mongodb - mongo 如何更新数组的每个元素 定位符只匹配第一个

Question

现有如下格式的集合

"objectiveQuestions" : [{
      "answer" : "A",
      "index" : 2,
      "isCorrect" : 1,
      "subjectId" : 5967
    }, {
      "subjectId" : 5968,
      "answer" : "A",
      "isCorrect" : 0,
      "index" : 3
    }, ...]

现在要为每个在objectiveQuestions元素添加score字段, 并给初始值2. 请问如何构造update语句呢

Answer 1

加个 multi: true

db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

http://docs.mongodb.org/manual/reference/method/db.collection.update/

Answer 2

kemas kini({},{"$setOnInsert":{'score': 2}}, True, True)