在MongoDB中按索引将子文档中的字段向上插入数组中 [英] upsert a field in a subdocument in an array by index in MongoDB

问题描述

我具有以下MongoDB结构

I have the following MongoDB structure

{
  _id : ...,
  other_stuff ... ,
  my_array : [
    { title: ...., body: ...., email: .... },
    { title: ...., body: ...., email: .... },
    { title: ...., body: ...., email: .... }
  ]
}

我需要在"my_array"字段中的子文档中更新/或插入(如果不存在)名为"click_number"的字段.如果"click_number"字段不存在，请插入该字段并将其设置为1；否则，将其设置为1.如果存在，将其增加1.

I need to update/or insert (if not existent) a field called "click_number" in the subdocument within the "my_array" field. If the "click_number" field is not existent, insert the field and set it to 1; if existent, increment it by 1.

首先，我不知道如何通过其索引更新数组元素，其次，我不知道如何根据字段的存在进行更新或插入.感谢您的帮助

First of all, I don't know how to update an array element by its index, and secondly, I do not know how to do update or insert depending on the existence of the field. I appreciate your help

推荐答案

您要在集合上使用update命令，如下所示(示例):

You want to use the update command on your collection as follows (example):

db.collection.update(
    { "my_array.title" : "title_one" },
    { $inc : { "my_array.$.click_number" : 1 } }
);

发生了什么事?

在update的第一个参数上，定义一个query以匹配要更新的文档.我们在名为my_array的数组中搜索名为title的属性.您当然可以通过将点表示法修改为"my_array.email"来匹配body或email.

On the first parameter of update you define a query to match documents you wish to update. We search for a property named title inside the array called my_array. You could match against body or email of course by modifying the dot notation to: "my_array.email".

第二个参数定义更新，即要应用的修改.我们有一个$inc运算符来递增字段，我们在此语句中使用了该字段. query选择具有匹配数组元素的文档.您可以使用$表示法来获取此匹配的数组项. "my_array.$"选择匹配的数组元素，该元素具有title，email和body.如果您尝试给不存在的字段赋值，MongoDB会为您做到这一点.如果该字段不存在，则$inc将该字段设置为指定的数量. $inc运算符接受正数和负数的增量.

The second parameter defines the update, the modification to apply. We have a $inc operator to increment fields, which we use in this statement. The query selects a document with the matched array element. You can reach for this matched array item with the $ notation. The "my_array.$" selects the matched array element, which has a title, email and body. If you try to give value to a non existing field, MongoDB will do it for you. If the field does not exist, $inc sets the field to the specified amount. The $inc operator accepts positive and negative incremental amounts.

了解有关更新命令的更多信息.

另一个例子:

db.collection.update(
    { _id : "john", "my_array.email" : "email" },
    { $inc : { "my_array.$.click_number" : 1 } }
);

这篇关于在MongoDB中按索引将子文档中的字段向上插入数组中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！