combines parts of a JSON array with another JSON array

Question

I am using Amazon web services and their database dynamodb. The database returns a query in the form of json such as this:

{ Items: 
   [ { user: 'a' },
     { user: 'an' },
     { user: 'm' } ],
  Count: 3,
  ScannedCount: 3 }

I am only interest in the "user" attributes and have no use for the count and scanned count. Sometimes I do multiple requests and recieve multipel json responses inside of my application server (nodejs). I would like to combine all these response into one json. Essentially combine all the user's into one json array and send it back. So somethimes I can reive requests such as this:

{ Items: 
   [ { from_username: 'a' },
     { from_username: 'an' },
     { from_username: 'm' } ],
  Count: 3,
  ScannedCount: 3 }


{ Items: 
   [ { from_username: 'a' } ],
  Count: 1,
  ScannedCount: 1 }


{ Items: 
   [ { from_username: 'v' },
     { from_username: 'a' }],
  Count: 2,
  ScannedCount: 2 }

And would like to combine it into something like this:

   {Items:
   [ { from_username: 'a' },
     { from_username: 'an' },
     { from_username: 'm' },
     { from_username: 'a' },
     { from_username: 'v' },
     { from_username: 'a' } ]

I tried something like this:

var json = [json1, json2, json3]

But this only concats and does not remove the unwanted count fields.

@prasun please see updated question.

user2924127
– user2924127

2015-11-25 07:32:32 +00:00
Commented Nov 25, 2015 at 7:32 — user2924127
– user2924127, Commented Nov 25, 2015 at 7:32

prasun · Accepted Answer · 2015-11-25 07:41:44Z

2

Instead of copying entire json in the Array, add only Items attributes of JSON to the array

var json = [json1.Items, json2.Items, json3.Items]

If you want to retain Items key as well use:

var json = [{Items: json1.Items}, {Items: json2.Items}, {Items:json3.Items}]

If You want all Items under one array Instead you can use:

var json = {Items: []};
json.Items = json.Items.concat(json1.Items);
json.Items = json.Items.concat(json2.Items);
json.Items = json.Items.concat(json3.Items);

edited Nov 25, 2015 at 7:41

answered Nov 25, 2015 at 7:35

prasun

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2 Comments

user2924127 Over a year ago

This is very close, but it creates 3 arrays inside of 1 (eg [ [json data 1], [json data 2], [json data 3] ) . I would instead like all the keys to be inside one array without any child arrays (all data in all arrays will have the same key, 'users').

user2924127 Over a year ago

Perfect, just what I needed. Thanks!

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