Pydantic Literal enum bug in 1.8+

bug.py

from typing import Literal
from enum import Enum
import logging

from pydantic import BaseModel, ValidationError
from pydantic.utils import version_info


print("=== PYDANTIC INFO ===")
print(version_info())


class MyEnum(str, Enum):
    FOO = "foo"
    BAR = "bar"



print("\n\n=== ModelWithLiteralEnumMember ===")

class ModelWithLiteralEnumMember(BaseModel):
    kind: Literal[MyEnum.FOO]

print("\n---- Parse model ----")
print(ModelWithLiteralEnumMember(kind="foo"))
try:
    print(ModelWithLiteralEnumMember(kind="bar"))
except ValidationError:
    print("OK - Can validate the enum")

print("\n---- Get JSON schema ----")
try:
    print(ModelWithLiteralEnumMember.schema_json())  # This works until 1.7.3 but crashes on 1.8+
except KeyError:
    logging.exception("Cannot get JSON schema for ModelWithLiteralEnumMember")



print("\n\n=== ModelWithLiteralEnumMemberAndForwardRef ===")

class ModelWithLiteralEnumMemberAndForwardRef(BaseModel):
    kind: Literal[MyEnum.FOO]

ModelWithLiteralEnumMemberAndForwardRef.update_forward_refs()

print("\n---- Parse model ----")
print(ModelWithLiteralEnumMemberAndForwardRef(kind="foo"))
try:
    print(ModelWithLiteralEnumMemberAndForwardRef(kind="bar"))
except ValidationError:
    print("OK - Can validate the enum")

print("\n---- Get JSON schema ----")
try:
    print(ModelWithLiteralEnumMemberAndForwardRef.schema_json())  # Still doesn't work...
except KeyError:
    logging.exception("Cannot get JSON schema for ModelWithLiteralEnumMemberAndForwardRef")



print("\n\n=== ModelWithLiteralEnumMemberAndFullEnum ===")

class ModelWithLiteralEnumMemberAndFullEnum(BaseModel):
    kind: Literal[MyEnum.FOO]
    possible_kinds: MyEnum

print("\n---- Get JSON schema ----")
print(ModelWithLiteralEnumMemberAndFullEnum.schema_json())  # ... but now with the new property it does work



print("\n\n=== ModelWithLiteralEnumValue ===")

class ModelWithLiteralEnumValue(BaseModel):
    kind: Literal[MyEnum.FOO.value]

print("\n---- Parse model ----")
print(ModelWithLiteralEnumValue(kind="foo"))
try:
    print(ModelWithLiteralEnumValue(kind="bar"))
except ValidationError:
    print("OK - Can validate the enum")

print("\n---- Get JSON schema ----")
print(ModelWithLiteralEnumValue.schema_json())



print("\n\n=== ModelWithLiteralEnumValue ===")

class ModelWithLiteralStr(BaseModel):
    kind: Literal["foo"]

print("\n---- Parse model ----")
print(ModelWithLiteralStr(kind="foo"))
try:
    print(ModelWithLiteralStr(kind="bar"))
except ValidationError:
    print("OK - Can validate the enum")

print("\n---- Get JSON schema ----")
print(ModelWithLiteralStr.schema_json())

result-1.7.3.txt

=== PYDANTIC INFO ===
             pydantic version: 1.7.3
            pydantic compiled: True
                 install path: /tmp/tmp.iid8D0iv22/.venv/lib/python3.9/site-packages/pydantic
               python version: 3.9.2 (default, Feb 20 2021, 18:40:11)  [GCC 10.2.0]
                     platform: Linux-5.11.6-arch1-1-x86_64-with-glibc2.33
     optional deps. installed: []


=== ModelWithLiteralEnumMember ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumMember", "type": "object", "properties": {"kind": {"title": "Kind", "$ref": "#/definitions/MyEnum"}}, "required": ["kind"], "definitions": {"MyEnum": {"title": "MyEnum", "description": "An enumeration.", "enum": ["foo", "bar"], "type": "string"}}}


=== ModelWithLiteralEnumMemberAndForwardRef ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumMemberAndForwardRef", "type": "object", "properties": {"kind": {"title": "Kind", "$ref": "#/definitions/MyEnum"}}, "required": ["kind"], "definitions": {"MyEnum": {"title": "MyEnum", "description": "An enumeration.", "enum": ["foo", "bar"], "type": "string"}}}


