upgrade-marshmallow

Upgrade marshmallow is a tool to batch modify call expression with marshmallow.fields.Field.

• Free software: MIT license
• Documentation: https://upgrade-marshmallow.readthedocs.io.

Problem

After upgrade marshmallow>=3.10.0, the non-reserved arguments(e.g. title, description) should passing in by metadata argument.

Otherwise, it will pop RemovedInMarshmallow4Warning(when running pytest).

Duplicate

code structure:

$ tree .
.
├── requirements.txt  # marshmallow==3.3.0
├── schemas.py
└── test_warning.py

example code(schemas.py):

from marshmallow import Schema
from marshmallow import fields


class FooSchema(Schema):
    name = fields.String(
        required=True,
        title='foo',
        description='foo name')
    relationship = fields.String(
        title='bar', description='foobar')

test code(test_warning.py):

from schemas import FooSchema


def test_warn():
    INPUT = {
        'name': 'something',
        'relationship': 'others'
    }
    schema = FooSchema()
    data = schema.load(INPUT)
    assert data == INPUT

upgrade marshmallow and duplicate this problem:

$ pip install -U marshmallow
...
Successfully installed marshmallow-3.14.1

$ pytest test_warning.py
================== test session starts ================================
platform darwin -- Python 3.8.3, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: /private/tmp/_
collected 1 item

test_warning.py .                                                                                                                              [100%]

================== warnings summary =================================
.venv/lib/python3.8/site-packages/marshmallow/fields.py:218
/private/tmp/_/.venv/lib/python3.8/site-packages/marshmallow/fields.py:218: RemovedInMarshmallow4Warning: Passing field metadata as keyword arguments is deprecated. Use the explicit `metadata=...` argument instead. Additional metadata: {'title': 'foo', 'description': 'foo name'}
warnings.warn(

.venv/lib/python3.8/site-packages/marshmallow/fields.py:218
/private/tmp/_/.venv/lib/python3.8/site-packages/marshmallow/fields.py:218: RemovedInMarshmallow4Warning: Passing field metadata as keyword arguments is deprecated. Use the explicit `metadata=...` argument instead. Additional metadata: {'title': 'bar', 'description': 'foobar'}
warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/warnings.html
================== 1 passed, 2 warnings in 0.03s ===================

Issue

In some projects, we may use a lot of Field with "title", "description" etc. arguments.

It will take lots of effort to change each one by one manually, and it's not easy to "replace" by editor tools or use awk/sed.

Solution

upgrade-marshmallow use AST to parsing source code, then replacing arguments with expected code.

Features

upgrade-marshmallow tool could handler many cases.

1. the most common(simple) way to use marshmallow.fields.Field:

.. literalinclude:: ../tests/samples/most_common/schemas.py
   :language: python

2. alias fields:

.. literalinclude:: ../tests/samples/alias_fields/schemas.py
   :language: python

3. import marshmallow, using Field with absolute path:

.. literalinclude:: ../tests/samples/absolute/schemas.py
   :language: python

4. alias marshmallow:

.. literalinclude:: ../tests/samples/alias_absolute/schemas.py
   :language: python

5. directly import to Field

.. literalinclude:: ../tests/samples/field_func/schemas.py
   :language: python

6. rename default to dump_default, missing to load_default

.. literalinclude:: ../tests/samples/default_missing/schemas.py
   :language: python