Update in forEach on mongodb shell

Question

I have got a collection aTable with 2 records:

 {     "title" : "record 1",     "fields" : [          {             "_id" : 1,             "items" : [                  1             ]         },         {             "_id" : 2,             "items" : [                  2,3,4             ]         },         {             "_id" : 3,             "items" : [                  5             ]         }     ] },  {         "title" : "record 2",         "fields" : [              {                 "_id" : 4,                 "items" : [                      7,8,9,10                 ]             },             {                 "_id" : 5,                 "items" : [                   ]             },             {                 "_id" : 6,                 "items" : [                      11,12                 ]             }         ]     } 

I want to update fields aTable.fields.items from

items : [ 11,12 ] 

to

items : [     {item: 11, key: 0},    {item:12, key: 0} ] 

I browse fields with forEach but I can't save it:

var t = db.aTable.find();  t.forEach(function( aRow ) {     aRow.fields.forEach( function( aField ){         aField.items.forEach( function( item ){             var aNewItem = { item: parseInt(item), ref: 0 };             db.aTable.update(item, {$set:aNewItem})         } )     } ) }); 

Answer 1

To get what you want you will need a few things:

t.forEach(function( aRow ) {     var newFields = [];     aRow.fields.forEach( function( aField ){         var newItems = [];         aField.items.forEach( function( item ){             var aNewItem = { item: parseInt(item), ref: 0 };             newItems.push( aNewItem );         } );         newFields.push({ _id: aField._id, items: newItems });     } )     aTable.update(         { _id: aRow._id },          { "$set": { "fields": newFields } }     ); }); 

So basically you need to "re-construct" your arrays before updating

Answer 2

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                 }             ]         }     ] }