如何在pymongo(python mongodb)中执行get_or_create？

Question

首先,查找是否存在文档匹配查询.

如果是,请使用新数据更新该文档.

否则,将新文档插入数据库.

Answer 1

您可以使用等于true的"upsert".然后使用"upsert"作为true运行的更新查询将完全按照您的要求执行.

• 如果存在则更新.
• 如果不存在则插入new.

来自MongoDb文档:

db.collection.update( criteria, objNew, upsert, multi )

Arguments:

    criteria - query which selects the record to update;
    objNew - updated object or $ operators (e.g., $inc) which manipulate the object
    upsert - if this should be an "upsert"; that is, if the record does not exist, insert it
    multi - if all documents matching criteria should be updated

http://www.mongodb.org/display/DOCS/Updating

例:

db.test.update({"x": "42"}, {"$set": {"a": "21"}},True)    
#True => Upsert is True

请在此处查看"更新"文档:

http://api.mongodb.org/python/current/api/pymongo/collection.html