是否可以在 $regex 中使用 MongoDB 表格字段值作为模式?
是的,你可以使用 $indexOfCP 来将字段值用作模式。我们来创建一个带有文档的集合 −
> db.demo88.insertOne( ... { ... "Name": "Chris", ... "PassoutYear": "2020", ... "websiteName": "chris.shop.com/Carol-2020-" ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e2c14c471bf0181ecc422b1") } > db.demo88.insertOne( ... { ... "Name": "David", ... "PassoutYear": "2010", ... "websiteName": "david.bigshop.com/David-2010-" ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e2c14c571bf0181ecc422b2") }
使用 find() 方法显示集合中的所有文档 −
> db.demo88.find();
这将生成以下输出 −
{ "_id" : ObjectId("5e2c14c471bf0181ecc422b1"), "Name" : "Chris", "PassoutYear" : "2020", "websiteName" : "chris.shop.com/Carol-2020-" } { "_id" : ObjectId("5e2c14c571bf0181ecc422b2"), "Name" : "David", "PassoutYear" : "2010", "websiteName" : "david.bigshop.com/David-2010-" }
以下是在 $regex 中使用字段值作为模式的查询 −
> db.demo88.aggregate([ { "$match": { "$expr": { "$ne": [ { "$indexOfCP": ["$websiteName", "$Name"] }, -1 ] } }} ])
这将生成以下输出 −
{ "_id" : ObjectId("5e2c14c571bf0181ecc422b2"), "Name" : "David", "PassoutYear" : "2010", "websiteName" : "david.bigshop.com/David-2010-" }
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