Django 为 FileField 添加前缀

Question

我有一个模型可以接收多个 pdf 文件。当用户上传这些文件时，我希望每个文件都用前缀和一些随机字符重命名。我可以将 upload_to 分配给可调用的函数，例如：

class Order(models.Model):
    invoice_file = models.FileField(upload_to=invoice_file_name)
    purchase_order_file = models.FileField( upload_to=po_file_name)
    payment_file = models.FileField( upload_to=payment_file_name)

def invoice_file_name(instance, file_name):
    return 'inv_' + str(uuid.uuid4()) + '.pdf'

def po_file_name(instance, file_name):
    return 'po_' + str(uuid.uuid4()) + '.pdf'

def payment_file_name(instance, file_name):
    return 'pmt_' + str(uuid.uuid4()) + '.pdf'

有没有办法概括这些 upload_to 函数，以便我可以在 FileField 定义中传递前缀？

尝试：

我试图通过创建一个扩展 FileField 的自定义文件字段来解决这个问题

class CustomFileField(models.FileField):
    def __init__(self, file_prefix, **kwargs):
        self.file_prefix = file_prefix
        # print(kwargs)
        super().__init__(upload_to=self.custom_upload_to, **kwargs)

    def custom_upload_to(self, file_name):
        return self.file_prefix + str(uuid.uuid4()) + '.pdf' 


class Order(models.Model):
    invoice_file = CustomFileField(file_prefix='inv_')
    purchase_order_file = CustomFileField(file_prefix='po_')
    payment_file = CustomFileField(file_prefix='pmt_')

但是，迁移失败。其中一个错误是

TypeError: __init__() got multiple values for keyword argument 'upload_to'

不太清楚发生了什么，但我查看了迁移文件，它似乎在调用这个：

migrations.CreateModel(
    name='Order',
    fields=[
        ('invoice_file', CustomFileField(blank=True, null=True, upload_to='')
        ...
    ])

这是对 FileField 进行子类化的错误方式吗？

Answer 1

你可以不用CustomFileField 而是用@deconstructible 来做到这一点

from django.utils.deconstruct import deconstructible
from django.db import models


@deconstructible
class file_prefix(object):
    def __init__(self, prefix):
        self.prefix = prefix

    def __call__(self, instance, filename):
        ext = filename.split('.')[-1] # PDF if you want
        filename = "%s%s.%s" % (self.prefix,str(uuid.uuid4()), ext)
        return filename

例如，调用upload_to时默认发送文件名，所以我们只发送前缀。

class Order(models.Model):
    invoice_file = models.FileField(upload_to=file_prefix('inv_'))
    purchase_order_file = models.FileField(upload_to=file_prefix('po_'))
    payment_file = models.FileField(upload_to=file_prefix('pmt_'))

Answer 2

这是有效的：

class CustomFileField(models.FileField):
    def __init__(self, file_prefix = '', null=True, blank=True, upload_to='', **kwargs):
        self.file_prefix = file_prefix
        super().__init__(upload_to=self.custom_upload_to, **kwargs)

    def custom_upload_to(self, instance, file_name):
        return self.file_prefix + str(uuid.uuid4()) + '.pdf' 


class Order(models.Model):
    invoice_file = CustomFileField(file_prefix='inv_')
    purchase_order_file = CustomFileField(file_prefix='po_')
    payment_file = CustomFileField(file_prefix='pmt_')

迁移序列化程序似乎要查找 3 个参数：null、blank 和 upload_to，所以我需要在我的 CustomFileField 初始化函数中包含这些参数。