在Python Django Crispy表单中处理异常

2024-09-30 02:15:14 发布

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我是Python3.8.2/Django 3.1.1的新手，我正在尝试找出向模型添加规则的正确方法，以便从表单和web服务调用这些规则。我遇到的问题是，一些错误没有被正确捕获，它们会生成500个错误

这是我的初始模型：

class TotalPoints(TimeStampedModel):
    course = models.ForeignKey(Course, on_delete=models.CASCADE, related_name='TotalPoints_Course', null=False, blank=False, verbose_name='Curso')
    kit = models.ForeignKey(Kit, on_delete=models.CASCADE, related_name='TotalPoints_Kit', null=False, blank=False, verbose_name='Kit')
    bought = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Comprados')
    assigned = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Asignados')
    available = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Disponibles')
    class Meta:
        db_table = 'app_totalpoints'
        constraints = [
            models.UniqueConstraint(fields=['course','kit'], name='app_totalpoints.course-kit')
        ]

字段声明为正值IntegerField以避免负值

这是我的表单和CreateView

class TotalPointsForm(forms.ModelForm):
    class Meta:
        model = TotalPoints
        fields = ['id', 'course', 'kit', 'available', 'bought', 'assigned']

class TotalPointsCreateView(CreateView):
    model = TotalPoints
    form_class = TotalPointsForm
    template_name = 'app/form_base.html'
    success_url='../list/'

这是我的模板：

{# app/templates/app/form_base.html #}
{% load crispy_forms_tags %}
<!doctype html>
<html lang="en">
    <head lang="es">
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
        <link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.22/css/jquery.dataTables.css">
        <title>{% block page_title %}{% endblock %}</title>
    </head>
    <body>
        <div class="container-fluid">
            <div class="jumbotron">
                <h1 class="display-4">{% block form_title %}{% endblock %}</h1>
                <p class="lead">{% block form_subtitle %}{% endblock %}
                {% if user.is_authenticated %}
                    ( Usuario: {{ user.get_username }} )
                {% else %}
                    ( Usuario no registrado. )
                {% endif %}
                </p>
                <hr class="my-4">
                <div id='form-errors'>{{ form_errors }}</div>
                <form method="post">
                    {% csrf_token %}
                    {{ form|crispy }}
                    <button type="submit" class="btn btn-success">Grabar</button>
                    <!-- <a class="btn btn-primary" href="../list" role="button">Cancelar</a> -->
                    <a class="btn btn-primary" href="#" onclick="location.href = document.referrer; return false;" role="button">Cancelar</a>
                </form>
            </div>
        </div>
        <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
        <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.22/js/jquery.dataTables.js"></script>
    </body>
</html>

到目前为止，一切正常，保存错误的值会在表单上返回一条消息： Negative Number Message

要实施的规则是： 可用=购买-分配 （可争议文件=Compados-Asignados）

这是我尝试的第一个版本，修改后的型号：

class TotalPoints(TimeStampedModel):
    course = models.ForeignKey(Course, on_delete=models.CASCADE, related_name='TotalPoints_Course', null=False, blank=False, verbose_name='Curso')
    kit = models.ForeignKey(Kit, on_delete=models.CASCADE, related_name='TotalPoints_Kit', null=False, blank=False, verbose_name='Kit')
    bought = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Comprados')
    assigned = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Asignados')
    available = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Disponibles')
    class Meta:
        db_table = 'app_totalpoints'
        constraints = [
            models.UniqueConstraint(fields=['course','kit'], name='app_totalpoints.course-kit')
        ]
    def save(self, *args, **kwargs):
        #AVAILABLE = BOUGHT - ASSIGNED
        self.available = self.bought - self.assigned
        super(TotalPoints, self).save(*args, **kwargs)

如果所有值均为正值，则该规则有效并正确计算可用值 Rule is working 如果Buyd为负值，则表单上会显示正确的错误，但如果可用，则会变为负值（bougth<；assigned），错误不会被捕获 enter image description here跟踪：

Traceback (most recent call last):
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
psycopg2.errors.CheckViolation: el nuevo registro para la relación «app_totalpoints» viola la restricción «check» «app_totalpoints_available_check»
DETAIL:  La fila que falla contiene (36, 2020-10-19 21:16:05.356574+00, 2020-10-20 15:57:39.007548+00, 10, 12, 23, 1, -2).


