如何删除字符串Mongodb的子集短语

Question

我需要一些帮助来创建monogdb查询，从包含短语'?=view‘的特定URL中删除结尾。例如，三个URL是：

https://stackoverflow.com/questions/ask
https://stackoverflow.com/questions/ask100?=view
https://stackoverflow.com/questions/ask101

输出将为：

https://stackoverflow.com/questions/ask
https://stackoverflow.com/questions/ask100
https://stackoverflow.com/questions/ask101

采集示例：

Product{
id: ...
URL: 'https://stackoverflow.com/questions/ask'}

提前感谢

Answer 1

下面的aggregation with update查询从每个字符串的末尾去掉"?=view“。正则表达式/.+\?=view$/查找以子字符串"?=view“结尾的字符串。

db.test.aggregate( [
  {
       $match: { url: { $regex: /.+\?=view$/ } }
  },
  { 
      $addFields: { 
          url: { $split: [ "$url", "?" ] } 
      } 
  }
] ).forEach( doc => db.test.updateOne( { _id: doc._id }, { $set: { url: doc.url[0] } } )

Answer 2

另一种解决方案是在$split之后使用$arrayElemAt来获取不带查询字符串的URL。

db.Product.aggregate([
  {
    $project: {
      id: 1,
      URL: {
        $arrayElemAt: [
          {
            "$split": [
              "$URL",
              "?"
            ]
          },
          0
        ]
      }
    }
  }
])

MongoPlayground

Answer 3

您可以简单地使用正则表达式"/?=view"聚合以查找所有匹配的记录，然后循环逐个更新它，如下所示：

> db.product.find()
{ "_id" : ObjectId("5e0c86a4a2e621133ea3b041"), "url" : "https://stackoverflow.com/questions/ask" }
{ "_id" : ObjectId("5e0c86b1a2e621133ea3b042"), "url" : "https://stackoverflow.com/questions/ask100?=view" }
{ "_id" : ObjectId("5e0c86c1a2e621133ea3b043"), "url" : "https://stackoverflow.com/questions/ask101" }
> 
> 
> db.product.aggregate( [   
{   $match: {            url: { $regex: "/?=view" } } }, 
{ $addFields: { url: { $split: [ "$url", "?" ] } } }
]).forEach(function(matchedDoc) {printjson(matchedDoc); 
    db.product.updateOne({_id: matchedDoc._id}, {$set: {url: matchedDoc.url[0]}  } )} 
)
{
    "_id" : ObjectId("5e0c86b1a2e621133ea3b042"),
    "url" : [
        "https://stackoverflow.com/questions/ask100",
        "=view"
    ]
}
> db.product.find()
{ "_id" : ObjectId("5e0c86a4a2e621133ea3b041"), "url" : "https://stackoverflow.com/questions/ask" }
{ "_id" : ObjectId("5e0c86b1a2e621133ea3b042"), "url" : "https://stackoverflow.com/questions/ask100" }
{ "_id" : ObjectId("5e0c86c1a2e621133ea3b043"), "url" : "https://stackoverflow.com/questions/ask101" }
>