Django：在 UpdateView 中覆盖 get_queryset()答案

【问题标题】：Django: Override get_queryset() in UpdateViewDjango：在 UpdateView 中覆盖 get_queryset()
【发布时间】：2020-10-07 16:27:24
【问题描述】：

“项目”模型

class Project(models.Model):
    company = models.ForeignKey('projects.Company', on_delete=models.PROTECT, related_name='projects')

    title = models.CharField('Project title', max_length=128)
    start_date = models.DateField('Project start date', blank=True, null=True)
    end_date = models.DateField('Project end date', blank=True, null=True)

    estimated_design = models.DecimalField('Estimated design hours', max_digits=5, decimal_places=1,
                                           validators=[MinValueValidator(Decimal('0.01'))])
    actual_design = models.DecimalField('Actual design hours', default=0, decimal_places=1, max_digits=5,
                                        validators=[MinValueValidator(Decimal('0.01'))])

    estimated_development = models.DecimalField('Estimated development hours', max_digits=5, decimal_places=1,
                                                validators=[MinValueValidator(Decimal('0.01'))])
    actual_development = models.DecimalField('Actual development hours', default=0, decimal_places=1, max_digits=5,
                                             validators=[MinValueValidator(Decimal('0.01'))])

    estimated_testing = models.DecimalField('Estimated testing hours', max_digits=5, decimal_places=1,
                                            validators=[MinValueValidator(Decimal('0.01'))])
    actual_testing = models.DecimalField('Actual testing hours', default=0, decimal_places=1, max_digits=5,
                                         validators=[MinValueValidator(Decimal('0.01'))])

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('project-update', kwargs={'pk': self.pk, 'slug': slugify(self.title)})

    @property
    def has_ended(self):
        return self.end_date is not None and self.end_date < timezone.now().date()

    @property
    def total_estimated_hours(self):
        return self.estimated_design + self.estimated_development + self.estimated_testing

    @property
    def total_actual_hours(self):
        return self.actual_design + self.actual_development + self.actual_testing

    @property
    def is_over_budget(self):
        return self.total_actual_hours > self.total_estimated_hours

我的 ModelForm 类

class ProjectForm(ModelForm):

    class Meta:
        model = Project
        fields = ['actual_design', 'actual_development', 'actual_testing']

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.helper = FormHelper()
        self.helper.add_input(Submit('submit', 'UPDATE'))

我的 UpdateView 类

class ProjectUpdateView(LoginRequiredMixin, UpdateView):
    model = Project
    form_class = ProjectForm
    success_url = reverse_lazy('dashboard')

目前，我的 ProjectUpdateView 类正在替换我的 ProjectForm 类上指示的十进制值。我应该通过表格上指示的数字来增加这些数值，而不是替换它们。据我了解，这可以通过覆盖我的 ProjectUpdateView 类中的 get_queryset() 来实现。我该如何实现呢？

【问题讨论】：

标签： django django-views overriding modelform

【解决方案1】：

为了增加值，您将值 x 替换为 <i>x</i> + F(<i>'field_name'</i>)，您可以通过覆盖 form_valid 方法来实现：

from django.db.models import F

class ProjectUpdateView(LoginRequiredMixin, UpdateView):
    model = Project
    form_class = ProjectForm
    success_url = reverse_lazy('dashboard')

    def form_valid(self, form):
        form.instance.actual_design += F('actual_design')
        form.instance.actual_development += F('actual_development')
        form.instance.actual_testing += F('actual_testing')
        return super().form_valid(form)

【讨论】：