Instance of 'Field' has no 'append' member

[yellowhat]

Bug description

Hi,
I have the following code:

from dataclasses import field
from typing import List
from pydantic.dataclasses import dataclass

@dataclass
class Case:
    """Case class (group Item)"""

    name: str
    irr: float = 0
    items: List[Item] = field(default_factory=lambda: [])

    def add_item(self, item: Item) -> None:
        """Add an item to the item list."""

        self.items.append(item)

    def find_item(self, description: str) -> Item:
        """Find an item by description"""

        return next((item for item in self.items if item.description == description), None)

With version 2.10.2, pylint returns:

E1101: Instance of 'Field' has no 'append' member (no-member)

Is this related to pylint-dev/astroid#1126?

Thanks

Configuration

No response

Command used

pylint --verbose --disable=W0123 --max-locals=20 --extension-pkg-whitelist="pydantic" --max-line-length=480 **/*.py

Pylint output

************* Module tco.classes
tco/classes.py:240:8: E1101: Instance of 'Field' has no 'append' member (no-member)
tco/classes.py:245:38: E1133: Non-iterable value self.items is used in an iterating context (not-an-iterable)

Expected behavior

No errors

Pylint version

astroid-2.7.2 iniconfig-1.1.1 isort-5.9.3 lazy-object-proxy-1.6.0 platformdirs-2.2.0 pluggy-0.13.1 py-1.10.0 pylint-2.10.2 pytest-6.2.4 toml-0.10.2 wrapt-1.12.1

OS / Environment

No response

Additional dependencies

No response

[david-yz-liu]

Yup, I can reproduce this! I can work on this one.

[yellowhat]

Hi,
I can see the same error with astroid-2.7.3:

Successfully installed astroid-2.7.3 iniconfig-1.1.1 isort-5.9.3 lazy-object-proxy-1.6.0 pluggy-1.0.0 py-1.10.0 pylint-2.10.2 pytest-6.2.5 toml-0.10.2 wrapt-1.12.1

E1101: Instance of 'Field' has no 'append' member (no-member)
E1133: Non-iterable value self.items is used in an iterating context (not-an-iterable)

Should I wait for pylint 2.11.0?

Thanks

[Pierre-Sassoulas]

There was no changes in pylint so using astroid to 2.7.3 is supposed to work imo. What do you think @david-yz-liu ?

[david-yz-liu]

Hmmm, yes it should be working. I can't reproduce this locally (Windows):

$ pylint --version
pylint 2.10.2
astroid 2.7.3
Python 3.9.1 (tags/v3.9.1:1e5d33e, Dec  7 2020, 17:08:21) [MSC v.1927 64 bit (AMD64)]

$ cat issue1158.py
from dataclasses import field
from typing import List
from pydantic.dataclasses import dataclass


@dataclass
class Item:
    description: str


@dataclass
class Case:
    """Case class (group Item)"""

    name: str
    irr: float = 0
    items: List[Item] = field(default_factory=lambda: [])

    def add_item(self, item: Item) -> None:
        """Add an item to the item list."""

        self.items.append(item)

    def find_item(self, description: str) -> Item:
        """Find an item by description"""

        return next((item for item in self.items if item.description == description), None)

$ pylint issue1158.py

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

Without the Item dataclass, I get E0602: Undefined variable 'Item' (undefined-variable) but not the no-member errors.

[yellowhat]

Just tried on a archlinux podman image:

# pylint --version
pylint 2.10.2
astroid 2.7.3
Python 3.9.6 (default, Jun 30 2021, 10:22:16)
[GCC 11.1.0]
# cat a.py
from dataclasses import field
from typing import List
from pydantic.dataclasses import dataclass


@dataclass
class Item:
    description: str


@dataclass
class Case:
    """Case class (group Item)"""

    name: str
    irr: float = 0
    items: List[Item] = field(default_factory=lambda: [])

    def add_item(self, item: Item) -> None:
        """Add an item to the item list."""

        self.items.append(item)

    def find_item(self, description: str) -> Item:
        """Find an item by description"""

        return next((item for item in self.items if item.description == description), None)

# pylint a.py
************* Module a
a.py:28:0: C0305: Trailing newlines (trailing-newlines)
a.py:1:0: C0114: Missing module docstring (missing-module-docstring)
a.py:7:0: C0115: Missing class docstring (missing-class-docstring)
a.py:22:8: E1101: Instance of 'Field' has no 'append' member (no-member)
a.py:27:38: E1133: Non-iterable value self.items is used in an iterating context (not-an-iterable)

------------------------------------------------------------------
Your code has been rated at 0.00/10 (previous run: 0.00/10, +0.00)

[yellowhat]

Can this be reopen?

