如何编写单元测试以检查Django模型形式是否有效？ [英] How can I write a unittest to check that a django model form is valid?

问题描述

我正在尝试测试模型表单是否有效。

I am trying to test that a model form is valid.

在测试功能中，我创建了两个自定义表单模型。我添加数据以填写表单的必填字段。

In the test function, I create the two models that feature in my custom form. I add the data to fill the form's required fields.

当我运行测试并在表单上调用 is_valid（）时，测试失败，并且表单给出了错误，我添加的选项是不是可用选项之一。这向我表明我已将 Option 实例错误地添加到表单或测试中。我不确定如何使用。

When I run the tests and call is_valid() on the form, the test fails and the form gives the error that the option that I have added is not one of the available choices. This suggests to me that I have incorrectly added the Option instance to the form or to the test. I am unsure how.

如何使模型形式对测试有效？

How can I make the model form valid for the test?

tests.py

    def test_valid_data(self):
        question_1 = Question(
            question_text='What is the width of the telephone?',
            date_published=timezone.now(),
            collection=Collection.objects.create()
        )
        question_1.save()
        option_1 = question_1.options.create(
            question=question_1,
            option_text='Five centimetres'
        )
        option_1.save()
        data = {'question_text': question_1.question_text, 'selected_option': option_1.option_text,}
        form = QuestionForm(data=data)
        print(form)
        self.assertTrue(form.is_valid())

forms.py

class QuestionForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(QuestionForm, self).__init__(*args, **kwargs)
        self.fields['selected_option'] = forms.ChoiceField(
            choices=[
                (f'{option.pk}', f'{option}')
                for option in Option.objects.filter(question_id=self.instance.pk)
            ],
            widget=RadioSelect,
            required=True,
            error_messages={
                'required': 'The question form lacks a selected_option'
            }

        )

    class Meta:
        model = Question
        fields = ('question_text',)
        labels = {
            'question_text': ''
        }
        widgets = {
            'question_text': forms.Textarea(attrs={'cols': '40', 'rows': '2'})
        }

models.py

class Question(models.Model):
    question_text = models.CharField(max_length=400)
    collection = models.ForeignKey(Collection, on_delete=models.PROTECT, default=None)
    date_published = models.DateTimeField('date published')

    def __str__(self) -> str:
        return self.question_text


class Option(models.Model):
    option_text = models.CharField(max_length=400)
    question = models.ForeignKey(Question, on_delete=models.CASCADE)

    class Meta:
        default_related_name = 'options'

    def __str__(self) -> str:
        return self.option_text

预期： is_valid（） -> True

实际值： is_valid（）-> 错误

推荐答案

问题是由您在 QuestionForm .__ init __ 中定义选项的方式引起：

The issue is caused by the way that you have defined choices in QuestionForm.__init__:

choices=[
    (f'{option.pk}', f'{option}')
    for option in Option.objects.filter(question_id=self.instance.pk)
],

您已根据以下内容创建了个选择与 QuestionForm 相关的 Question 实例的 pk 发起。

You have created choices based on the pk of the Question instance related with the QuestionForm you initiate.

在您的测试中（以及在管理员中），表单不受任何<$通过输入
form = QuestionForm（data = data）初始化表单时，出现c $ c>问题。

In your test (and also in the admin), the form is not bound to any instance of Question when you initiate the form by entering form = QuestionForm(data=data).

因此，查询 Option.objects.filter（question_id = self.instance.pk）返回 None ，因为 self.instance.pk 是 None 。

Consequently, the query Option.objects.filter(question_id=self.instance.pk) returns None because self.instance.pk is None.

因此，在保存 QuestionForm 之前，您会收到错误消息，因为 choices = []

Therefore, you receive the error before saving the QuestionForm because choices = []

如果您按下保存按钮或执行 form.save（）。

The query would return results if you pressed the "Save" button or if you do a form.save().

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