CODEWITHSUNDEEP
jsonmongodbmongodb-query
So4ne
So4ne

Reputation: 1182

Adding an hardcoded property to a json output

Here is my code in mongodb : .

db.mydb.aggregate([ 
    { "$group": {
        "_id": {
            "A": "$A",
            "B": "$B",
            "C": "$C"
        },

    }},
    { "$group": {
        "cpt": { '$sum': 1 } ,
        "_id": "$_id.A",
        "allowDrag": {'$literal':false},
        "expanded": {'$literal':false},
        "children": { 
            "$push": { 
                "text": "$_id.B",
                "details": "$_id.C",
                 "leaf": {'$literal': true},

            }
        },


    }}
])

I would like to add in my json output some hardcoded properties and values, it works with

"leaf": {'$literal': true}

but I don't know why I can't make it with

"allowDrag": {'$literal':false}, "expanded": {'$literal':false}

is it possible with $group?

Example of the output json I've got : 

"result" : [ 
        {
            "_id" : "A",
            "cpt" : 1,
            "children" : [ 
                {
                    "text" : "B",
                    "details" : "C",
                    "leaf" : true
                }
            ]
        }]

Example of the output json I wish I had :

"result" : [ 
        {
            "_id" : "A",
            "cpt" : 1,
            "allowDrag" : false,
            "expanded" : false,
            "children" : [ 
                {
                    "text" : "B",
                    "details" : "C",
                    "leaf" : true
                }
            ]
        }]

Upvotes: 2

Views: 230

Answers (1)

chridam
chridam

Reputation: 103365

Use the $literal operator in the $project pipeline to return the new fields set to boolean values of false:

db.mydb.aggregate([ 
    { 
        "$group": {
            "_id": {
                "A": "$A",
                "B": "$B",
                "C": "$C"
            }
        }
    },
    { 
        "$group": {
            "cpt": { '$sum': 1 } ,
            "_id": "$_id.A",        
            "children": { 
                "$push": { 
                    "text": "$_id.B",
                    "details": "$_id.C",
                    "leaf": {'$literal': true}    
                }
            }
        }    
    },
    {
         "$project": { 
             "allowDrag": {'$literal':false},
             "expanded": {'$literal':false},
             "cpt": 1,
             "children": 1 
         }       
    }
])

Tested with the following collection sample:

db.mydb.insert([
    {
        "A": "test1",
        "B": "test2",
        "C": "test3"
    },
    {
        "A": "test1",
        "B": "test2",
        "C": "test2"
    },
    {
        "A": "test2",
        "B": "test2",
        "C": "test3"
    },
    {
        "A": "test2",
        "B": "test2",
        "C": "test3"
    }
])

The above aggregation gives the following results:

/* 0 */
{
    "result" : [ 
        {
            "_id" : "test1",
            "cpt" : 2,
            "children" : [ 
                {
                    "text" : "test2",
                    "details" : "test2",
                    "leaf" : true
                }, 
                {
                    "text" : "test2",
                    "details" : "test3",
                    "leaf" : true
                }
            ],
            "allowDrag" : false,
            "expanded" : false
        }, 
        {
            "_id" : "test2",
            "cpt" : 1,
            "children" : [ 
                {
                    "text" : "test2",
                    "details" : "test3",
                    "leaf" : true
                }
            ],
            "allowDrag" : false,
            "expanded" : false
        }
    ],
    "ok" : 1
}

Upvotes: 2

Related Questions