将字符串拆分为 MongoDB 中的子字符串或字符数组 [英] Split string into an array of substrings or characters in MongoDB

问题描述

我需要像这样转换字段:

I need to convert fields like this:

{ 
    "_id" : ObjectId("576fd6e87d33ed2f37a6d526"), 
    "phoneme" : "JH OY1 N Z" 
}

到这样的子字符串数组中

into an arrays of substrings like this

{ 
    "_id" : ObjectId("576fd6e87d33ed2f37a6d526"), 
    "phonemes" : [ "JH", "OY1", "N", "Z" ] 
}

有时会变成这样的字符数组

and sometimes into an array of characters like this

{
    "_id" : ObjectId("576fd6e87d33ed2f37a6d526"), 
    "phonemes" : ["J", "H", " ", "O", "Y", "1", " ", "N", " ", "Z"]
}

我找到了一些代码 here 将字符串转换为数组，但它对我的目的来说有点太简单了，因为只有一个数组元素要创建.

I found some code here which converts a string into an array, but it's a bit too simple for my purposes as there is only a single array element to be created.

db.members.find().snapshot().forEach( function (x) {
   x.photos = [{"uri": "/images/" + x.photos}];
   db.members.save(x);
 });

我可以在 mongo shell 语句中使用整个 javascript 语言吗?

Is the entire javascript language available to me from within mongo shell statements?

推荐答案

假设我们集合中的文档如下所示:

Suppose that the documents in our collection look like this:

{ "phoneme" : "JH OY1 N Z" }
{ "phoneme" : "foobar" }

在 3.4+ 版本中，我们可以使用 $split 运算符将字段值划分为子字符串数组.

In version 3.4+, we can use $split operator to divide the field value into an array of substrings.

要将字符串拆分为字符数组，我们需要应用 $substrCP 表达式使用 $map 运算符.

To split a string into an array of characters, we need to apply a $substrCP expression to the array of all chars in the string index using the $map operator.

要获取索引值数组是从 0 到字符串长度减一的所有整数，可以使用 $range 和 $strLenCP 运算符.

To get the array of index value is all integers from 0 to the string's length minus one which can generate using the $range and the $strLenCP operators.

我们使用 $addFields 将新字段添加到初始文档的管道阶段，但为了使其持久化，我们可以 创建视图或使用 $out 聚合管道算子.

We use the $addFields pipeline stage to add the new fields to the initial document, but for this to be persistent, we can either create a view or overwrite our collection using the $out aggregation pipeline operator.

[
    {
        "$addFields":{
            "arrayOfPhonemeChar":{
                "$map":{
                    "input":{
                        "$range":[
                            0,
                            {
                                "$strLenCP":"$phoneme"
                            }
                        ]
                    },
                    "in":{
                        "$substrCP":[
                            "$phoneme",
                            "$$this",
                            1
                        ]
                    }
                }
            },
            "phonemeSubstrArray":{
                "$split":[
                    "$phoneme",
                    " "
                ]
            }
        }
    }
]

产生如下所示的东西:

{
    "phoneme" : "JH OY1 N Z",
    "arrayOfPhonemeChar" : ["J", "H", " ", "O", "Y", "1", " ", "N", " ", "Z"],
    "phonemeSubstrArray" : ["JH", "OY1", "N", "Z"]
},
{
    "phoneme" : "foobar",
    "arrayOfPhonemeChar" : ["f", "o", "o", "b", "a", "r"],
    "phonemeSubstrArray" : ["foobar"]
}

这篇关于将字符串拆分为 MongoDB 中的子字符串或字符数组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！