如何使用Q对象在Django模型中查询float / int值或字符串？

Question

Django版本= 1.8，IDE = pycharm，python 2.7

我有一个搜索表单，我想基于与产品标题或产品描述或产品价格匹配的字符串搜索并列出模型中的item（“产品”）。

以下是views.py中我的“搜索项”部分。 我也很困惑下面的行在get_queryset函数中做什么。 干杯

   qs = super(ProductListView, self).get_queryset(*args,**kwargs)

＃

# Search inside model function
def get_queryset(self, *args, **kwargs):
    qs = super(ProductListView, self).get_queryset(*args,**kwargs)
    query = self.request.GET.get("q")
    if query:
        qs = self.model.objects.filter(

            Q(title__icontains=query) |
            Q(description__icontains=query) |
            Q(price=query)
        )
    return qs

class ProductListView(ListView):
    model = Product
    queryset=Product.objects.all()  #no need to define this as it is a default
    def get_context_data(self, *args, **kwargs):
        context = super(ProductListView, self).get_context_data(*args, **kwargs)
        return context

下面是models.py

    from django.db import models
    from django.core.urlresolvers import reverse
    from django.db.models.signals import post_save
    from django.utils.text import slugify

    # Create your models here.

    class ProductQuerySet(models.query.QuerySet):
        def active(self):
            return self.filter(active=True)


    class ProductManager(models.Manager):
        def get_queryset(self):
            return ProductQuerySet(self.model, using=self.db)

        def all(self, *args, **kwargs):
            return self.get_queryset().active()


    class Product(models.Model):
        title = models.CharField(max_length=120)
        description = models.TextField(blank=True, null=True)
        price = models.DecimalField(decimal_places=2, max_digits=10)
        active = models.BooleanField(default=True)
        objects = ProductManager()

        def __unicode__(self):
            return self.title

        def get_absolute_url(self):
            return reverse("product_detail", kwargs={"pk": self.pk})
            # OR use this- return "/product/%s"%(self.pk)


    class Variation(models.Model):
        product = models.ForeignKey(Product)  ##this means each Variation is related to single product
        title = models.CharField(max_length=120)
        price = models.DecimalField(decimal_places=2, max_digits=10)
        sale_price = models.DecimalField(decimal_places=2, max_digits=10, null=True, blank=True)
        active = models.BooleanField(default=True)
        inventory = models.IntegerField(null=True, blank=True)  # default=-1 means unlimited

        def __unicode__(self):
            return self.title

        def get_price(self):
            if self.sale_price is not None:
                return self.sale_price
            else:
                return self.price

        def get_absolute_url(self):
            return self.product.get_absolute_url()


    # for post save receiver


    def product_saved_receiver(sender, instance, created, *args, **kwargs):
        # sender=modelclass, instance=actual instance being saved,created=boolean true if record was created
        product = instance
        variations = product.variation_set.all()
        if variations.count() == 0:
            new_var = Variation()
            new_var.product = product
            new_var.title = "Default"
            new_var.price = product.price
            new_var.save()

    post_save.connect(product_saved_receiver, sender=Product)


    # product image
    # you need to install python pillow library to support.


    # it checks if file uploaded is actually an image and checks extension
    # class ProductImage(models.Model):
    #     product = models.ForeignKey(Product)
    #     image = models.ImageField(upload_to='products/') #image will be uploaded to media/mediaroot/products
    #
    #     def __unicode__(self):
    #         return self.product.title

    #slugify
    def image_upload_to(instance, filename):
        title = instance.product.title
        slug = slugify(title)
        file_extension = filename.split(".")[1]
        # or  basename,file_extension = filename.split(".")
        new_filename = "%s.%s" %(instance.id,file_extension)
        return "products/%s/%s" %(slug, filename)

    # above function changed for slugfying

    class ProductImage(models.Model):
        product = models.ForeignKey(Product)
        image = models.ImageField(upload_to=image_upload_to) #image will be uploaded to media/mediaroot/products

        def __unicode__(self):
            return self.product.title

使用上述代码，我可以根据价格搜索并列出价格，例如。 50或67.89，但无法搜索字符串并获得以下错误

http://127.0.0.1:8000/products/?q=与国王骑马

ValidationError at /products/

[u"'eric clapton riding with the king' value must be a decimal number."]

Request Method:     GET
Request URL:    http://127.0.0.1:8000/products/?q=eric%20clapton%20riding%20with%20the%20king
Django Version:     1.8.4
Exception Type:     ValidationError
Exception Value:    

[u"'eric clapton riding with the king' value must be a decimal number."]

Exception Location:     C:\Anaconda\lib\site-packages\django\db\models\fields\__init__.py in to_python, line 1602
Python Executable:  C:\Anaconda\python.exe
Python Version:     2.7.10  

Answer 1

由于价格需要一个十进制值，因此我们应该提供一个十进制值。 尝试以下视图：

def get_queryset(self, *args, **kwargs):
    qs = super(ProductListView, self).get_queryset(*args,**kwargs)
    query = self.request.GET.get("q", False)  # provide default value or you get a KeyError
    if query:
        filter_arg = Q(title__icontains=query) | Q(description__icontains=query)
        try:
            filter_arg |= Q(price=float(query))
        except ValueError:
            pass
        qs = self.model.objects.filter(filter_arg)
    return qs

qs = super(ProductListView, self).get_queryset(*args,**kwargs)这用于获取由视图类ProductListView的父类提供的查询集。 在此处查看python类和继承： http : //www.jesshamrick.com/2011/05/18/an-introduction-to-classes-and-inheritance-in-python/

filter_arg |= Q(price=float(query)) ，用于附加到我们的filter_arg值。 与filter_arg = filter_arg | Q(price=float(query) filter_arg = filter_arg | Q(price=float(query)

float(query)与此相关，我们试图将查询变量转换为float，并将其放入try语句中，因为它可能给我们带来ValueError在这种情况下， query值不是float 。