blocks|key|1162353|text|get_or_create返回一个元组。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1162354|customer.source,+created+=+Source.objects.get_or_create(name="Website")|code-block|syntax|javascript|1162355|entityMap^0|0|D|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|$]]

<code>get_or_create</code> returns a tuple.

<pre><code>customer.source, created = Source.objects.get_or_create(name="Website")
</code></pre>

blocks|key|1162386|text|您遇到的问题是记录在案的get_or_create功能。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1162387|当使用"defaults“以外的关键字参数时，get_or_create的返回值是一个实例。这就是为什么它会显示返回值中的括号。|1162388|您可以使用customer.source+=+Source.objects.get_or_create(name="Website")[0]来获取正确的值。|1162389|以下是文档的链接：http://docs.djangoproject.com/en/dev/ref/models/querysets/#get-or-create-kwargs|1162390|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.djangoproject.com/en/dev/ref/models/querysets/#get-or-create-kwargs^0|C|D|0|N|D|0|5|1T|0|9|27|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|L|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S]]]]

The issue you are encountering is a documented feature of <code>get_or_create</code>.

When using keyword arguments other than "defaults" the return value of <code>get_or_create</code> is an instance. That's why it is showing you the parens in the return value.

you could use <code>customer.source = Source.objects.get_or_create(name="Website")[0]</code> to get the correct value.

Here is a link for the documentation: 
<a href="http://docs.djangoproject.com/en/dev/ref/models/querysets/#get-or-create-kwargs" rel="noreferrer">http://docs.djangoproject.com/en/dev/ref/models/querysets/#get-or-create-kwargs</a>

blocks|key|1377611|text|在@Tobu回答和@mipadi评论之后，如果对创建的标志不感兴趣，我会以一种更加pythonic的方式使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1377612|customer.source,+_+=+Source.objects.get_or_create(name="Website")|code-block|syntax|javascript|1377613|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|$]]

Following @Tobu answer and @mipadi comment, in a more pythonic way, if not interested in the created flag, I would use:

<pre><code>customer.source, _ = Source.objects.get_or_create(name="Website")
</code></pre>

blocks|key|1162456|text|get_or_create方法实际上会返回一个元组。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1162457|get_or_create方法的诀窍在于它实际上返回了一个元组(object，created)。第一个元素是您试图检索的模型的一个实例，第二个元素是一个布尔标志，用于告知该实例是否已创建。True表示实例由get_or_create方法创建，False表示从数据库中检索实例|1162458|因此，您可以执行类似于获取源实例的操作|1162459|+```+++customer.source+=+Source.objects.get_or_create(name="Website")[0]|code-block|syntax|javascript|1162460|1162461|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|P|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|Q|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|H|7|R|8|@]|9|@]|A|$I|J]]|$1|L|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|M|$]]

get_or_create method would actually return a tuple.
The trick with the get_or_create method is that it actually returns a tuple of (object, created). The first element is an instance of the model you are trying to retrieve and the second is a boolean flag to tell if the instance was created or not. True means the instance was created by the get_or_create method and False means it was retrieved from the database
So you can do something like to get the source instance
<pre><code> ``` customer.source = Source.objects.get_or_create(name=&quot;Website&quot;)[0]
 ```
</code></pre>

blocks|key|1377679|text|重要警告。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1377680|在使用get_or_create、https://docs.djangoproject.com/en/4.0/ref/models/querysets/之前，您应该注意以下事项。……警告|offset|length|1377681|此方法是原子的，假设数据库强制关键字参数的唯一性(参见unique或unique_together)。如果关键字参数中使用的字段没有唯一性约束，则对此方法的并发调用可能会导致插入具有相同参数的多行。|1377682|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/4.0/ref/models/querysets/^0|0|H|1N|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@$D|R|E|S|1|T]]|A|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]]]

Important warning.
you should take care of the following before using the get_or_create , <a href="https://docs.djangoproject.com/en/4.0/ref/models/querysets/" rel="nofollow noreferrer">https://docs.djangoproject.com/en/4.0/ref/models/querysets/</a>.
....
Warning
This method is atomic assuming that the database enforces uniqueness of the keyword arguments (see unique or unique_together). If the fields used in the keyword arguments do not have a uniqueness constraint, concurrent calls to this method may result in multiple rows with the same parameters being inserted.

I'm trying to use get_or_create for some fields in my forms, but I'm getting a 500 error when I try to do so.

One of the lines looks like this:

<pre><code>customer.source = Source.objects.get_or_create(name="Website")
</code></pre>

The error I get for the above code is:

<pre><code>Cannot assign "(&lt;Source: Website&gt;, False)": "Customer.source" 
 must be a "Source" instance.
</code></pre>

Correct way to use get_or_create?

数据库

我正尝试在表单中的某些字段中使用get_or_create，但是当我尝试这样做时，我得到了一个500错误。其中一行看起来像这样：customer.source = Source.objects.get_or_create(name="Website")对于上面的代码，我得到的错误是：Cannot assign "(<S...

问正确使用get_or_create？
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问正确使用get_or_create？
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