Question

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

（这与我在How to create an ical duration field in Django?上的问题相关）

这是我的方法：

谢谢bakkal和Pol。以下是我提出的建议。

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)

它适用于以下模型：

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'

这让我很困惑......似乎python认为我的字段是前一个字段的属性，但只有它是CharField。有什么想法吗？

Answer 1

我是傻瓜。问题是我将模型命名为duration.py，因此与“duration”字段存在命名冲突。我重命名了文件，但它确实有效。

Answer 2

更改模型后是否运行了./manage syncdb？

如果您决定更改模型，则不会更新当前数据库。唯一的方法是重置它，然后运行syncdb。

如果你正在使用SQLite - 只需删除db文件，运行syncdb，它将生成一个包含更新模型的数据库。注意，它会删除所有现有记录！

自定义Django模型字段中的“对象没有属性”

2 个答案: