Django模板变量值对字符串文字比较失败 [英] Django template variable value to string literal comparison fails

问题描述

我在我的模板中有以下代码，它应该将 watchinstance.shift 的值（可以是DAY或NIGHT）与文字字符串DAY。比较总是失败。

  {％for watchinstance in watchinstance_list％} 
 {％if watchinstance.shift == DAY％} 
< p> shift是DAY< / p> 
 {％endif％} 
 {％endfor％} 
  

使用 ifequal 不起作用：

  {％for watchinstance in watchinstance_list％} 
 {％ifequal watchinstance.shiftDAY％} 
< p> shift is DAY< / p> 
 {％endifequal％} 
 {％endfor％} 
  

调用 {{watchinstance.shift}} 按预期工作：

  ％watchinstance_list％} 
 {{watchinstance.shift}} 
 {％endfor％} 
  

返回DAY和NIGHT。

我检查了 watchinstance.shift 是否返回任何额外的字符，而且它看起来不像...它还有什么可以在这里丢失？

解决方案

几种可能性：

1. .shift字符串有额外的空格。使用它来仔细检查：

     {％for watchinstance in watchinstance_list％} 
    X {{watchinstance.shift} } X 
    {％endfor％} 
     




2. .shift属性不是一个字符串，但是一个字符串到DAY或NIGHT的对象。在这种情况下， {{watchinstance.shift}} 中的变量替换与字符串看起来一样，但在 {％ifequal watchinstance .shiftDAY％} 将失败。

I have the following code in my template that supposed to compare the value of watchinstance.shift, which can be either "DAY" or "NIGHT", to a literal string "DAY". The comparisson always fails.

{% for watchinstance in watchinstance_list %}
    {% if watchinstance.shift == "DAY" %}
        <p>shift is DAY</p>
    {% endif %}
{% endfor %}

Using ifequal doesn't work either:

{% for watchinstance in watchinstance_list %}
    {% ifequal watchinstance.shift "DAY" %}
        <p>shift is DAY</p>
    {% endifequal %}
{% endfor %}

However, just calling {{ watchinstance.shift }} works as expected:

{% for watchinstance in watchinstance_list %}
    {{ watchinstance.shift }}
{% endfor %}

returns DAYs and NIGHTs.

I checked whether watchinstance.shift returns any extra characters, and it doesn't look like it does... What else can I be missing here?

解决方案

A couple of possibilities:

1. The .shift string has extra whitespace. Use this to double-check:

   {% for watchinstance in watchinstance_list %}
       X{{ watchinstance.shift }}X
   {% endfor %}
   

2. The .shift attribute isn't a string, but an object that stringifies to "DAY" or "NIGHT". In that case, the variable substitution in {{ watchinstance.shift }} would look the same as a string, but the comparison in {% ifequal watchinstance.shift "DAY" %} would fail.

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