基于正则表达式搜索的查找和合并对象在两个集合之间进行匹配

Question

我需要执行$ lookup聚合并根据正则表达式匹配合并对象。一个集合具有正则表达式匹配模式。因此，基于这些模式，需要在另一个集合上执行搜索。

我有两个收藏。 （1）消息和（2）正则表达式。 这是消息收集的输出。

[{_id: ObjectId(...), message: I had a dinner at McDonald}, 

{_id: ObjectId(...), message: I booked my ticket from TicketWorld},

{_id: ObjectId(...), message: I spent my weekend at Paris},

{_id: ObjectId(...), message: I went to Paris},

{_id: ObjectId(...), message: I like McDonald}]

这是正则表达式集合的输出。

[{_id: ObjectId(...), regexMatch: /mcdonald/gi, ratePoint:3}, 

{_id: ObjectId(...), regexMatch: /paris/gi, ratePoint:4},

{_id: ObjectId(...), regexMatch: /ticketwor/gi, ratePoint:2]

我尝试使用以下代码。但是无法执行正则表达式搜索，因此无法合并对象。

db.messages.aggregate([ 

   { 

      $lookup: { 

         from: "regexes", 

         localField: "message",    

         foreignField: "regexMatch",  

         as: "fromItems"

      }

   },

   {

      $replaceRoot: { newRoot: { $mergeObjects: [ { $arrayElemAt: [ "$fromItems", 0 ] }, "$$ROOT" ] } }

   }, 

   { $project: { fromItems: 0 } } 

])

预期输出如下：

[{_id: ObjectId(...), message: I had a dinner at McDonald, ratePoint: 3}, 

{_id: ObjectId(...), message: I booked my ticket from TicketWorld ,ratePoint: 2}, 

{_id: ObjectId(...), message: I spent my weekend at Paris, ratePoint: 4},

{_id: ObjectId(...), message: I went to Paris, ratePoint: 4},

{_id: ObjectId(...), message: I like McDonald, ratePoint: 3}]