=== ModelWithLiteralEnumMemberAndFullEnum ===

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumMemberAndFullEnum", "type": "object", "properties": {"kind": {"title": "Kind", "$ref": "#/definitions/MyEnum"}, "possible_kinds": {"$ref": "#/definitions/MyEnum"}}, "required": ["kind", "possible_kinds"], "definitions": {"MyEnum": {"title": "MyEnum", "description": "An enumeration.", "enum": ["foo", "bar"], "type": "string"}}}


=== ModelWithLiteralEnumValue ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumValue", "type": "object", "properties": {"kind": {"title": "Kind", "const": "foo", "type": "string"}}, "required": ["kind"]}


=== ModelWithLiteralEnumValue ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralStr", "type": "object", "properties": {"kind": {"title": "Kind", "const": "foo", "type": "string"}}, "required": ["kind"]}

result-1.8.0.txt

=== PYDANTIC INFO ===
             pydantic version: 1.8
            pydantic compiled: True
                 install path: /tmp/tmp.iid8D0iv22/.venv/lib/python3.9/site-packages/pydantic
               python version: 3.9.2 (default, Feb 20 2021, 18:40:11)  [GCC 10.2.0]
                     platform: Linux-5.11.6-arch1-1-x86_64-with-glibc2.33
     optional deps. installed: ['typing-extensions']


=== ModelWithLiteralEnumMember ===

---- Parse model ----
kind=<MyEnum.FOO: 'foo'>
OK - Can validate the enum

---- Get JSON schema ----
ERROR:root:Cannot get JSON schema for ModelWithLiteralEnumMember
Traceback (most recent call last):
  File "/tmp/tmp.iid8D0iv22/main.py", line 33, in <module>
    print(ModelWithLiteralEnumMember.schema_json())  # This works until 1.7.3 but crashes on 1.8+
  File "pydantic/main.py", line 706, in pydantic.main.BaseModel.schema_json
  File "pydantic/main.py", line 695, in pydantic.main.BaseModel.schema
  File "pydantic/schema.py", line 167, in pydantic.schema.model_schema
  File "pydantic/schema.py", line 548, in pydantic.schema.model_process_schema
  File "pydantic/schema.py", line 589, in pydantic.schema.model_type_schema
  File "pydantic/schema.py", line 241, in pydantic.schema.field_schema
  File "pydantic/schema.py", line 495, in pydantic.schema.field_type_schema
  File "pydantic/schema.py", line 810, in pydantic.schema.field_singleton_schema
KeyError: <enum 'MyEnum'>


=== ModelWithLiteralEnumMemberAndForwardRef ===

---- Parse model ----
kind=<MyEnum.FOO: 'foo'>
OK - Can validate the enum

---- Get JSON schema ----
ERROR:root:Cannot get JSON schema for ModelWithLiteralEnumMemberAndForwardRef
Traceback (most recent call last):
  File "/tmp/tmp.iid8D0iv22/main.py", line 55, in <module>
    print(ModelWithLiteralEnumMemberAndForwardRef.schema_json())  # Still doesn't work...
  File "pydantic/main.py", line 706, in pydantic.main.BaseModel.schema_json
  File "pydantic/main.py", line 695, in pydantic.main.BaseModel.schema
  File "pydantic/schema.py", line 167, in pydantic.schema.model_schema
  File "pydantic/schema.py", line 548, in pydantic.schema.model_process_schema
  File "pydantic/schema.py", line 589, in pydantic.schema.model_type_schema
  File "pydantic/schema.py", line 241, in pydantic.schema.field_schema
  File "pydantic/schema.py", line 495, in pydantic.schema.field_type_schema
  File "pydantic/schema.py", line 810, in pydantic.schema.field_singleton_schema
KeyError: <enum 'MyEnum'>


=== ModelWithLiteralEnumMemberAndFullEnum ===

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumMemberAndFullEnum", "type": "object", "properties": {"kind": {"title": "Kind", "$ref": "#/definitions/MyEnum"}, "possible_kinds": {"$ref": "#/definitions/MyEnum"}}, "required": ["kind", "possible_kinds"], "definitions": {"MyEnum": {"title": "MyEnum", "description": "An enumeration.", "enum": ["foo", "bar"], "type": "string"}}}


