JSON update array inside of object

Question

Here's what my JSON response looks like:

"_id" : 537,
    "quizzes" : [
        {
            "wk" : 1,
            "score" : [
                10
            ]
        },
        {
            "wk" : 2,
            "score" : [
                8
            ]
        },
        {
            "wk" : 3,
            "score" : [
                5
            ]
        },
        {
            "wk" : 4,
            "score" : [
                6
            ]
        }
    ]
}

I'm trying to update the score array inside one of the objects, here's my attempt at it:

db.collection('connect').update({_id: id}, {$push: { quizzes[0]: { score: 89  }  }});

What would be the expected result? If you wish to update the score array so that it still remains a single element array then consider using the update operator modifier "$set": { "quizzes.0.score.0": 89 } as mentioned in my solution below. — chridam
– chridam, Commented Jun 20, 2015 at 22:12

chridam · Accepted Answer · 2015-06-20 22:10:18Z

2

Try the following update:

db.collection("connect").update(
    {
        "_id": id            
    }, 
    {
        "$set": { 
            "quizzes.0.score.0": 89    
        }
    }
);

which uses the dot notation to access the elements of an array and to access the fields of an embedded document.

To access an element of an array by the zero-based index position, concatenate the array name with the dot (.) and zero-based index position, and enclose in quotes:

'<array>.<index>'

edited Jun 20, 2015 at 22:10

answered Jun 20, 2015 at 21:56

chridam

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Comments

Akshat Goel · Accepted Answer · 2015-06-20 21:57:13Z

1

I think you are looking for

db.collection('connect').update({_id: id}, {$set: { "quizzes.0.score":89}  })

A better way to do it is to not reply on the index of the quizzes array and use the "wk" attribute

db.collection('connect').update({_id: id,quizzes:{$elemMatch:{"wk":1}}}, {$set: { quizzes.$.score: 89  }  }})

edited Jun 20, 2015 at 21:57

answered Jun 20, 2015 at 21:53

Akshat Goel

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3 Comments

Ajax jQuery Over a year ago

The brackets are giving me a syntax error: SyntaxError: Unexpected token [

Akshat Goel Over a year ago

$ is the positional operator. Which replaces the hard coded 0 in the previous query

Ajax jQuery Over a year ago

That seems to not be working for me, can you check this question I posted? stackoverflow.com/questions/30961717/…

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