'RelatedManager' 对象是不可迭代的 Django

Question

嘿，我在 SO 上浏览了一些类似的帖子，但没有找到任何可以解决我问题的东西。我有以下型号，

from django.db import models

class Areas(models.Model):

    name =  models.CharField(max_length = 120)
    order_in_sidebar_network = models.IntegerField(blank=True, null=True)
    order_in_section_network = models.IntegerField(blank=True, null=True)


    def __unicode__ (self):
        return self.area_name

    class Meta:
        verbose_name_plural = "Areas"
        verbose_name = "Area"

class Countries(models.Model):
    name = models.CharField(max_length = 120, help_text = "The name of the country")
    area = models.ForeignKey(Areas, verbose_name = 'Area')

    def __unicode__ (self):
        return self.name

    class Meta:
        verbose_name_plural = "Countries"
        verbose_name = "Country"
        ordering = ['name']



class Offices(models.Model):
    country = models.ForeignKey(Countries, verbose_name = 'Country')
    name = models.CharField(max_length = 255, help_text = "The name of this office, IE London")
    main_office = models.BooleanField(default= False, help_text = "Is this office a key location?", verbose_name = "Key Location")
    address_1 = models.CharField(max_length = 255, null = True, blank = True)
    address_2 = models.CharField(max_length = 255, null = True, blank = True)
    address_3 = models.CharField(max_length = 255, null = True, blank = True)
    city = models.CharField(max_length = 255, null = True, blank = True)
    postcode = models.CharField(max_length = 20)
    tel = models.CharField(max_length = 30, null= True, blank = True, help_text = "Optional telephone contact number")
    mobile = models.CharField(max_length = 30, null= True, blank = True, help_text = "Optional mobile contact number")
    fax = models.CharField(max_length = 30, null= True, blank = True, help_text = "Optional fax contact number")
    data_1 = models.CharField(max_length = 255, null = True, blank = True, help_text = "Optional additional data", verbose_name = "Additional information")
    data_2 = models.CharField(max_length = 255, null = True, blank = True, help_text = "Optional additional data", verbose_name = "Additional information")

    class Meta:
        verbose_name_plural = "Offices"
        verbose_name = "Office"
        ordering = ['name']

    def __unicode__(self):
        return self.name

class OfficeMembers(models.Model):
    name = models.CharField(max_length = 60, help_text = "Please tell us this person name")
    title = models.CharField(max_length = 100, help_text = "The person's title, IE Managing Director")
    email = models.EmailField(max_length = 255, null = True, blank = True, help_text = "Optional email address for this person")
    email2 = models.EmailField(max_length = 255, null = True, blank = True, help_text = "Optional second email address for this person")
    phone = models.CharField(max_length = 30, null = True, blank  = True, help_text = "Optional contact number for this person")
    mobile = models.CharField(max_length = 30, null = True, blank  = True, help_text = "Optional mobile contact number for this person")
    office = models.ForeignKey(Offices, null = True)
    class Meta:
        verbose_name_plural = "Office Memebers"
        verbose_name = "Office memebr"
        ordering = ['name']

    def __unicode__(self):
        return self.name

我设置了以下视图

def index(request):

    cache_key = "world_areas"
    cache_time = 60

    world_areas_cache = cache.get(cache_key)

    #if no cache is set, grab the objects, and set the cache

    logger.debug(world_areas)
    if not world_areas_cache:
        logger.info('No cache found grabbing objects')
        world_areas = Areas.objects.select_related().all()
        #cache.set(cache_key, world_areas, cache_time)
        logger.debug(world_areas)
    else:
        logger.info("Getting from cache")
        world_areas = world_areas_cache

    return render_to_response('network/index.html', {'world_areas':world_areas}, context_instance=RequestContext(request))

尝试像这样迭代 world_areas 对象

{% for area in world_areas %}

产生一个模板语法错误

'RelatedManager' 对象不可迭代

有人知道为什么会这样吗？似乎真的无法解决这个问题！扼杀这在 shell 中为我工作：S 我错过了一些明显的东西吗？？？

非常感谢任何能够提供帮助的人！

Answer 1

Callall() 从管理器中检索元素。

{% for area in world_areas.all %}

Answer 2

一般来说，最好使用values 或values_list 将数据从查询集传递到模板。

world_areas = Areas.objects.select_related().all().values_list('name', 'order_in_sidebar_network', ...)

如果您以前没有使用过 values 函数，请查看 Django docs 了解如何使用它。

Answer 3

我因一个鲁莽的错误遇到了这个问题：

 for physicalserver in task.physicalservers:
        physicalserver.relieve_task()

task.physicalservers 是RelatedManager 对象，在我的情况下，我应该获取任务的物理服务器，应该添加.all()。

for physicalserver in task.physicalservers.all():

Answer 4

您必须迭代 set 以获取与模型中的 fk 相关的值。

class Area(models.Model):
    name =  models.CharField(max_length = 120)
    order_in_sidebar_network = models.IntegerField(blank=True, null=True)
    order_in_section_network = models.IntegerField(blank=True, null=True)


class CountryArea(models.Model):
    name = models.CharField(max_length = 120)
    area = models.ForeignKey(Area, verbose_name = 'Area')

 ## Assuming you have an object; area
 ## To get the all the counties related to that area you can do;
    {% for obj in area.countryarea_set.all %}
        <h4> {{ obj.name }} </h4>
    {% endfor %}