=== ModelWithLiteralEnumValue ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumValue", "type": "object", "properties": {"kind": {"title": "Kind", "enum": ["foo"], "type": "string"}}, "required": ["kind"]}


=== ModelWithLiteralEnumValue ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralStr", "type": "object", "properties": {"kind": {"title": "Kind", "enum": ["foo"], "type": "string"}}, "required": ["kind"]}

result-1.8.1.txt

=== PYDANTIC INFO ===
             pydantic version: 1.8.1
            pydantic compiled: True
                 install path: /tmp/tmp.iid8D0iv22/.venv/lib/python3.9/site-packages/pydantic
               python version: 3.9.2 (default, Feb 20 2021, 18:40:11)  [GCC 10.2.0]
                     platform: Linux-5.11.6-arch1-1-x86_64-with-glibc2.33
     optional deps. installed: ['typing-extensions']


=== ModelWithLiteralEnumMember ===

---- Parse model ----
kind=<MyEnum.FOO: 'foo'>
OK - Can validate the enum

---- Get JSON schema ----
ERROR:root:Cannot get JSON schema for ModelWithLiteralEnumMember
Traceback (most recent call last):
  File "/tmp/tmp.iid8D0iv22/main.py", line 33, in <module>
    print(ModelWithLiteralEnumMember.schema_json())  # This works until 1.7.3 but crashes on 1.8+
  File "pydantic/main.py", line 715, in pydantic.main.BaseModel.schema_json
  File "pydantic/main.py", line 704, in pydantic.main.BaseModel.schema
  File "pydantic/schema.py", line 167, in pydantic.schema.model_schema
  File "pydantic/schema.py", line 548, in pydantic.schema.model_process_schema
  File "pydantic/schema.py", line 589, in pydantic.schema.model_type_schema
  File "pydantic/schema.py", line 241, in pydantic.schema.field_schema
  File "pydantic/schema.py", line 495, in pydantic.schema.field_type_schema
  File "pydantic/schema.py", line 810, in pydantic.schema.field_singleton_schema
KeyError: <enum 'MyEnum'>


=== ModelWithLiteralEnumMemberAndForwardRef ===

---- Parse model ----
kind=<MyEnum.FOO: 'foo'>
OK - Can validate the enum

---- Get JSON schema ----
ERROR:root:Cannot get JSON schema for ModelWithLiteralEnumMemberAndForwardRef
Traceback (most recent call last):
  File "/tmp/tmp.iid8D0iv22/main.py", line 55, in <module>
    print(ModelWithLiteralEnumMemberAndForwardRef.schema_json())  # Still doesn't work...
  File "pydantic/main.py", line 715, in pydantic.main.BaseModel.schema_json
  File "pydantic/main.py", line 704, in pydantic.main.BaseModel.schema
  File "pydantic/schema.py", line 167, in pydantic.schema.model_schema
  File "pydantic/schema.py", line 548, in pydantic.schema.model_process_schema
  File "pydantic/schema.py", line 589, in pydantic.schema.model_type_schema
  File "pydantic/schema.py", line 241, in pydantic.schema.field_schema
  File "pydantic/schema.py", line 495, in pydantic.schema.field_type_schema
  File "pydantic/schema.py", line 810, in pydantic.schema.field_singleton_schema
KeyError: <enum 'MyEnum'>


=== ModelWithLiteralEnumMemberAndFullEnum ===

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumMemberAndFullEnum", "type": "object", "properties": {"kind": {"title": "Kind", "$ref": "#/definitions/MyEnum"}, "possible_kinds": {"$ref": "#/definitions/MyEnum"}}, "required": ["kind", "possible_kinds"], "definitions": {"MyEnum": {"title": "MyEnum", "description": "An enumeration.", "enum": ["foo", "bar"], "type": "string"}}}


=== ModelWithLiteralEnumValue ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralEnumValue", "type": "object", "properties": {"kind": {"title": "Kind", "enum": ["foo"], "type": "string"}}, "required": ["kind"]}


=== ModelWithLiteralEnumValue ===

---- Parse model ----
kind='foo'
OK - Can validate the enum

---- Get JSON schema ----
{"title": "ModelWithLiteralStr", "type": "object", "properties": {"kind": {"title": "Kind", "enum": ["foo"], "type": "string"}}, "required": ["kind"]}