擅长:python、mysql、java
<p>发件人:<a href="http://docs.mongoengine.org/guide/defining-documents.html#uniqueness-constraints" rel="nofollow noreferrer">http://docs.mongoengine.org/guide/defining-documents.html#uniqueness-constraints</a></p>
<blockquote>
<p>You may also specify multi-field uniqueness constraints by using
<code>unique_with</code>, which may be either a single field name, or a list or
tuple of field names</p>
</blockquote>
<p>在您的情况下:</p>
<pre><code>class SocialGroup(Document):
timestamp = DateTimeField(default=datetime.now)
course_name = StringField()
group_name = StringField(choices=[('A', 1), ('B', 1), ('C', 1),('D', 1), ('E', 1), ('F', 1), ('None',1)], default="None",
unique_with='course_name')
</code></pre>
<p>或者更复杂:</p>
^{pr2}$