blocks|key|1002664|text|没有“内置”的方法可以做到这一点。Django每次都会引发DoesNotExist异常。在python中处理此问题的惯用方法是将其包装在try+catch中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1002665|try:
++++go+=+SomeModel.objects.get(foo='bar')
except+SomeModel.DoesNotExist:
++++go+=+None|code-block|syntax|javascript|1002666|我所做的就是将models.Manager子类化，创建一个类似上面代码的safe_get，并将该管理器用于我的模型。这样你就可以编写：SomeModel.objects.safe_get(foo='bar')。|offset|length|style|CODE|1002667|entityMap^0|0|0|10|8|1V|11|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

There is no 'built in' way to do this. Django will raise the DoesNotExist exception every time.
The idiomatic way to handle this in python is to wrap it in a try catch:

<pre><code>try:
 go = SomeModel.objects.get(foo='bar')
except SomeModel.DoesNotExist:
 go = None
</code></pre>

What I did do, is to subclass models.Manager, create a <code>safe_get</code> like the code above and use that manager for my models. That way you can write: <code>SomeModel.objects.safe_get(foo='bar')</code>.

blocks|key|1217348|text|从Django1.6开始，你可以像这样使用first()方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1217349|Content.objects.filter(name="baby").first()|code-block|syntax|javascript|1217350|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/dev/ref/models/querysets/#first^0|L|7|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Since django 1.6 you can use <a href="https://docs.djangoproject.com/en/dev/ref/models/querysets/#first" rel="noreferrer">first()</a> method like so:

<pre><code>Content.objects.filter(name="baby").first()
</code></pre>

blocks|key|1002723|text|您可以为此创建一个泛型函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1002724|def+get_or_none(classmodel,+**kwargs):
++++try:
++++++++return+classmodel.objects.get(**kwargs)
++++except+classmodel.DoesNotExist:
++++++++return+None|code-block|syntax|javascript|1002725|如下所示：|1002726|go+=+get_or_none(Content,name="baby")|1002727|如果没有匹配的条目返回内容条目，则go将为None。|offset|length|style|CODE|1002728|注意:如果name="baby"返回多个条目，则会引发异常MultipleObjectsReturned。|1002729|您应该在数据模型上处理它，以避免此类错误，但您可能更喜欢在运行时记录它，如下所示：|1002730|def+get_or_none(classmodel,+**kwargs):
++++try:
++++++++return+classmodel.objects.get(**kwargs)
++++except+classmodel.MultipleObjectsReturned+as+e:
++++++++print('ERR====>',+e)

++++except+classmodel.DoesNotExist:
++++++++return+None|1002731|entityMap^0|0|0|0|0|H|2|L|4|0|5|B|T|N|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|12|8|@$M|13|N|14|O|P]|$M|15|N|16|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|17|8|@$M|18|N|19|O|P]|$M|1A|N|1B|O|P]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1C|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|W|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|X|$]]

You can create a generic function for this.
<pre><code>def get_or_none(classmodel, **kwargs):
 try:
 return classmodel.objects.get(**kwargs)
 except classmodel.DoesNotExist:
 return None
</code></pre>
Use this like below:
<pre><code>go = get_or_none(Content,name=&quot;baby&quot;)
</code></pre>
<code>go</code> will be <code>None</code> if no entry matches else will return the Content entry.
Note:It will raises exception <code>MultipleObjectsReturned</code> if more than one entry returned for <code>name=&quot;baby&quot;</code>.
You should handle it on the data model to avoid this kind of error but you may prefer to log it at run time like this:
<pre><code>def get_or_none(classmodel, **kwargs):
 try:
 return classmodel.objects.get(**kwargs)
 except classmodel.MultipleObjectsReturned as e:
 print('ERR====&gt;', e)

 except classmodel.DoesNotExist:
 return None
</code></pre>

blocks|key|1217615|text|你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217616|go++=+Content.objects.filter(name="baby").first()|code-block|syntax|javascript|1217617|现在，go变量可以是您想要的对象，也可以不是|1217618|参考：https://docs.djangoproject.com/en/1.8/ref/models/querysets/#django.db.models.query.QuerySet.first|offset|length|1217619|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/1.8/ref/models/querysets/#django.db.models.query.QuerySet.first^0|0|0|0|3|2P|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@]|9|@$K|Y|L|Z|1|10]]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

