Merging multiple arrays on shared keys in Javascript

Question

I want to merge multiple arrays into one big array with shared keys.

What I've tried:

var conditions = [];
if( aa != undefined )
{
    conditions.push( { "query" : { "must" : {  "aa" : "this is aa" } } } );
}

if( bb != undefined )
{
    conditions.push( { "query" : { "must" : {  "bb" : "this is bb" } } } );
}

The above code is giving:

[
    {
        "query": {
            "must": {
                "aa": "this is aa"
            }
        }
    },
    {
        "query": {
            "must": {
                "bb": "this is bb"
            }
        }
    }
]

But I need this:

[
    {
        "query": {
            "must": [
                {
                    "aa": "this is aa"
                },
                {
                    "bb": "this is bb"
                }
            ]
        }
    }
]

I am able to do it with PHP but I need to do it in native javascript or using underscore.js

Because I am converting my app from PHP to Nodejs

Mohd Shahid
– Mohd Shahid

2015-10-16 14:10:12 +00:00
Commented Oct 16, 2015 at 14:10 — Mohd Shahid
– Mohd Shahid, Commented Oct 16, 2015 at 14:10

tymeJV · Accepted Answer · 2015-10-16 14:34:44Z

1

Define the object your pushing - push everything to the inner array first - then push the object to the outer array:

var conditions = [];
var query = { query: {} };
if( aa != undefined ) {
    if (!query["query"]["must"]) {
        query["query"]["must"] = [];
    }
    //conditions.push( { "query" : { "must" : {  "aa" : "this is aa" } } } );
    query["query"]["must"].push({  "aa" : "this is aa" });
}

if( bb != undefined ) {
    if (!query["query"]["must"]) {
        query["query"]["must"] = [];
    }
    //conditions.push( { "query" : { "must" : {  "bb" : "this is bb" } } } );
    query["query"]["must"].push({  "bb" : "this is bb" });
}

conditions.push(query);

edited Oct 16, 2015 at 14:34

answered Oct 16, 2015 at 14:13

tymeJV

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4 Comments

Mohd Shahid Over a year ago

It gives error "Uncaught TypeError: Cannot read property 'must' of undefined"

tymeJV Over a year ago

@MohammadShahid -- Edited.

Danmoreng Over a year ago

this only works if he defines the conditions himself. it doesn't work if they exist already and he just wants to merge another object in

Paul Roub Over a year ago

@user2415266 See my answer for an alternative that assumes nothing about the contents of conditions

Paul Roub · Accepted Answer · 2015-10-16 14:23:26Z

For each descendant of conditions, check if it exists, create it if it doesn't.

Then, finally, push your new object:

function addCondition(conditions, key, value) {
  conditions[0] = conditions[0] || {};  
  conditions[0].query = conditions[0].query || {};
  conditions[0].query.must = conditions[0].query.must || [];
  
  var o = {};
  o[key] = value;
  
  conditions[0].query.must.push( o );
}
  
var conditions = [];
var aa = 1, bb = 1;

if (typeof(aa) !== 'undefined')
  addCondition(conditions, "aa", "this is aa" );
if (typeof(bb) !== 'undefined')
  addCondition(conditions, "bb", "this is bb" );
if (typeof(cc) !== 'undefined')
  addCondition(conditions, "cc", "this is cc" );

document.getElementById('results').innerHTML = JSON.stringify(conditions, null, 2);

<pre id="results"></pre>

Danmoreng · Accepted Answer · 2015-10-16 14:40:58Z

1

It's not quite trivial, because I see you want to make an array out of the last inner property.

Do those Objects you push into the conditions array already exist or are you defining them yourself?

You can solve your problem with a recursive function like this I believe:

EDIT: The code produces the exact result you wanted now.

var object1 = {
    query: {
        must: {
            aa: "this is aa"
        }
    }
}

var object2 = {
    query: {
        must: {
            bb: "this is bb"
        }
    }
}

var conditions = {};

function mergeObjects(object, parentObject){
    for(var prop in object){
        if(parentObject.hasOwnProperty(prop)){
            if(typeof parentObject[prop] === "object" && shareProperties(parentObject[prop], object[prop])){
                mergeObjects(object[prop], parentObject[prop])
            }else{
                parentObject[prop] = [parentObject[prop], object[prop]];
            }
        }else{
            parentObject[prop] = object[prop];
        }   
    }
}

function shareProperties(obj1, obj2){
    for(var prop in obj1){
        if(obj2.hasOwnProperty(prop)){
            return true;
        }
    }
    return false;
}

mergeObjects(object1, conditions);
mergeObjects(object2, conditions);

Output:

"{"query":{"must":[{"aa":"this is aa"},{"bb":"this is bb"}]}}"

edited Oct 16, 2015 at 14:40

answered Oct 16, 2015 at 14:13

Danmoreng

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2 Comments

Mohd Shahid Over a year ago

I need to merge multiple arrays based on the conditions

Danmoreng Over a year ago

check the code I edited in, this should solve your problem.

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