Merge an array of objects using key value in lodash? - node.js

Question

I'm using node.js and lodash.
I have data like this:
[
{
to: [ 'foo#bar.com', 'foo1#bar.com' ],
submittedSubs: [ [Object] ]
},
{
to: [ 'foo#bar.com', 'foo2#bar.com' ],
submittedSubs: [ [Object], [Object], [Object] ]
}
]
I'd like to turn it into data like this where it's "sorted" by to
[
{
to: 'foo#bar.com',
submittedSubs: [ [Object],[Object], [Object], [Object] ]
},
{
to: 'foo1#bar.com',
submittedSubs: [ [Object] ]
},
{
to: 'foo2#bar.com',
submittedSubs: [ [Object], [Object], [Object] ]
}
]
How can I do this?
I've tried this:
spam[0].to.push('foo#bar.com');
spam[0].to.push('foo1#bar.com');
spam[1].to.push('foo#bar.com');
spam[1].to.push('foo2#bar.com');
console.log('data is',spam);
var byUser=[];
_.each(spam, function(data){
_.each(data.to,function(addr){
byUser.push({to:addr,submittedSubs:data.submittedSubs});
});
});
console.log('attempt',_.merge(byUser));
But that gives me this:
[ { to: 'foo#bar.com', submittedSubs: [ [Object] ] },
{ to: 'foo1#bar.com', submittedSubs: [ [Object] ] },
{ to: 'foo#bar.com', submittedSubs: [ [Object], [Object], [Object] ] },
{ to: 'foo2#bar.com', submittedSubs: [ [Object], [Object], [Object] ] } ]

Answer 1

This'll work for you:
var unique = {};
byUser.forEach(function(user) {
unique[user.to] = unique[user.to] || [];
unique[user.to] = unique[user.to].concat(user.submittedSubs);
});
unique = Object.keys(unique).map(function (key, i) {
return {to: key, submittedSubs: unique[key]};
});
/*
[ { to: 'foo#bar.com', submittedSubs: [ [Object] ] },
{ to: 'foo1#bar.com', submittedSubs: [ [Object] ] },
{ to: 'foo2#bar.com', submittedSubs: [ [Object], [Object], [Object], [Object] ] } ]
*/
I stand by that this should be achievable using the callback feature of _.uniq but I couldn't get it to work the way you needed it to.
You should be able to use _.uniq from lodash on your final array:
_.uniq(byUser, "to");
/*
[ { to: 'foo#bar.com', submittedSubs: [ [Object] ] },
{ to: 'foo1#bar.com', submittedSubs: [ [Object] ] },
{ to: 'foo2#bar.com', submittedSubs: [ [Object], [Object], [Object] ] } ]
*/

Answer 2

I imagine there's some nice lodash facilities to shorten this up a bit, but here's a vanilla-js solution:
var data = [
{
to: [ 'foo#bar.com', 'foo1#bar.com' ],
submittedSubs: [{ id: 'sub1' }]
},
{
to: [ 'foo#bar.com', 'foo2#bar.com' ],
submittedSubs: [{ id: 'sub2' }, { id: 'sub3' }, { id: 'sub4' }]
}
];
var emailSubsMap = data.reduce(function(result, record) {
record.to.forEach(function(email) {
result[email] = (result[email] || [])
.concat(record.submittedSubs);
});
return result;
}, {});
var formatted = Object.keys(emailSubsMap).map(function(email) {
return { to: email, submittedSubs: emailSubsMap[email] };
}).sort(function(a, b) {
return a.to <= b.to ? -1 : 1;
});
console.log(JSON.stringify(formatted));
(Formatted) console output:
[
{
"to": "foo1#bar.com",
"submittedSubs": [
{ "id": "sub1" }
]
},
{
"to": "foo2#bar.com",
"submittedSubs": [
{ "id": "sub2" },
{ "id": "sub3" },
{ "id": "sub4" }
]
},
{
"to": "foo#bar.com",
"submittedSubs": [
{ "id": "sub1" },
{ "id": "sub2" },
{ "id": "sub3" },
{ "id": "sub4" }
]
}
]
Note that I mocked up what the submittedSubs objects might look like, simply for testing purposes.
JSFiddle Example
A couple notes about the sorting:
My first version wasn't sorting correctly... it's been updated. :)
The sort method you're requesting doesn't follow JavaScript's "native" string sort order. E.g., ['foo#bar.com', 'foo2#bar.com', 'foo1#bar.com'].sort() --> ['foo1#bar.com','foo2#bar.com','foo#bar.com'], so if you really want foo#bar.com to come before foo1#bar.com, you'll need to define your sort criteria in a little more detail.