You can do it this way:

<pre><code>go = Content.objects.filter(name="baby").first()
</code></pre>

Now go variable could be either the object you want or None

Ref: <a href="https://docs.djangoproject.com/en/1.8/ref/models/querysets/#django.db.models.query.QuerySet.first" rel="noreferrer">https://docs.djangoproject.com/en/1.8/ref/models/querysets/#django.db.models.query.QuerySet.first</a>

blocks|key|1002833|text|为了让事情变得更简单，下面是我写的一段代码，基于这里精彩回复的输入：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1002834|class+MyManager(models.Manager):

++++def+get_or_none(self,+**kwargs):
++++++++try:
++++++++++++return+self.get(**kwargs)
++++++++except+ObjectDoesNotExist:
++++++++++++return+None|code-block|syntax|javascript|1002835|然后在你的模型中：|1002836|class+MyModel(models.Model):
++++objects+=+MyManager()|1002837|就这样。现在您有了MyModel.objects.get()和MyModel.objetcs.get_or_none()|1002838|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

To make things easier, here is a snippet of the code I wrote, based on inputs from the wonderful replies here:

<pre><code>class MyManager(models.Manager):

 def get_or_none(self, **kwargs):
 try:
 return self.get(**kwargs)
 except ObjectDoesNotExist:
 return None
</code></pre>

And then in your model:

<pre><code>class MyModel(models.Model):
 objects = MyManager()
</code></pre>

That's it.
Now you have MyModel.objects.get() as well as MyModel.objetcs.get_or_none()

blocks|key|1002919|text|您可以使用带有过滤器的exists：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1002920|Content.objects.filter(name="baby").exists()
#returns+False+or+True+depending+on+if+there+is+anything+in+the+QS|code-block|syntax|javascript|1002921|如果你只想知道它是否存在，这只是一种选择|1002922|entityMap^0|B|6|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

you could use <code>exists</code> with a filter:

<pre><code>Content.objects.filter(name="baby").exists()
#returns False or True depending on if there is anything in the QS
</code></pre>

just an alternative for if you only want to know if it exists

blocks|key|1003183|text|它是您可能不想重新实现的annoying+functions之一：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1003184|from+annoying.functions+import+get_object_or_None
#...
user+=+get_object_or_None(Content,+name="baby")|code-block|syntax|javascript|1003185|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/skorokithakis/django-annoying#get_object_or_none-function^0|C|I|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

It's one of those <a href="https://github.com/skorokithakis/django-annoying#get_object_or_none-function" rel="noreferrer">annoying functions</a> that you might not want to re-implement:

<pre><code>from annoying.functions import get_object_or_None
#...
user = get_object_or_None(Content, name="baby")
</code></pre>

blocks|key|1217150|text|在视图中的不同点处理异常实际上可能是在models.py文件中定义自定义Model+Manager的cumbersome..What，如|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217151|class+ContentManager(model.Manager):
++++def+get_nicely(self,+**kwargs):
++++++++try:
++++++++++++return+self.get(kwargs)
++++++++except(KeyError,+Content.DoesNotExist):
++++++++++++return+None|code-block|syntax|javascript|1217152|然后将其包含在content+Model类中|1217153|class+Content(model.Model):
++++...
++++objects+=+ContentManager()|1217154|这样，就可以很容易地在视图中处理它，即|1217155|post+=+Content.objects.get_nicely(pk+=+1)
if+post:
++++#+Do+something
else:
++++#+This+post+doesn't+exist|1217156|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Handling exceptions at different points in your views could really be cumbersome..What about defining a custom Model Manager, in the models.py file, like

<pre><code>class ContentManager(model.Manager):
 def get_nicely(self, **kwargs):
 try:
 return self.get(kwargs)
 except(KeyError, Content.DoesNotExist):
 return None
</code></pre>

and then including it in the content Model class

<pre><code>class Content(model.Model):
 ...
 objects = ContentManager()
</code></pre>

In this way it can be easily dealt in the views i.e.

