I have following json data in mongodb.

[
  {
    "_id": 1,
    "name": "user1",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 2,
    "name": "user2",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 3,
    "name": "user3",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 4,
    "name": "user4",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 5,
    "name": "user5",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 6,
    "name": "user6",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 7,
    "name": "user7",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  },
  {
    "_id": 8,
    "name": "user8",
    "userActivities": [
      {
        "actionTaken": "Sign in.",
        "progress": "Success."
      },
      {
        "actionTaken": "logout",
        "progress": "Success."
      }
    ]
  }
]

I am querying data for pagination as following.

[
    {
        "$match": {
            "userActivities": {
                "actionTaken": "Sign in."
            }
        }
    },
    {
        "$sort": {
            "name": -1
        }
    },
    {
        "$project": {
            "name": 1,
            "userActivities": {
                "$filter": {
                    "input": "$userActivities",
                    "as": "userActivities",
                    "cond": {
                        "$eq": [
                            "$$userActivities.actionTaken",
                            "Sign in."
                        ]
                    }
                }
            }
        }
    },
    {
        "$skip": 2
    },
    {
        "$limit": 2
    }
]

But not getting any data even though it matches filter criteria. If I remove progress field from sample data then it gives me data.

Is it something should be done differently when multiple fields are there in column to query?

CodePudding user response：

Use dot notation in your $match stage.

{
  "$match": {
    "userActivities.actionTaken": "Sign in."
  }
}

Sample Mongo Playground

CodePudding user response：

Got answer by taking help from one person. I had to use $elemMatch as following.

    [
      {
        "$match": {
          "userActivities": {
            "$elemMatch": {
              "actionTaken": "Sign in."
            }
          }
        }
      },
      {
        "$sort": {
          "name": -1
        }
      },
      {
        "$project": {
          "name": 1,
          "userActivities": {
            "$filter": {
              "input": "$userActivities",
              "as": "userActivities",
              "cond": {
                "$eq": ["$$userActivities.actionTaken", "Sign in."]
              }
            }
          }
        }
      },
      {
        "$skip": 2
      },
      {
        "$limit": 2
      }
    ]

CodePudding user response：

Maybe add the "progress" in your match stage otherways you match only objects with the single field actionTaken that do not exist in the collection :

 {
  "$match": {
    "userActivities": {
      "actionTaken": "Sign in.",
      "progress": "Success."
    }
  }
 }

Sample Mongo Playground