Thanks

[Pierre-Sassoulas]

Did you try with the latest pylint ? I can't reproduce on the latest main branch.

[yellowhat]

Yes, as you can see above I am using pylint 2.10.2 and astroid 2.7.3.
david-yz-liu's output above seems a bit strange as it is missing:

• Missing module docstring (missing-module-docstring)
• Missing class docstring (missing-class-docstring) for the class Item

[Pierre-Sassoulas]

Probably launched from pylint git directory using this pylintrc: https://github.com/PyCQA/pylint/blob/main/pylintrc

[yellowhat]

Does this mean the the git (unreleased) version of pylint has been used?

[Pierre-Sassoulas]

Yes that's what I meant by "latest main branch". You can try yourself with : pip install git+git://github.com/PyCQA/pylint.git@main#egg=pylint -U (Edit: there was a typo in the branch name)

[yellowhat]

Ok same error with the current git version:

# pip install git+git://github.com/PyCQA/pylint.git@main#egg=pylint -U
Collecting pylint
  Cloning git://github.com/PyCQA/pylint.git (to revision main) to /tmp/pip-install-6ytr2665/pylint_a321578df83445848ce2e945826f1f36
  Running command git clone -q git://github.com/PyCQA/pylint.git /tmp/pip-install-6ytr2665/pylint_a321578df83445848ce2e945826f1f36
Collecting platformdirs>=2.2.0
  Downloading platformdirs-2.3.0-py3-none-any.whl (13 kB)
Collecting astroid<2.8,>=2.7.3
  Downloading astroid-2.7.3-py3-none-any.whl (240 kB)
     |████████████████████████████████| 240 kB 8.8 MB/s
Collecting isort<6,>=4.2.5
  Downloading isort-5.9.3-py3-none-any.whl (106 kB)
     |████████████████████████████████| 106 kB 19.7 MB/s
Collecting mccabe<0.7,>=0.6
  Downloading mccabe-0.6.1-py2.py3-none-any.whl (8.6 kB)
Requirement already satisfied: toml>=0.7.1 in /usr/lib/python3.9/site-packages (from pylint) (0.10.2)
Requirement already satisfied: typing-extensions>=3.10.0 in /usr/lib/python3.9/site-packages (from pylint) (3.10.0.2)
Collecting lazy-object-proxy>=1.4.0
  Downloading lazy_object_proxy-1.6.0-cp39-cp39-manylinux1_x86_64.whl (57 kB)
     |████████████████████████████████| 57 kB 6.3 MB/s
Collecting wrapt<1.13,>=1.11
  Downloading wrapt-1.12.1.tar.gz (27 kB)
Requirement already satisfied: setuptools>=20.0 in /usr/lib/python3.9/site-packages (from astroid<2.8,>=2.7.3->pylint) (57.4.0)
Using legacy 'setup.py install' for pylint, since package 'wheel' is not installed.
Using legacy 'setup.py install' for wrapt, since package 'wheel' is not installed.
Installing collected packages: wrapt, lazy-object-proxy, platformdirs, mccabe, isort, astroid, pylint
    Running setup.py install for wrapt ... done
    Running setup.py install for pylint ... done
Successfully installed astroid-2.7.3 isort-5.9.3 lazy-object-proxy-1.6.0 mccabe-0.6.1 platformdirs-2.3.0 pylint-2.10.3.dev0 wrapt-1.12.1
# pylint --version
pylint 2.10.3-dev0
astroid 2.7.3
Python 3.9.6 (default, Jun 30 2021, 10:22:16)
[GCC 11.1.0]
# cat a.py
from dataclasses import field
from typing import List
from pydantic.dataclasses import dataclass


