在Django，Python中使用MongoEngine查询嵌入式文档

Question

I need to get all EmbeddedDocuments of type Subject from Document Lesson, where Subject.subject_name = 'Something'. I am trying to do the following and it's not working for me:

results = Lesson.objects.filter(subject__match={'subject.subject_name':'Math'})

My models:

class Subject(EmbeddedDocument):
    subject_code = IntField()
    subject_name = StringField(max_length=60)
    hours = IntField(required=False)

    def __unicode__(self):
        return smart_unicode(self.subject_name)

class Lesson(Document):
    subject = EmbeddedDocumentField(Subject)
    teacher = EmbeddedDocumentField(Teacher)
    group = EmbeddedDocumentField(Group)
    room = EmbeddedDocumentField(Room)
    attendance = IntField()

    def __unicode__(self):
        return smart_unicode(self.id)

Thank you all in advance! Have a nice day! :)

Answer 1

Taking into account the following link https://mongoengine-odm.readthedocs.org/guide/querying.html it becomes obvious, that the raw function can solve the task:

It is possible to provide a raw PyMongo query as a query parameter, which will be integrated directly into the query. This is done using the raw keyword argument:

results = Lesson.objects(__raw__={'subject.subject_name': 'Math'})