<pre><code>post = Content.objects.get_nicely(pk = 1)
if post:
 # Do something
else:
 # This post doesn't exist
</code></pre>

blocks|key|1003413|text|也许你最好使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1003414|User.objects.filter(username=admin_username).exists()|code-block|syntax|javascript|1003415|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Maybe is better you use:

<pre class="lang-py prettyprint-override"><code>User.objects.filter(username=admin_username).exists()
</code></pre>

blocks|key|1003322|text|如果您想要一个简单的单行解决方案，并且不涉及异常处理、条件语句或Django+1.6%2B的要求，请执行以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1003323|x+=+next(iter(SomeModel.objects.filter(foo='bar')),+None)|code-block|syntax|javascript|1003324|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you want a simple one-line solution that doesn't involve exception handling, conditional statements or a requirement of Django 1.6+, do this instead:

<pre><code>x = next(iter(SomeModel.objects.filter(foo='bar')), None)
</code></pre>

blocks|key|1217489|text|从django+1.7开始，你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217490|class+MyQuerySet(models.QuerySet):

++++def+get_or_none(self,+**kwargs):
++++++++try:
++++++++++++return+self.get(**kwargs)
++++++++except+self.model.DoesNotExist:
++++++++++++return+None


class+MyBaseModel(models.Model):

++++objects+=+MyQuerySet.as_manager()


class+MyModel(MyBaseModel):
++++...

class+AnotherMyModel(MyBaseModel):
++++...|code-block|syntax|javascript|1217491|"MyQuerySet.as_manager()“的优点是以下两种方法都可以工作：|1217492|MyModel.objects.filter(...).get_or_none()
MyModel.objects.get_or_none()|1217493|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

From django 1.7 onwards you can do like:

<pre><code>class MyQuerySet(models.QuerySet):

 def get_or_none(self, **kwargs):
 try:
 return self.get(**kwargs)
 except self.model.DoesNotExist:
 return None


class MyBaseModel(models.Model):

 objects = MyQuerySet.as_manager()


class MyModel(MyBaseModel):
 ...

class AnotherMyModel(MyBaseModel):
 ...
</code></pre>

The advantage of "MyQuerySet.as_manager()" is that both of the following will work:

<pre><code>MyModel.objects.filter(...).get_or_none()
MyModel.objects.get_or_none()
</code></pre>

blocks|key|1217707|text|这是Django的get_object_or_404的一个模仿者，除了该方法返回None之外。当我们必须使用only()查询来检索某些字段时，这是非常有用的。此方法可以接受模型或查询集。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1217708|from+django.shortcuts+import+_get_queryset


def+get_object_or_none(klass,+*args,+**kwargs):
++++"""
++++Use+get()+to+return+an+object,+or+return+None+if+object
++++does+not+exist.
++++klass+may+be+a+Model,+Manager,+or+QuerySet+object.+All+other+passed
++++arguments+and+keyword+arguments+are+used+in+the+get()+query.
++++Like+with+QuerySet.get(),+MultipleObjectsReturned+is+raised+if+more+than
++++one+object+is+found.
++++"""
++++queryset+=+_get_queryset(klass)
++++if+not+hasattr(queryset,+'get'):
++++++++klass__name+=+klass.__name__+if+isinstance(klass,+type)+else+klass.__class__.__name__
++++++++raise+ValueError(
++++++++++++"First+argument+to+get_object_or_none()+must+be+a+Model,+Manager,+"
++++++++++++"or+QuerySet,+not+'%25s'."+%25+klass__name
++++++++)
++++try:
++++++++return+queryset.get(*args,+**kwargs)
++++except+queryset.model.DoesNotExist:
++++++++return+None|code-block|syntax|javascript|1217709|entityMap^0|1I|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

This is a copycat from Django's get_object_or_404 except that the method returns None. This is extremely useful when we have to use <code>only()</code> query to retreive certain fields only. This method can accept a model or a queryset.