@dataclass
class Item:
    description: str


@dataclass
class Case:
    """Case class (group Item)"""

    name: str
    irr: float = 0
    items: List[Item] = field(default_factory=lambda: [])

    def add_item(self, item: Item) -> None:
        """Add an item to the item list."""

        self.items.append(item)

    def find_item(self, description: str) -> Item:
        """Find an item by description"""

        return next((item for item in self.items if item.description == description), None)

# pylint a.py
************* Module a
/a.py:28:0: C0305: Trailing newlines (trailing-newlines)
/a.py:1:0: C0114: Missing module docstring (missing-module-docstring)
/a.py:7:0: C0115: Missing class docstring (missing-class-docstring)
/a.py:22:8: E1101: Instance of 'Field' has no 'append' member (no-member)
/a.py:27:38: E1133: Non-iterable value self.items is used in an iterating context (not-an-iterable)

------------------------------------------------------------------
Your code has been rated at 0.00/10 (previous run: 0.00/10, +0.00)

This has been run in a fresh archlinux container, just installed python-pip, python-pydantic and git.

[david-yz-liu]

Okay, I can replicate this using pydantic v1.6.2 but not 1.8.2 or 1.7.4. To confirm, @yellowhat can you please check what version of pydantic you are currently using?

[yellowhat]

I am using:

import pydantic
pydantic.VERSION
'1.8.2'

[DanielNoord]

I found why @david-yz-liu couldn't reproduce this by running pylint a.py.
You need to add the --extension-pkg-whitelist="pydantic" flag in order for it to work fail. See:

❯ cat test.py
from dataclasses import field
from typing import List

from pydantic.dataclasses import dataclass


@dataclass
class Item:
    description: str


@dataclass
class Case:
    """Case class (group Item)"""

    name: str
    irr: float = 0
    items: List[Item] = field(default_factory=lambda: [])

    def add_item(self, item: Item) -> None:
        """Add an item to the item list."""

        self.items.append(item)

    def find_item(self, description: str) -> Item:
        """Find an item by description"""

        return next((item for item in self.items if item.description == description), None)

❯ pylint --extension-pkg-whitelist="pydantic" test.py
************* Module test
test.py:23:8: E1101: Instance of 'Field' has no 'append' member (no-member)
test.py:28:38: E1133: Non-iterable value self.items is used in an iterating context (not-an-iterable)

------------------------------------------------------------------
Your code has been rated at 2.31/10 (previous run: 2.31/10, +0.00)

❯ pylint test.py

-------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 2.31/10, +7.69)

This is with pydantic==1.8.2. Not sure if this gives any immediate hints as to the source of the problem, but should at least make it possible to reproduce.
I'm guessing @yellowhat has this flag in their pylint.rc and that's why it is not showing up in their shell output.

[yellowhat]

@DanielNoord I have not setup any pylint.rc, all the test above were done using a fresh archlinux container, install pydantic and pylint@git and run the example code.

[yellowhat]

Hi,
I have noticed that new code has been merged, so I tried again:

