小编Ayi*_*jla的帖子

当我在集合中使用 $lookup 时，我得到以下错误的输出

这是输出：

{"_pipeline":[{"$project":{"fulldetails":{"$concat":["$associate_name"," ","$associate_no"]},"outlets":"$outl"}},{"$lookup":{"from":"outlets","localField":"_id","foreignField":"associate_id","as":"outl"}}],"options":{}}

这是查询

  var data=Associate.aggregate([{
        $project: {
          "fulldetails": {
            $concat: ["$associate_name", " ", "$associate_no"]
          },
          "outlets": "$outl"
        }
      }, {
        $lookup: {
          from: "outlets",
          localField: "_id",
          foreignField: "associate_id",
          as: "outl"
        }
      }])

提前致谢