在Django模板中访问带有下划线的dict元素 [英] Accessing dict elements with leading underscores in Django Templates

问题描述

我正在尝试使用以下划线字符开头的键访问dict的元素。例如：

my_dict = {_source：'xyz'}

我试图在Django模板中访问它们。显然，我意识到你不能从Django模板访问强调的python变量（因为它们在Python中被认为是私有的），但是这是一个dict对象，其中任何不可变对象是一个有效的键。

我无法使用{{my_dict._source}}访问Django模板中的上述dict，所以我假设Django正在阻止它。是准确吗？

我有点希望Django对变量开始的一些变数，它们从下划线开始，就像仍然在进行dict查找（第一件事据说是尝试），但拒绝进行属性查找，方法调用和列表索引查找，因为下划线的前缀变量将无效。我很快就失去了希望。

为了记录，我知道有人会建议只要更改dict，但这实际上是由rawes库返回的多级字典在ElasticSearch实例上执行REST API请求时。

解决方案

该文档提到您不能使变量以下划线开头：

变量名必须由任何字母（AZ），任何数字（0-9），下划线（但不能以下划线开头）或点组成。

但是你可以轻松地写一个自定义模板过滤器以模拟字典的 get 方法：

  @ register.filter（name ='get'）
 def get（d，k）：
 return d.get（k，None）
  

和

  {{my_dict | get： _my_key}} 
  

I am trying to access elements of a dict with keys that start with the underscore character. For example:

my_dict = {"_source": 'xyz'}

I'm trying to access them in a Django template. Obviously I realise that you can't access underscored python variables from a Django template (because they are considered private in Python) but this is a dict object where any immutable object is a valid key.

I can't access the above dict in a Django template using {{ my_dict._source }} so I assume Django is preventing it. Is that accurate?

I am kind of hoping Django does something sane with variables that start with underscore like still doing dict lookups (the first thing is supposedly tries) but refuses to do attribute lookups, method calls and list index lookups since an underscored prefixed variable would be invalid. I am quickly loosing hope though.

For the record, I know someone will suggest to just change the dict but this is actually a multi-levelled dictionary returned by the rawes library when executing REST API request on a ElasticSearch instance.

解决方案

The docs mention that you can't have a variable start with an underscore:

Variable names must consist of any letter (A-Z), any digit (0-9), an underscore (but they must not start with an underscore) or a dot.

but you can easily write a custom template filter to mimic the dictionary's get method:

@register.filter(name='get')
def get(d, k):
    return d.get(k, None)

and

{{ my_dict|get:"_my_key" }}

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