Update in forEach on mongodb shell

Question

I have got a collection aTable with 2 records:

 {
    \"title\" : \"record 1\",
    \"fields\" : [ 
        {
            \"_id\" : 1,
              


        

Answer 1

You can make changes directly in the whole object and then save it. Try the following snippet

db.aTable.find().forEach(function (itemWrapper){
    itemWrapper.fields.forEach(function(field){
        var items = field.items;
        var newItems = [];
        items.forEach(function(item){
          var t = {'item':item,'key':0}
          newItems.push(t);      
        })
        field.items = newItems;
    })
    db.aTable.save(itemWrapper)
})

What I am doing is iterating over all items and making a new array with {item : 1 , key:0} and then setting it back to items array in field object.

This is the output after update :

{
    "_id" : ObjectId("5332a192ece4ce8362c7a553"),
    "title" : "record 1",
    "fields" : [ 
        {
            "_id" : 1,
            "items" : [ 
                {
                    "item" : 1,
                    "key" : 0
                }
            ]
        }, 
        {
            "_id" : 2,
            "items" : [ 
                {
                    "item" : 2,
                    "key" : 0
                }, 
                {
                    "item" : 3,
                    "key" : 0
                }, 
                {
                    "item" : 4,
                    "key" : 0
                }
            ]
        }, 
        {
            "_id" : 3,
            "items" : [ 
                {
                    "item" : 5,
                    "key" : 0
                }
            ]
        }
    ]
}

/* 1 */
{
    "_id" : ObjectId("5332a192ece4ce8362c7a554"),
    "title" : "record 2",
    "fields" : [ 
        {
            "_id" : 4,
            "items" : [ 
                {
                    "item" : 7,
                    "key" : 0
                }, 
                {
                    "item" : 8,
                    "key" : 0
                }, 
                {
                    "item" : 9,
                    "key" : 0
                }, 
                {
                    "item" : 10,
                    "key" : 0
                }
            ]
        }, 
        {
            "_id" : 5,
            "items" : []
        }, 
        {
            "_id" : 6,
            "items" : [ 
                {
                    "item" : 11,
                    "key" : 0
                }, 
                {
                    "item" : 12,
                    "key" : 0
                }
            ]
        }
    ]
}