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如何使用django orm进行此特殊的许多字段验证?

many-to-many validation django

Bite code · 技术社区 · 15 年前

我有以下型号:

class Step(models.Model):

    order = models.IntegerField()
    latitude = models.FloatField()
    longitude = models.FloatField()
    date = DateField(blank=True, null=True)


class Journey(models.Model):

    boat = models.ForeignKey(Boat)
    route = models.ManyToManyField(Step)
    departure = models.ForeignKey(Step, related_name="departure_of", null=True)
    arrival = models.ForeignKey(Step, related_name="arrival_of", null=True)

我想执行以下检查:

        # If a there is less than one step, raises ValidationError.

        routes = tuple(self.route.order_by("date"))

        if len(routes) <= 1:
            raise ValidationError("There must be at least two setps in the route")

        # save the first and the last step as departure and arrival
        self.departure = routes[0]
        self.arrival = routes[-1]

        # departure and arrival must at least have a date
        if not (self.departure.date or self.arrival.date):
            raise ValidationError("There must be an departure and an arrival date. "
                                  "Please set the date field for the first and last Step of the Journey")

        # departure must occurs before arrival    
        if not (self.departure.date > self.arrival.date):
            raise ValidationError("Departure must take place the same day or any date before arrival. "
                                  "Please set accordingly the date field for the first and last Step of the Journey")

我试图通过超载来做到这一点。 save() . 不幸的是, Journey.route 在中为空 保存() . 另外, Journey.id 还不存在。我没试过 django.db.models.signals.post_save 但是假设它会失败,因为 旅程.路线 也是空的(还是什么时候填的?).我看到一个解决方案 django.db.models.signals.m2m_changed 但是有很多步骤(几千个),我想避免对每一个步骤执行操作。

2 回复 | 直到 15 年前

knutin 15 年前

如果你在经营最新最棒的Django,看看这个 http://docs.djangoproject.com/en/dev/ref/models/instances/#id1

基本上,可以用与表单相同的方式验证模型。虽然我自己从来没有用过它,但它看起来很适合你想做的事情。

Bite code 15 年前

最后,我必须为创建这个对象的每个表单编写一个验证。克努丁的解决方案会很好,但我运行django 1.1。

不管怎样,Django让你很容易过载管理验证,所以我做到了:

class JourneyAdminForm(forms.ModelForm):

    class Meta:
        model = Journey

    def clean_route(self):
        """
            Ensure a Journey includes at least 2 dated steps, 
            departure starting before arrival.
        """

        # must use getlist as self.data is not a dict but a querydict
        routes = self.data.getlist("route")

        if len(routes) <= 1:
            raise ValidationError("There must be at least two setps in the route")

        departure = Step.objects.get(id=routes[0])
        arrival = Step.objects.get(id=routes[-1])
        self.data["departure"] = departure.id
        self.data["arrival"] = arrival.id


        if not (departure.date and arrival.date):
            raise ValidationError("There must be an departure and an arrival date. "
                                  "Please set the date field for the first and last Step of the Journey")

        if not (departure.date <= arrival.date):
            raise ValidationError("Departure must take place the same day or any date before arrival. "
                                  "Please set accordingly the date field for the first and last Step of the Journey")

        return self.cleaned_data["route"]

class JourneyAdmin(admin.ModelAdmin):

    exclude = ("arrival", "departure")
    form = JourneyAdminForm

admin.site.register(Journey, JourneyAdmin)

另外,在提交表单时,validationError消息将显示为用户的反馈。