How to fetch data from array in mongodb

Question

i have below mongoDB collection data. i am trying to fetch data using typesOfExicution, companyName and projectName. i have wrote the below query for finding

db.getCollection('SETTINGS').find({'companyName':'VV', 'typesOfExicution' : 'validation', 'automation.projectName' : 'hdh'})

if i don't use automation.projectName i am able to find the data. but if i use this then it is returning 0 records.

so what is the exact query to find data from an Array.

/* 1 */
{
    "_id" : ObjectId("5abce315cabca22270eead6a"),
    "typesOfExicution" : "validation",
    "modesOfExicution" : "auto",
    "automation[0][projectName]" : "Second",
    "automation[0][modules][]" : "Second module",
    "automation[0][assets][]" : "Second assets",
    "companyName" : "VV"
}

/* 2 */
{
    "_id" : ObjectId("5abce31ccabca22270eead6b"),
    "typesOfExicution" : "validation",
    "modesOfExicution" : "auto",
    "automation[0][projectName]" : "Second",
    "automation[0][modules][]" : "Second module",
    "automation[0][assets][]" : "Second assets",
    "companyName" : "VV"
}

/* 3 */
{
    "_id" : ObjectId("5abce321cabca22270eead6c"),
    "typesOfExicution" : "validation",
    "modesOfExicution" : "auto",
    "automation[0][projectName]" : "hdh",
    "automation[0][modules][]" : "ds",
    "automation[0][assets][]" : "djv",
    "companyName" : "VV"
}

To search from an Array you would do the same as it was another field. Like: "automation.projectName: "Second", "automation.modules": "Second Module". If you need multiple conditions from the same Array, use $elemMatch — Graciano
– Graciano, Commented Mar 29, 2018 at 13:17

Rahul Raj · Accepted Answer · 2018-03-29 14:28:16Z

This is not how you should store arrays in MongoDB. You should store array elements as embedded documents. As @Alexis mentioned here, there's no clarity on what exactly is your DB collection structure, so I hope this is what expected as per your given inputs:

/* 1 */
{
"_id" : ObjectId("5abce315cabca22270eead6a"),
"typesOfExicution" : "validation",
"modesOfExicution" : "auto",
"automation" : [ 
    {
        "projectName" : "Second",
        "modules" : [ 
            "Second module"
        ],
        "assets" : [ 
            "Second assets"
        ]
    }
],
"companyName" : "VV"
}

/* 2 */
{
"_id" : ObjectId("5abce31ccabca22270eead6b"),
"typesOfExicution" : "validation",
"modesOfExicution" : "auto",
"automation" : [ 
    {
        "projectName" : "Second",
        "modules" : [ 
            "Second module"
        ],
        "assets" : [ 
            "Second assets"
        ]
    }
],
"companyName" : "VV"
}

/* 3 */
{
"_id" : ObjectId("5abce321cabca22270eead6c"),
"typesOfExicution" : "validation",
"modesOfExicution" : "auto",
"automation" : [ 
    {
        "projectName" : "hdh",
        "modules" : [ 
            "ds"
        ],
        "assets" : [ 
            "djv"
        ]
    }
],
"companyName" : "VV"
}

Once you have the data as per mentioned above, use automation.projectName and you should get results like this:

Alexis Facques · Accepted Answer · 2018-03-29 13:23:20Z

1

I'm not very sure of how your stored document is structured. I believe it looks something like:

   {
      "typesOfExicution": string,
      "modesOfExicution": string,
      "automation": [{ projectName: string, modules: string, assets: string }]
      "companyName" : string
   }

If you want to perform a query over projectName, which belongs to objects composing the array automation, you need to use the $elemMatch operator:

   db.getCollection('SETTINGS').find({'companyName':'VV', 'typesOfExicution' : 'validation', 'automation' : { $elemMatch: { 'projectName': 'myProject' } }  })

answered Mar 29, 2018 at 13:23

Alexis Facques

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