MongoError: Expression $in takes exactly 2 arguments. 1 were passed in

问题

• below is my query: while executing below query getting mongoerror : Expression $in takes exactly 2 arguments. 1 were passed in. i am using $in Comparison operator

  {
      "$expr": {
          "$not": {
              "$eq":{
                  "$and": [
                      {
                          "PrName": {
                              "$in": [
                                  "pname"
                              ]
                          }
                      },
                      {
                          "AccountId": {
                              "$in": [
                                  "34562",                      
                                  "88765",
                                  "87654",
                                  "12345"
                              ]
                          }
                      }
                  ]
              }
          }
      }
  }
  

回答1:

When you use $expr, the operator expressions syntax changes a little:

{ $in: [ <expression>, <array expression> ] }

---

{
  "$expr": {
    "$not": {
      "$and": [
        {
          "$in": [
            "$PrName",
            [
              "pname"
            ]
          ]
        },
        {
          "$in": [
            "$AccountId",
            [
              "34562",
              "88765",
              "87654",
              "12345"
            ]
          ]
        }
      ]
    }
  }
}

来源：https://stackoverflow.com/questions/62407638/mongoerror-expression-in-takes-exactly-2-arguments-1-were-passed-in