Django:如何在模板中获取命名的相关字段 [英] Django: How to get a named related field in a template

问题描述

我有一个Django应用，主要模型为Bugs.

I have a Django app where the main model is Bugs.

我有另一个名为Scrub的模型，其中有一个指向Bugs模型的FK.

I have a second Model called Scrub, that has a FK pointing to the Bugs model.

class Scrub(models.Model):
    bug_id = models.ForeignKey(Bugs,related_name='scrublines')
    user = models.ForeignKey(User)
    time = models.DateTimeField()
    field = models.CharField(max_length=50)
    value = models.CharField(max_length=255)

    def __unicode__(self):
        return str(self.bug_id)

从外壳中，我可以添加新的Scrub条目.

From the shell, I can add new Scrub entries,.

>>> B = Bugs.objects.get(bug_id=66045)
>>> U = User.objects.get(pk=2)
>>> B.scrublines.create(user=U,time=datetime.datetime.now(),field="field1",value='value1')
<Scrub: 66045>
>>> B.scrublines.create(user=U,time=datetime.datetime.now(),field="field2",value='value2')
<Scrub: 66045>
>>> B.scrublines.create(user=U,time=datetime.datetime.now(),field="field3",value='value3')
<Scrub: 66045>

我可以遍历所有字段并进行迭代

I can walk through all of the fields by getting all, and iterating

>>> lines = B.scrublines.all()
>>> for line in lines:
...   print("%s:%s" % (line.field,line.value))
... 
field1:value1
field2:value2
field3:value3

我要从模板中执行的操作是通过指定字段名称来获得特定的相关行.我可以从外壳上得到

What I want to do from the template, is get a specific related line, by specifying the field name. I can get that from the shell

>>> B.scrublines.get(field='field1').value
u'value1'

模板遍历了所有错误，并将每个字段放入不同的表格单元格中，我想将field1，field2，field3中的值直接添加到单元格中.

The template walks through all of the bugs, and places each field into a different table cell, and I want to add the value from field1, field2, field3 directly into the cells.

{% for bug in bugs %}
<tr class="bugrow" >
    <td>{{bug.bug_id}}</td>

我可以通过在模板中指定字段名称来获得相关行吗?

Can I get a related line by specifying the field name in the template?

推荐答案

在Django模板语言中，点符号可以是字典查找.例如. {{foo.bar}} 将被视为 foo ['bar'] .

In the Django template language, the dot notation can be a dictionary lookup. E.g. {{ foo.bar }} will be treated as foo['bar'].

使用Python，我们可以将其转换为各种函数调用...

Using Python we can transform this into a function call of sorts...

class MyGetter(object):

    def __getitem__(self, item):
        return "Trying to get {}".format(item)

def home(req):
    return render(req, "hello.html", {"stuff": MyGetter()})

在 hello.html 中，如果您有类似这样的内容:

And in hello.html, if you have something like this:

<p>{{ stuff.foo }}</p>

您将在页面上看到消息正在尝试获取foo".基本上，您需要做的就是修改 __ getitem __ 的主体以适合您的目的.(并且，当然，为所有内容都提供适当的名称.)

You'll see the message "Trying to get foo" appear on the page. Basically all you need to do is modify the body of __getitem__ to suit your purposes. (And, of course, come up with appropriate names for everything.)

还有其他方法可以做到这一点(即 __ getattr __ )，但是我认为使用 __ getitem __ 最清楚.

There are other ways to do this (i.e. __getattr__) but I think using __getitem__ is the most clear.

此外，如果愿意，您还可以 使用自定义模板标签/模板过滤器.这一切都取决于你.我将这样做，因为它似乎涉及最少的运动部件.

Furthermore, you could also use custom template tags/template filters if you like. It's all up to you. This is how I would do it, since it seems to involve the fewest number of moving parts.

尝试一下:

class FieldReader(object):

    def __init__(self, bug):
        self.__bug = bug

    def __getitem__(self, item):
        return self.__bug.scrublines.get(field=item).value

您可以在模板中使用

{{ field_reader.field1 }}

获取您发送给 FieldReader 构造函数的任何 Bug 的 field1 的值.

to get the value of field1 for whatever Bug you sent to the FieldReader constructor.

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