support ForwardRef in Python 3.6 #706

koxudaxi · 2019-08-02T04:30:32Z

Change Summary

Support ForwardRef in Python 3.6.
The Feature is talked in the issue. #463
The PR supports features on this list in Python 3.6

_ForwardRef
resolve string annotations (eg. List['User'])
update_forward_refs

Related issue number

#463

Checklist

Unit tests for the changes exist
Tests pass on CI and coverage remains at 100%
Documentation reflects the changes where applicable
HISTORY.rst has been updated
- if this is the first change since a release, please add a new section
- include the issue number or this pull request number #<number>
- include your github username @<whomever>

codecov · 2019-08-02T06:20:33Z

Codecov Report

Merging #706 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #706   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines        2721   2725    +4     
  Branches      539    539           
=====================================
+ Hits         2721   2725    +4

samuelcolvin

otherwise looks good to me.

samuelcolvin · 2019-08-02T10:09:51Z

tests/test_py36.py

@@ -0,0 +1,300 @@
+"""


looks like much of this might be duplicates of the python 3.7 tests? couldn't we just remove the "skip" and run the same test for both? (At least in some cases).

Python 3.6 and pyhton3.7 are a little different (eg. _ForwardRef and ForwardRef).
I have to change exists test code.
I try to do it.

great, I think better to have one set of tests than two, even if it means a bit of repeated try:...except: or if sys.version...else.

I have changed test_py37.py to test_forward_ref.py and deleted test_py36.py

StephenBrown2 · 2019-08-02T20:00:56Z

Does this mean, to support Python 3.6 in my code, I will need to add

try:
    from typing import ForwardRef
except ImportError:
    from typing import _ForwardRef as ForwardRef

anywhere I have need of a forward ref? Or will self-referencing strings still work fine? This makes me think it will, so I'm hoping so.

e.g.

this currently works for me in Python 3.7:

from typing import List

from pydantic import BaseModel

class CalendarRule(BaseModel):
    id: int
    calendar: int
    children: List["CalendarRule"]
    ordering: int
    rule_attribute: str
    rule_value: str


CalendarRule.update_forward_refs()

but I will not be able to reference it by string value, and instead will need to do:

from typing import List

from pydantic import BaseModel

try:
    from typing import ForwardRef
except ImportError:
    from typing import _ForwardRef as ForwardRef

CalendarRule = ForwardRef("CalendarRule")

class CalendarRule(BaseModel):
    id: int
    calendar: int
    children: List[CalendarRule]
    ordering: int
    rule_attribute: str
    rule_value: str


CalendarRule.update_forward_refs()

koxudaxi · 2019-08-03T05:33:37Z

@StephenBrown2

Does this mean, to support Python 3.6 in my code, I will need to add

Yes, If you need ForwardRef in Python3.6 and python3.7

anywhere I have need of a forward ref? Or will self-referencing strings still work fine? This makes me think it will, so I'm hoping so.

No, you don't need forward ref. you can use self-referencing string in python3.6 and python3.7.

Also, you can install the PR version in your local machine to try it.
$ pip install git+https://github.com/koxudaxi/pydantic.git@support_forwardred_in_python36

samuelcolvin · 2019-08-05T09:46:15Z

tests/test_forward_ref.py

 def test_forward_ref_dataclass(create_module):
    module = create_module(
        """
-from __future__ import annotations


I think we still need a 3.7 only test with from __future__ import annotations to check that this works with future annotations.

I have added unittest for python3.7

samuelcolvin · 2019-08-05T09:47:04Z

tests/test_forward_ref.py

 from typing import List
 from pydantic import BaseModel, Schema

 class Account(BaseModel):
  name: str
-  subaccounts: List[Account] = []
+  subaccounts: List['Account'] = []


again I'm afraid I think we need both this test and the 3.7 only test with from __future__ import annotations

I add unittest for python3.7

samuelcolvin · 2019-08-05T09:47:18Z

tests/test_forward_ref.py

 def test_circular_reference_json_schema(create_module):
    module = create_module(
        """
-from __future__ import annotations


and I add unittest for python3.7.

samuelcolvin · 2019-08-05T09:47:32Z

tests/test_forward_ref.py

 def test_self_forward_ref_collection(create_module):
    module = create_module(
        """
-from typing import ForwardRef, List, Dict
+from typing import List, Dict
+try:


might be good to add this to pydantic.utils.

Then you can do from pydantic.utils import ForwardRef in tests but also people can use that in their own code if they want to work with 3.6 and 3.7?

OK, I add pydantic.utils.
They can use from pydantic.utils import ForwardRef with 3.6 and 3.7.

…d_in_python36

koxudaxi · 2019-08-05T12:10:09Z

I have merged history :)

samuelcolvin · 2019-08-05T12:27:33Z

great, thank you very much.

StephenBrown2 · 2019-08-06T14:34:05Z

Woohoo! Looking forward to v0.32 now! Thanks very much for this.

koxudaxi added 2 commits August 2, 2019 13:22

support ForwardRef in Python 3.6

a4292aa

add evaluate_forwardref()

a1f4f2a

koxudaxi added 3 commits August 2, 2019 15:45

update README and History

45b4223

remove unnecessary a assignment

572239b

fix skip_not_36 condition

84d7c4a

samuelcolvin reviewed Aug 2, 2019

View reviewed changes

change test_py37.py to test_forward_ref.py

8e0455c

delete @skip_not_37 on forward_ref tests

879a24e

samuelcolvin reviewed Aug 5, 2019

View reviewed changes

koxudaxi added 3 commits August 5, 2019 20:46

add unittest for python3.7

cffcb39

Merge remote-tracking branch 'upstream/master' into support_forwardre…

b5d5e59

…d_in_python36

merge HISTORY

75afb3f

samuelcolvin merged commit 6be7c21 into pydantic:master Aug 5, 2019

koxudaxi mentioned this pull request Aug 5, 2019

Add jsonschemaobject koxudaxi/datamodel-code-generator#36

Merged

alexdrydew pushed a commit to alexdrydew/pydantic that referenced this pull request Dec 23, 2023

Allow proper subclasses of strings (pydantic#706)

424a2f8

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support ForwardRef in Python 3.6 #706

support ForwardRef in Python 3.6 #706

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koxudaxi commented Aug 5, 2019

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samuelcolvin commented Aug 5, 2019

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StephenBrown2 commented Aug 6, 2019

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koxudaxi commented Aug 2, 2019 •

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