$ pip install git+git://github.com/PyCQA/pylint.git@main#egg=pylint -U
Collecting pylint
  Cloning git://github.com/PyCQA/pylint.git (to revision main) to /tmp/pip-install-q3y0k585/pylint_125c375d4e0e416186ea47bfa922181e
  Running command git clone -q git://github.com/PyCQA/pylint.git /tmp/pip-install-q3y0k585/pylint_125c375d4e0e416186ea47bfa922181e
Collecting platformdirs>=2.2.0
  Downloading platformdirs-2.3.0-py3-none-any.whl (13 kB)
Collecting astroid<2.9,>=2.8.0
  Downloading astroid-2.8.0-py3-none-any.whl (242 kB)
     |████████████████████████████████| 242 kB 10 kB/s
Collecting isort<6,>=4.2.5
  Downloading isort-5.9.3-py3-none-any.whl (106 kB)
     |████████████████████████████████| 106 kB 16.8 MB/s
Collecting mccabe<0.7,>=0.6
  Downloading mccabe-0.6.1-py2.py3-none-any.whl (8.6 kB)
Requirement already satisfied: toml>=0.7.1 in /usr/lib/python3.9/site-packages (from pylint) (0.10.2)
Requirement already satisfied: typing-extensions>=3.10.0 in /usr/lib/python3.9/site-packages (from pylint) (3.10.0.2)
Collecting wrapt<1.13,>=1.11
  Downloading wrapt-1.12.1.tar.gz (27 kB)
Requirement already satisfied: setuptools>=20.0 in /usr/lib/python3.9/site-packages (from astroid<2.9,>=2.8.0->pylint) (57.4.0)
Collecting lazy-object-proxy>=1.4.0
  Downloading lazy_object_proxy-1.6.0-cp39-cp39-manylinux1_x86_64.whl (57 kB)
     |████████████████████████████████| 57 kB 7.5 MB/s
Using legacy 'setup.py install' for pylint, since package 'wheel' is not installed.
Using legacy 'setup.py install' for wrapt, since package 'wheel' is not installed.
Installing collected packages: wrapt, lazy-object-proxy, platformdirs, mccabe, isort, astroid, pylint
    Running setup.py install for wrapt ... done
    Running setup.py install for pylint ... done
Successfully installed astroid-2.8.0 isort-5.9.3 lazy-object-proxy-1.6.0 mccabe-0.6.1 platformdirs-2.3.0 pylint-2.11.2.dev0 wrapt-1.12.1
$ pylint --version
pylint 2.11.2-dev0
astroid 2.8.0
Python 3.9.7 (default, Aug 31 2021, 13:28:12)
[GCC 11.1.0]
$ cat a.py
from dataclasses import field
from typing import List
from pydantic.dataclasses import dataclass


@dataclass
class Item:
    description: str


@dataclass
class Case:
    """Case class (group Item)"""

    name: str
    irr: float = 0
    items: List[Item] = field(default_factory=lambda: [])

    def add_item(self, item: Item) -> None:
        """Add an item to the item list."""

        self.items.append(item)

    def find_item(self, description: str) -> Item:
        """Find an item by description"""

        return next((item for item in self.items if item.description == description), None)
$ pylint a.py
************* Module a
/a.py:28:0: C0305: Trailing newlines (trailing-newlines)
/a.py:1:0: C0114: Missing module docstring (missing-module-docstring)
/a.py:7:0: C0115: Missing class docstring (missing-class-docstring)
/a.py:22:8: E1101: Instance of 'Field' has no 'append' member (no-member)
/a.py:27:38: E1133: Non-iterable value self.items is used in an iterating context (not-an-iterable)

-----------------------------------
Your code has been rated at 0.00/10

still no luck.
Can we reopen the bug?

Thanks

[and3rson]

I can reproduce this as well:

$ python3 -m pipdeptree -p pylint
pylint==2.15.3
  - astroid [required: >=2.12.10,<=2.14.0-dev0, installed: 2.12.13]
    - lazy-object-proxy [required: >=1.4.0, installed: 1.9.0]
    - typing-extensions [required: >=3.10, installed: 4.4.0]
    - wrapt [required: >=1.11,<2, installed: 1.14.1]
  - dill [required: >=0.2, installed: 0.3.6]
  - isort [required: >=4.2.5,<6, installed: 5.10.1]
  - mccabe [required: >=0.6,<0.8, installed: 0.7.0]
  - platformdirs [required: >=2.2.0, installed: 2.6.2]
  - tomli [required: >=1.1.0, installed: 2.0.1]
  - tomlkit [required: >=0.10.1, installed: 0.11.6]
  - typing-extensions [required: >=3.10.0, installed: 4.4.0]

$ python3 -m pipdeptree -p pydantic
pydantic==1.10.2
  - typing-extensions [required: >=4.1.0, installed: 4.4.0]

class Foo(BaseModel):
    events: List[Union[int, str]] = Field(default_factory=list)

    def bar(self):
        self.events.append(42)  # E1101: Instance of 'FieldInfo' has no 'append' member (no-member)

EDIT: This seems to reproduce only with non-binary version of pydantic (pip install pydantic --no-binary pydantic). When switching back to default binary version of the package (pip install pydantic), the error is gone.

[Pierre-Sassoulas]

Please open a new bug issue, I appreciate the effort to not create a duplicate but in order to reopen I'd like to reproduce and I if I don't have the time the issue is closed so it's not going to get any attention.