显示标题里面只有一次Django的if语句

Question

我在Django视图中的汽车对象如下：

'damages': [ 
     { 
      "location": "Voorbumper", 
      "type": "Kras(10 cm, leger)", 
      "severity": "Light damage", 
      'comment': "This is some comment.", 
      "images": [ 
       'http://pathtophoto.jpg', 
       'http://pathtophoto.jpg' 
      ] 
     }, 
     { 
      "location": "Vleugel rechts voor", 
      "type": "Deuk (Licht)", 
      "severity": "", 
      'comment': "", 
      "images": [ 
       'http://pathtophoto.jpg', 
       'http://pathtophoto.jpg', 
       'http://pathtophoto.jpg' 
      ] 
     }, 
     { 
      "location": "Deur links voor", 
      "type": "Kras (5 cm, leger)", 
      "severity": "", 
      'comment': "", 
      "images": [ 
       'http://pathtophoto.jpg' 
      ] 
     }, 
     { 
      "location": "Waterlijst", 
      "type": "Beschadigd", 
      "severity": "", 
      'comment': "", 
      "images": [] 
     }, 
     { 
      "location": "Antenne", 
      "type": "Ontbreekt", 
      "severity": "", 
      'comment': "", 
      "images": [ 
       'http://pathtophoto.jpg' 
      ] 
     }, 
     { 
      "location": "Antenne", 
      "type": "Ontbreekt", 
      "severity": "", 
      'comment': "", 
      "images": [] 
     } 
] 

我想通过对象循环和显示损害的图像。但我首先要用图像来显示损害，以及没有适当标题的图像损坏。

在Django模板我尝试d，如下所示：

{% for damage in car.damages %} 

    {% if damage.images|length > 0 %} 

     <div class="width-100 pad text-left primary-bg">{% trans "Shades met foto's" %}</div> 

     <div class="width-100 mar-top clear-float"> 
      <div class="width-30 bord-my-way pad-half damage-info"> 
       <div class="mar-btm-half"><b>{{ damage.location }}</b></div> 
       <div class="mar-btm-half">{{ damage.type }}</div> 
       <div class="mar-btm-half">{{ damage.severity }}</div> 
       <div class="mar-btm-half">{{ damage.comment }}</div> 
      </div> 
      <div class="width-70 pad-lft damage-photos"> 
       {% for image in damage.images|slice:"3" %} 
        <div class="width-33 pad-rgh"> 
         <img src="{{ image }}" class="width-100"/> 
        </div> 
       {% endfor %} 
      </div> 
      <div class="clear-float"></div> 
      {% if forloop.counter == 7 or forloop.counter == 14 or forloop.counter == 21 %} 
       <p style="page-break-before: always"></p> {% endif %} 

     </div> 
    {% endif %} 
{% endfor %} 

{% for damage in car.damages %} 

    {% if damage.images|length == 0 %} 
     <div class="width-100 pad text-left primary-bg mar-top">{% trans "Shades zonder foto's" %}</div> 
     <div class="green-bg">{{ damage.location }}</div> 
    {% endif %} 
{% endfor %} 

因此，我通过损害第一回路，其中damage.images|length > 0，然后在第二对我检查是否存在与damage.images|length == 0没有图像。但标题显示为每个for loop迭代。

我可以放置标题的for loop。喜欢的东西：

<div> Damages with photos </div> 
{% for damage in car.damages %} 
    {% if damage.images|length > 0 %} 
     // Show it 
    {% endif %} 
{% endfor % 

而且

<div> Damages without photos </div> 
{% for damage in car.damages %} 
    {% if damage.images|length == 0 %} 
     // Show it 
    {% endif %} 
{% endfor % 

但有时候我只有用图片或不仅损害赔偿没有图像，然后我看到标题，虽然我没有任何损害显现。

有什么办法给if statement里面做一些事情只有一次，是这样的：

{% for damage in car.damages %} 
     {% if damage.images|length > 0 %} 
      <div>Damages with the photos</div> // Show it only once when it comes here 
      // Show the damages with photos 
     {% endif %} 
{% endfor %} 

{% for damage in car.damages %} 
     {% if damage.images|length == 0 %} 
      <div>Damages without the photos</div> // Show it only once when it comes here 
      // Show the damages without photos 
     {% endif %} 
{% endfor %} 

任何想法如何解决呢？

Answer 1

我对Django和Python不再过分熟悉，但我想你可以做一个初步检查，看看有无图像损坏。

damages_with_images = [d for d in damages if d.images.length > 0] 
damages_without_images = [d for d in damages if d.images.length == 0] 

然后刚刚超过这两个单独的数组循环，只打印标题，如果他们不空...

{% if damages_with_images|length > 0 %} 
    put heading1 
{% endif %} 
# ... loop ... 

{% if damages_without_images|length > 0 %} 
    put heading2 
{% endif %} 
# ... loop ... 

当然，这是因为有多个循环的糟糕表现。

Answer 2

我会做你的位置是

1. 无论是在模板中通过两个独立的QuerySet S，第一个将包括图像和其他损害赔偿没有图像。

2. 保持QuerySet原样并创建两个自定义模板过滤器，它们可以完成与上述步骤＃1相同的工作。

案例1：

# views.py 

def my_view(request): 
    damages_w_img = Damage.objects.filter(images__isnull=False) 
    damages_wo_img = Damage.objects.filter(images__isnull=True) 
    return render(request, 'template.html', locals()) 


<!-- template.html --> 

{% if damages_w_img.exists %} 
    <h1>This list of damages contains images</h1> 
    {% for damage in damages_w_img %} 
     do stuff here, each damage has an image 
    {% endfor %} 
{% endif %} 

{% if damages_wo_img.exists %} 
    <h1>This list of damages does not contain images</h1> 
    {% for damage in damages_wo_img %} 
     do stuff here, each damage does not has an image 
    {% endfor %} 
{% endif %} 

案例2：

# custom_template_filter.py 

from django import template 

register = template.Library() 

@register.filter 
def with_images(damages): 
    return damages.objects.filter(images__isnull=False) 

@register.filter 
def without_images(damages): 
    return damages.objects.filter(images__isnull=True) 


<!-- template.html --> 

{% with damage_w_img=car.damages|with_images damage_wo_img=car.damages|without_images %} 

    {% if damages_w_img.exists %} 
     <h1>This list of damages contains images</h1> 
     {% for damage in damages_w_img %} 
      do stuff here, each damage has an image 
     {% endfor %} 
    {% endif %} 

    {% if damages_wo_img.exists %} 
     <h1>This list of damages does not contain images</h1> 
     {% for damage in damages_wo_img %} 
      do stuff here, each damage does not has an image 
     {% endfor %} 
    {% endif %} 

{% endwith %}