id = graphene.ID(required=True)
        name = graphene.String()
        department_id = graphene.ID()
        role_id = graphene.ID()
        kind = graphene.Enum.from_enum(EmployeeKind)
...

But when running the script, it shows an error:

Traceback (most recent call last):
  File "....../gqlsql/./app.py", line 5, in <module>
    from schema import schema
  File "....../gqlsql/schema.py", line 181, in <module>
    class Mutation(graphene.ObjectType):
  File "....../gqlsql/schema.py", line 183, in Mutation
    update_employee = UpdateEmployee.Field()
  File "....../gqlsql/.venv/lib/python3.9/site-packages/graphene/types/mutation.py", line 139, in Field
    return Field(
  File "....../gqlsql/.venv/lib/python3.9/site-packages/graphene/types/field.py", line 103, in __init__
    self.args = to_arguments(args or OrderedDict(), extra_args)
  File "....../gqlsql/.venv/lib/python3.9/site-packages/graphene/types/argument.py", line 104, in to_arguments
    raise ValueError('Unknown argument "{}".'.format(default_name))
ValueError: Unknown argument "kind".

What does this error mean? Why?

[chrisberks]

graphene.Enum.from_enum(EmployeeKind) returns a type object which you then need to call.

This:

class EmployeeKindEnum(PyEnum):
    contractor = 1
    fulltime = 2
    parttime = 3

EmployeeKind = graphene.Enum.from_enum(EmployeeKindEnum)

is essentially a dynamic form of:

class EmployeeKind(graphene.Enum):
    contractor = 1
    fulltime = 2
    parttime = 3

except the first is based on an existing Python Enum.

Example:

# models.py
import enum

class EmployeeKind(enum.Enum):
    contractor = 1
    fulltime = 2
    parttime = 3

# schema.py
import graphene

from models import EmployeeKind as EmployeeKindEnum

EmployeeKind = graphene.Enum.from_enum(EmployeeKindEnum)

class UpdateEmployee(graphene.Mutation):
    class Arguments:
        id = graphene.ID(required=True)
        name = graphene.String()
        department_id = graphene.ID()
        role_id = graphene.ID()
        kind = EmployeeKind(required=True)

[chrisberks]

Thanks @shaozi!

You’re right about the Enums. Graphene v3 has better Enum support, resolvers will receive the Enum member directly rather than the value—as you suggest.

Graphene v3 is still in beta though, Graphene-SQLAlchemy is using v2.