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/core/handlers/base.py", line 179, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/contrib/auth/decorators.py", line 21, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/views/generic/base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/views/generic/base.py", line 98, in dispatch
    return handler(request, *args, **kwargs)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/views/generic/edit.py", line 194, in post
    return super().post(request, *args, **kwargs)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/views/generic/edit.py", line 142, in post
    return self.form_valid(form)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/views/generic/edit.py", line 125, in form_valid
    self.object = form.save()
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/forms/models.py", line 460, in save
    self.instance.save()
  File "/home/egarza/projects/python/DjangoRESTABC/abc_project/app/models.py", line 138, in save
    super(TotalPoints, self).save(*args, **kwargs)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/base.py", line 753, in save
    self.save_base(using=using, force_insert=force_insert,
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/base.py", line 790, in save_base
    updated = self._save_table(
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/base.py", line 872, in _save_table
    updated = self._do_update(base_qs, using, pk_val, values, update_fields,
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/base.py", line 926, in _do_update
    return filtered._update(values) > 0
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/query.py", line 803, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1522, in execute_sql
    cursor = super().execute_sql(result_type)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1156, in execute_sql
    cursor.execute(sql, params)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/backends/utils.py", line 98, in execute
    return super().execute(sql, params)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/backends/utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/backends/utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/egarza/projects/python/DjangoRESTABC/django-rest-abc-env/lib/python3.8/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: el nuevo registro para la relación «app_totalpoints» viola la restricción «check» «app_totalpoints_available_check»
DETAIL:  La fila que falla contiene (36, 2020-10-19 21:16:05.356574+00, 2020-10-20 15:57:39.007548+00, 10, 12, 23, 1, -2).

我切换到pre_save using signals中的一个规则，但结果是一样的： 使用信号的版本02：

class TotalPoints(TimeStampedModel):
    course = models.ForeignKey(Course, on_delete=models.CASCADE, related_name='TotalPoints_Course', null=False, blank=False, verbose_name='Curso')
    kit = models.ForeignKey(Kit, on_delete=models.CASCADE, related_name='TotalPoints_Kit', null=False, blank=False, verbose_name='Kit')
    bought = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Comprados')
    assigned = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Asignados')
    available = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Disponibles')
    class Meta:
        db_table = 'app_totalpoints'
        constraints = [
            models.UniqueConstraint(fields=['course','kit'], name='app_totalpoints.course-kit')
        ]

@receiver(pre_save, sender=TotalPoints, dispatch_uid="totalpoints_presave")
def totalpoints_presave(sender, instance, **kwargs):
    instance.available = instance.bought - instance.assigned

那么，这些规则应该在哪里实现，以便使表单和Django能够正确地处理错误呢

添加：

我知道我正在提前计算表单以捕获错误，这是否意味着我必须在表单上复制规则并始终进行重复验证

模型上是否有一个标准事件来执行此计算？（我也通过web服务调用model，所以我需要规则是通用的）

我知道我可以使用@property，但我需要数据库上的字段，因为它稍后将被另一个进程（非Python进程）使用

我是一个老的C#/Java程序员，我可能犯了非常明显的错误，所以请教育我，不要假设我理解全部内容

先谢谢你

部分答案

我修改了Melvyns注释并重写了clean方法：

class TotalPoints(TimeStampedModel):
    course = models.ForeignKey(Course, on_delete=models.CASCADE, related_name='TotalPoints_Course', null=False, blank=False, verbose_name='Curso')
    kit = models.ForeignKey(Kit, on_delete=models.CASCADE, related_name='TotalPoints_Kit', null=False, blank=False, verbose_name='Kit')
    bought = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Comprados')
    assigned = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Asignados')
    available = models.PositiveIntegerField(default=0, null=False, blank=False, verbose_name='Disponibles')
    class Meta:
        db_table = 'app_totalpoints'
        constraints = [
            models.UniqueConstraint(fields=['course','kit'], name='app_totalpoints.course-kit')
        ]
    def clean(self):
        super().clean()
        if self.assigned > self.bought:
            #OPTION 1 Raise on the Form
            #raise ValidationError('Asignados debe ser menor o igual a Comprados')
            #OPTION 2 Raise on the field
            raise ValidationError({'assigned': 'Asignados no debe ser mayor a Comprados.'})

现在我在表单上得到了正确的错误消息，但这是验证数据的一种迂回方式： enter image description here


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1条回答
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1楼 · 发布于 2024-09-30 02:15:14

由于约束，保存数据库认为错误的内容时，会发生完整性错误。这太晚了，表单无法捕获它

ModelForms在模型上调用full_clean()，并将捕获任何要处理的验证错误，就像它是一个表单错误一样。通话顺序如下：

  1. forms.forms.Form.u是否有效（）
  2. forms.forms.Form.full_clean（）
  3. forms.models.ModelForm.\u post\u clean（）
  4. instance.full_clean（）=>；ValidationErrors转到form.errors
    1. 净土
    2. instance.clean（）
    3. 验证唯一性
  5. instance.save（）=>；下得太远，无法使气泡恢复

因此，您可以在instance.clean（）上进行验证，并确保引发ValidationErrors。相关阅读：

Form validation：

Form validation happens when the data is cleaned. If you want to customize this process, there are various places to make changes, each one serving a different purpose. Three types of cleaning methods are run during form processing

Model validation

There are three steps involved in validating a model:

Validate the model fields - Model.clean_fields() Validate the model as a whole - Model.clean() Validate the field uniqueness - Model.validate_unique()

All three steps are performed when you call a model’s full_clean() method.

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