为阵列字段更新MongoDB集合toLowercase(Update MongoDB collection toLowercase for array field)

为阵列字段更新MongoDB集合toLowercase(Update MongoDB collection toLowercase for array field)

我已经看过这两个帖子了

使用$ toLower更新MongoDB集合

和

循环遍历mongoDB中的非关联数组

但那些没有帮助我。

我有一个包含这样的文档的集合：

{ "_id": "58bda97de000ae205f77c6e0", "artistName": "ABC", "trackNames": [ "1A", "1B", "1C", "1D" ], }

我想将trackNames字段的所有值更改为小写。如下所示：

{ "_id": "58bda97de000ae205f77c6e0", "artistName": "ABC", "trackNames": [ "1a", "1b", "1c", "1d" ], }

直到现在我尝试这样：

db.artist.find().forEach(function(e) { e.trackNames.forEach(function(i){ i=i.toLowerCase(); db.artist.save(e)})})

但它不起作用。 请帮忙。

I have already seen these two posts

Update MongoDB collection using $toLower

and

To loop through non associative array in mongoDB

But those didn't helped me.

I have a collection with few documents like this:

{ "_id": "58bda97de000ae205f77c6e0", "artistName": "ABC", "trackNames": [ "1A", "1B", "1C", "1D" ], }

I want to change all the values of trackNames field to lowercase.Like this:

{ "_id": "58bda97de000ae205f77c6e0", "artistName": "ABC", "trackNames": [ "1a", "1b", "1c", "1d" ], }

Till now I tried like this:

db.artist.find().forEach(function(e) { e.trackNames.forEach(function(i){ i=i.toLowerCase(); db.artist.save(e)})})

But its not working. Please help.

最满意答案

i = i.toLowerCase()实际上并不更新对象。 相反，您可以使用地图替换数组本身：

e.trackNames = e.trackNames.map(function (trackName) { return trackName.toLowerCase(); });

这将更新原始对象上的trackNames数组，然后您可以保存该数组。

i = i.toLowerCase() does not actually update the object. Instead you can replace the array itself with a map:

e.trackNames = e.trackNames.map(function (trackName) { return trackName.toLowerCase(); });

This will update the trackNames array on the original object which you can then save.