在mongoengin中向ReferenceField列表添加项

Question

我有以下蒙哥收藏的结构。在

class SkillCluster(DynamicDocument):
    Name = StringField(required=True, unique=True)
    SubClusters = ListField(StringField())
    ModifiedDate = DateTimeField(default=datetime.utcnow)
    meta = {
        'indexes': ['ClusterName'],
        'index_background': True,
        'collection': 'SkillClusters',
        'db_alias': db_alias_name
    }


class Skill(DynamicDocument):
    Name = StringField(required=True, unique=True)
    Clusters = ListField(ReferenceField(SkillCluster))
    ModifiedDate = DateTimeField(default=datetime.utcnow)
    meta = {
        'indexes': ['SkillName'],
        'index_background': True,
        'collection': 'Skill',
        'db_alias': db_alias_name
    }

SkillCluster集合的示例文档

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技能可能属于不同的集群，因为我在Skill集合中有一个Clusters列表字段。我想出了以下代码来添加一个技能

def add_skills(skill_name, cluster_string):
    cluster_sub_clusters = cluster_string.split(':', 1)
    cluster_name, sub_cluster_name = cluster_sub_clusters[0], cluster_sub_clusters[-1].strip()
    # query to test if the "SkillCluster" collection has a document that has both the cluster_name in "Name" fields & sub_cluster_name in "SubClusters" array 
    result_set = SkillCluster.objects(Name=cluster_name, SubClusters__contains=sub_cluster_name)
    if result_set:
        data_dict = {
            "ModifiedDate": datetime.utcnow(),
            "Clusters": {
                "$addToSet": result_set[0]
            }

        }
        skill = Skill.objects(Name=skill_name).modify(upsert=True, new=True, **data_dict)
    else:
        # check if document exists with name = cluster_name, if so then add sub_cluster_name to the "SubClusters" array
        result_set = SkillCluster.objects(Name=cluster_name)
        if result_set:
            result_set[0].update(add_to_set__SubClusters=sub_cluster_name)
            # ........... rest of the logic

但是我得到了一个错误-

File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/queryset/transform.py", line 277, in update
    value = field.prepare_query_value(op, value)
  File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/fields.py", line 708, in prepare_query_value
    return [self.field.prepare_query_value(op, v) for v in value]
  File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/fields.py", line 708, in <listcomp>
    return [self.field.prepare_query_value(op, v) for v in value]
  File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/fields.py", line 997, in prepare_query_value
    super(ReferenceField, self).prepare_query_value(op, value)
  File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/base/fields.py", line 174, in prepare_query_value
    self.validate(value)
  File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/fields.py", line 1003, in validate
    self.error('A ReferenceField only accepts DBRef or documents')
  File "/home/dimension/.virtualenvs/docparser/lib/python3.5/site-packages/mongoengine/base/fields.py", line 149, in error
    raise ValidationError(message, errors=errors, field_name=field_name)
mongoengine.errors.ValidationError: A ReferenceField only accepts DBRef or documents

我应该如何向ListField添加引用对象。在

谢谢。在

Answer 1

modify函数的语法导致了该问题。在

MongoEngine为update()和modify()函数使用Django风格的update关键字参数。所以也许你应该试试这样的方法：

data_dict = { 
    #"ModifiedDate": datetime.utcnow(),
    add_to_set__Clusters : result_set[0] # <= Django-style update/modify keyword arguments
} 
skill = Skill.objects(Name=skill_name).modify(upsert=True, new=True, **data_dict)

以下是指向mongoengineapi引用的链接：http://docs.mongoengine.org/apireference.html搜索update()和{}，还可以参考atomic updates部分以获取可能的更新关键字列表：http://docs.mongoengine.org/guide/querying.html#atomic-updates