Django中重写model_to_dict方法，兼容接口返回展示时间和外键的

from itertools import chain
import datetime
from django.db.models.fields.related import ManyToManyField, ForeignKey, OneToOneField
from django.core.files import File


def model_to_dict(instance, fields=None, exclude=None):
    """
    Return a dict containing the data in ``instance`` suitable for passing as
    a Form's ``initial`` keyword argument.

    ``fields`` is an optional list of field names. If provided, return only the
    named.

    ``exclude`` is an optional list of field names. If provided, exclude the
    named from the returned dict, even if they are listed in the ``fields``
    argument.
    """
    if instance == None:  # 若果要是过来空的值，那就直接返回了
        return
    opts = instance._meta
    data = {}
    for f in chain(opts.concrete_fields, opts.private_fields, opts.many_to_many):
        # if not getattr(f, "editable", False):
        #     continue
        print('看看F是啥：', f)
        if fields is not None and f.name not in fields:
            continue
        if exclude and f.name in exclude:
            continue
        # data[f.name] = f.value_from_object(instance)
        value = f.value_from_object(instance)
        if type(value) == datetime.datetime:
            value = value.strftime('%Y-%m-%d %H:%M:%S')
        elif type(value) == datetime.date:
            value = value.strftime('%Y-%m-%d ')
        elif type(f) == ForeignKey:  # 展示外键关联表的数据
            foreign_Key = getattr(instance, f.name)
            value = model_to_dict(foreign_Key)
        elif type(f) == OneToOneField:  # 展示一对一关联表的数据
            opneToOne_Field = getattr(instance, f.name)
            value = model_to_dict(opneToOne_Field)
        elif type(f) == ManyToManyField:  # 展示多对多的
            many_to_many__list = [model_to_dict(item) for item in value]
            value = many_to_many__list
        if isinstance(value, File):  # /XXX/XXX/a.jpg  返回文件的路径
            value = str(value)
        data[f.name] = value
    return data