<pre><code>from django.shortcuts import _get_queryset


def get_object_or_none(klass, *args, **kwargs):
 """
 Use get() to return an object, or return None if object
 does not exist.
 klass may be a Model, Manager, or QuerySet object. All other passed
 arguments and keyword arguments are used in the get() query.
 Like with QuerySet.get(), MultipleObjectsReturned is raised if more than
 one object is found.
 """
 queryset = _get_queryset(klass)
 if not hasattr(queryset, 'get'):
 klass__name = klass.__name__ if isinstance(klass, type) else klass.__class__.__name__
 raise ValueError(
 "First argument to get_object_or_none() must be a Model, Manager, "
 "or QuerySet, not '%s'." % klass__name
 )
 try:
 return queryset.get(*args, **kwargs)
 except queryset.model.DoesNotExist:
 return None
</code></pre>

blocks|key|1003091|text|无一例外：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1003092|if+SomeModel.objects.filter(foo='bar').exists():
++++x+=+SomeModel.objects.get(foo='bar')
else:
++++x+=+None|code-block|syntax|javascript|1003093|使用异常：|1003094|try:
+++x+=+SomeModel.objects.get(foo='bar')
except+SomeModel.DoesNotExist:
+++x+=+None|1003095|关于什么时候应该在python中使用异常，还存在一些争论。一方面，“请求宽恕比请求许可更容易”。虽然我同意这一点，但我认为例外应该保持不变，嗯，例外，“理想情况”应该在不触及任何一个的情况下运行。|1003096|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Without exception:

<pre><code>if SomeModel.objects.filter(foo='bar').exists():
 x = SomeModel.objects.get(foo='bar')
else:
 x = None
</code></pre>

Using an exception:

<pre><code>try:
 x = SomeModel.objects.get(foo='bar')
except SomeModel.DoesNotExist:
 x = None
</code></pre>

There is a bit of an argument about when one should use an exception in python. On the one hand, "it is easier to ask for forgiveness than for permission". While I agree with this, I believe that an exception should remain, well, the exception, and the "ideal case" should run without hitting one.

blocks|key|1003235|text|我们可以使用Django内置异常，它附加到名为.DoesNotExist的模型上。因此，我们不必导入ObjectDoesNotExist异常。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1003236|取而代之的是：|1003237|from+django.core.exceptions+import+ObjectDoesNotExist

try:
++++content+=+Content.objects.get(name="baby")
except+ObjectDoesNotExist:
++++content+=+None|code-block|syntax|javascript|1003238|我们可以这样做：|1003239|try:
++++content+=+Content.objects.get(name="baby")
except+Content.DoesNotExist:
++++content+=+None|1003240|entityMap^0|N|D|1E|I|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

We can use Django builtin exception which attached to the models named as <code>.DoesNotExist</code>. So, we don't have to import <code>ObjectDoesNotExist</code> exception.

Instead doing: 

<pre><code>from django.core.exceptions import ObjectDoesNotExist

try:
 content = Content.objects.get(name="baby")
except ObjectDoesNotExist:
 content = None
</code></pre>

We can do this:

<pre><code>try:
 content = Content.objects.get(name="baby")
except Content.DoesNotExist:
 content = None
</code></pre>

blocks|key|1003458|text|我也面临着同样的问题。当你想要从你的模型中获取一个元素时，每次都要编写和读取try-except是很困难的，就像@Arthur+Debert的答案一样。因此，我的解决方案是创建一个由模型继承的Getter类：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1003459|class+Getter:
++++@classmethod
++++def+try_to_get(cls,+*args,+**kwargs):
++++++++try:
++++++++++++return+cls.objects.get(**kwargs)
++++++++except+Exception+as+e:
++++++++++++return+None

class+MyActualModel(models.Model,+Getter):
++++pk_id+=+models.AutoField(primary_key=True)
++++...|code-block|syntax|javascript|1003460|这样，我就可以获得MyActualModel或None的实际元素|1003461|MyActualModel.try_to_get(pk_id=1)|1003462|entityMap^0|12|A|2O|6|0|0|9|D|N|4|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|P|$]]

