Django源码解析|Migrations文件的生成

from django.db import models


class Post(models.Model):
    title = models.CharField(max_length=100)
    created_time = models.DateTimeField(auto_now_add=True)

from django.db import migrations, models


class Migration(migrations.Migration):

    initial = True

    dependencies = [
    ]

    operations = [
        migrations.CreateModel(
            name='Post',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('title', models.CharField(max_length=100)),
                ('created_time', models.DateTimeField(auto_now_add=True)),
            ],
        ),
    ]

import inspect


class CreateModel:
    def __init__(self, name, age=20):
        self.name = name
        self.age = age

    def deconstruct(self):
        kwargs = {
            'name': self.name,
            'age': self.age,
        }
        return (
            self.__class__.__qualname__,
            [self.name],
            kwargs
        )


def get_func_args(func):
    # django/utils/inspect.py
    sig = inspect.signature(func)
    return [
        arg_name for arg_name, param in sig.parameters.items()
        if param.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD
    ]


def rewrite(foo):
    name, args, kwargs = foo.deconstruct()
    operation_args = get_func_args(foo.__init__)
    buf = []
    buf.append(f'{name}(')
    for i, arg in enumerate(args):
        arg_value = arg
        arg_name = operation_args[i]
        buf.append(f'"{arg_value}",')

    i = len(args)
    for arg_name in operation_args[i:]:
        if arg_name in kwargs:
            arg_value = kwargs[arg_name]
            buf.append(f'{arg_name}={arg_value},')
    buf.append(')')
    print('\n'.join(buf))


if __name__ == '__main__':
    # 把下面的定义转写到文件中
    foo = CreateModel(
        'the5fire',
        age=30
    )

    rewrite(foo)