“对象没有属性”在自定义Django模型字段 [英] "object has no attribute" in custom Django model field

问题描述

我正在尝试创建一个Django模型字段，该字段表示HTML中的文本输入字段的日，小时，分钟和秒的持续时间，并使用ical格式（RFC5545）将持续时间存储在数据库中。

I am trying to create a Django model field that represents a duration with days, hours, minutes and seconds text input fields in the HTML, and stores the duration in the db using the ical format (RFC5545).

（这与我在如何在Django中创建ical持续时间字段？）

这是我的方法：

谢谢bakkal和Pol。下面是我想出来的从django.db导入模型

Thanks bakkal and Pol. Below is what I came up with.

from django.db import models
from icalendar.prop import vDuration
from django.forms.widgets import MultiWidget
from django.forms import TextInput, IntegerField
from django.forms.util import flatatt
from django.forms.fields import MultiValueField
from django.utils.encoding import force_unicode
from django.utils.safestring import mark_safe
from django.utils.text import capfirst
from django.utils.translation import ugettext_lazy as _
from django.core import validators
from datetime import timedelta

def is_int(s):
    try: 
        int(s)
        return True
    except ValueError:
        return False

class Widget_LabelInputField(TextInput):
    """
    Input widget with label
    """
    input_type="numbers"
    def __init__(self, labelCaption, attrs=None):
        self.labelCaption = labelCaption
    super(Widget_LabelInputField, self).__init__(attrs)

    def _format_value(self, value):
        if is_int(value):
            return value
        return '0'

    def render(self, name, value, attrs=None):
        if value is None:
            value = '0'
        final_attrs = self.build_attrs(attrs, type=self.input_type, name=name)
        if value != '':
            # Only add the 'value' attribute if a value is non-empty.
            final_attrs['value'] = force_unicode(self._format_value(value))
        if (self.labelCaption):
        typeString = self.labelCaption + ': '
        else:
            typeString = ''           
        return mark_safe(u'' + typeString + '<input%s style=\'width: 30px; margin-right: 20px\'/>' % flatatt(final_attrs))



class Widget_DurationField(MultiWidget):
    """
    A Widget that splits duration input into two <input type="text"> boxes.
    """

    def __init__(self, attrs=None):
        widgets = (Widget_LabelInputField(labelCaption='days', attrs=attrs),
                   Widget_LabelInputField(labelCaption='hours', attrs=attrs),
                   Widget_LabelInputField(labelCaption='minutes', attrs=attrs),
                   Widget_LabelInputField(labelCaption='seconds', attrs=attrs)
                   )
        super(Widget_DurationField, self).__init__(widgets, attrs)

    def decompress(self, value):
        if value:
            duration = vDuration.from_ical(value)
            return [str(duration.days), str(duration.seconds // 3600), str(duration.seconds % 3600 // 60), str(duration.seconds % 60)]
        return [None, None, None, None]



class Forms_DurationField(MultiValueField):
    widget = Widget_DurationField
    default_error_messages = {
        'invalid_day': _(u'Enter a valid day.'),
        'invalid_hour': _(u'Enter a valid hour.'),
        'invalid_minute': _(u'Enter a valid minute.'),
        'invalid_second': _(u'Enter a valid second.')
    }

    def __init__(self, *args, **kwargs):
        errors = self.default_error_messages.copy()
        if 'error_messages' in kwargs:
            errors.update(kwargs['error_messages'])
        fields = (
            IntegerField(min_value=-9999, max_value=9999,
                      error_messages={'invalid': errors['invalid_day']},),
            IntegerField(min_value=-9999, max_value=9999,
                      error_messages={'invalid': errors['invalid_hour']},),
            IntegerField(min_value=-9999, max_value=9999,
                      error_messages={'invalid': errors['invalid_minute']},),
            IntegerField(min_value=-9999, max_value=9999,
                      error_messages={'invalid': errors['invalid_second']},),
        )
        super(Forms_DurationField, self).__init__(fields, *args, **kwargs)

    def compress(self, data_list):
        if data_list:
            if data_list[0] in validators.EMPTY_VALUES:
                raise ValidationError(self.error_messages['invalid_day'])
            if data_list[1] in validators.EMPTY_VALUES:
                raise ValidationError(self.error_messages['invalid_hour'])
            if data_list[2] in validators.EMPTY_VALUES:
                raise ValidationError(self.error_messages['invalid_minute'])
            if data_list[3] in validators.EMPTY_VALUES:
                raise ValidationError(self.error_messages['invalid_second'])

            return vDuration(timedelta(days=data_list[0],hours=data_list[1],minutes=data_list[2],seconds=data_list[3]))
        return None




class Model_DurationField(models.Field):
    description = "Duration"

    def __init__(self, *args, **kwargs):
        super(Model_DurationField, self).__init__(*args, **kwargs)

    def db_type(self, connection):
        return 'varchar(255)'

    def get_internal_type(self):
        return "Model_DurationField"

    def to_python(self, value):
        if isinstance(value, vDuration) or value is None:
            return value

        return vDuration.from_ical(value) 

    def get_prep_value(self, value):
        return value.to_ical() 

    def formfield(self, **kwargs):
        defaults = {
            'form_class': Forms_DurationField,
            'required': not self.blank,
            'label': capfirst(self.verbose_name),
            'help_text': self.help_text}
        defaults.update(kwargs)
        return super(Model_DurationField, self).formfield(**defaults)

它适用于以下型号： p>

It works in the following Model:

class TestModel(models.Model):
    ID = models.CharField(max_length=255)
    start = models.DateTimeField(null=True)
    #duration = models.CharField(max_length=255,null=True) commented out
    otherDuration = duration.Model_DurationField(null=True)

但不在这一个：

class TestModel(models.Model):
    ID = models.CharField(max_length=255)
    start = models.DateTimeField(null=True)
    duration = models.CharField(max_length=255,null=True)  # not commented out
    otherDuration = duration.Model_DurationField(null=True)

我收到以下错误：

File "/somepath/models.py", line 5, in TestModel
    otherDuration = duration.Model_DurationField(null=True)
AttributeError: 'CharField' object has no attribute 'Model_DurationField'

$ b $这个谜我...似乎python认为我的字段是上一个字段的属性，但只有当它是一个CharField。任何想法？

That puzzles me... it seems that python considers my field to be an attribute of the previous field, but only if it is a CharField. Any ideas?

推荐答案

我很愚蠢问题是我命名了模型定义为duration.py的文件，所以与duration字段有一个命名冲突。我将该文件重新命名，并且正常工作。

I was stupid. The problem was that I named the file where the model was defined duration.py, so there was a naming conflict with the "duration" field. I renamed the file and it worked.

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