I was facing with the same problem too. It's hard to write and read <code>try-except</code> for each time when you want to get an element from your model as in @Arthur Debert's answer. So, my solution is to create an <code>Getter</code> class which is inherited by the models:
<pre><code>class Getter:
 @classmethod
 def try_to_get(cls, *args, **kwargs):
 try:
 return cls.objects.get(**kwargs)
 except Exception as e:
 return None

class MyActualModel(models.Model, Getter):
 pk_id = models.AutoField(primary_key=True)
 ...
</code></pre>
In this way, I can get the actual element of <code>MyActualModel</code> or <code>None</code>:
<pre><code>MyActualModel.try_to_get(pk_id=1)
</code></pre>

blocks|key|1217835|text|我使用Django+2.2.16。这就是我解决这个问题的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217836|from+typing+import+Any

from+django.core.exceptions+import+ObjectDoesNotExist
from+django.db+import+models
from+django.db.models.base+import+ModelBase
from+django.db.models.manager+import+Manager


class+SManager(Manager):
++++def+get_if_exist(self,+*args:+Any,+**kwargs:+Any):
++++++++try:
++++++++++++return+self.get(*args,+**kwargs)
++++++++except+ObjectDoesNotExist:
++++++++++++return+None


class+SModelBase(ModelBase):
++++def+_prepare(cls):
++++++++manager+=+SManager()
++++++++manager.auto_created+=+True
++++++++cls.add_to_class("objects",+manager)

++++++++super()._prepare()

++++class+Meta:
++++++++abstract+=+True


class+SModel(models.Model,+metaclass=SModelBase):
++++managers+=+False

++++class+Meta:
++++++++abstract+=+True|code-block|syntax|javascript|1217837|在此之后，在每个模型中，您只需导入：|1217838|from+custom.models+import+SModel


class+SUser(SModel):
++++pass|1217839|在views中，你可以这样调用：|offset|length|style|CODE|1217840|SUser.objects.get_if_exist(id=1)|1217841|entityMap^0|0|0|0|0|1|5|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@$M|Z|N|10|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

I use Django 2.2.16. And this is how I solve this problem:
<pre class="lang-py prettyprint-override"><code>from typing import Any

from django.core.exceptions import ObjectDoesNotExist
from django.db import models
from django.db.models.base import ModelBase
from django.db.models.manager import Manager


class SManager(Manager):
 def get_if_exist(self, *args: Any, **kwargs: Any):
 try:
 return self.get(*args, **kwargs)
 except ObjectDoesNotExist:
 return None


class SModelBase(ModelBase):
 def _prepare(cls):
 manager = SManager()
 manager.auto_created = True
 cls.add_to_class(&quot;objects&quot;, manager)

 super()._prepare()

 class Meta:
 abstract = True


class SModel(models.Model, metaclass=SModelBase):
 managers = False

 class Meta:
 abstract = True
</code></pre>
And after that, in every models, you just need to import in:
<pre class="lang-py prettyprint-override"><code>from custom.models import SModel


class SUser(SModel):
 pass
</code></pre>
And in <code>views</code>, you can call like this:
<pre class="lang-py prettyprint-override"><code>SUser.objects.get_if_exist(id=1)
</code></pre>

blocks|key|1217873|text|来一片怎么样？它将解析到限制1。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217874|go+=+Content.objects.filter(name="baby")[0]|code-block|syntax|javascript|1217875|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

How about a slice? It will parse to a limit 1.
<pre><code>go = Content.objects.filter(name=&quot;baby&quot;)[0]
</code></pre>

When I ask the model manager to get an object, it raises <code>DoesNotExist</code> when there is no matching object.
<pre><code>go = Content.objects.get(name=&quot;baby&quot;)
</code></pre>
Instead of <code>DoesNotExist</code>, how can I have <code>go</code> be <code>None</code> instead?

How do I get the object if it exists, or None if it does not exist in Django?

Django

当我请求模型管理器获取一个对象时，当没有匹配的对象时，它会引发DoesNotExist。go = Content.objects.get(name="baby")怎样才能让go成为None而不是DoesNotExist呢？

问如果对象存在，如何获取；如果Django中不存在，如何获取？
EN

回答 17

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问如果对象存在，如何获取；如果Django中不存在，如何获取？EN

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问如果对象存在，如何获取；如果Django中不存在，如何获取？
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