How to map an array of nested arrays grouped by desired object values

Question

I have an array of messages which are like the following:

[
  { message: 'This is message', to: 4, from: 1},
  { message: 'This is response message', to: 1, from: 4 },
  { message: 'This is ANOTHER message with different sender', to: 1, from: 2 },
  { message: 'This is RESPONSE message to different sender', to: 2, from: 1 },
]

I have all the messages, but they are not grouped by the user-to-user conversation. What I want is to group the messages (inside an array) by to and from.

How can I achieve the following outcome:

[
  [
    { message: 'This is message', to: 4, from: 1},
    { message: 'This is response message', to: 1, from: 4 },
  ],
  [
    { message: 'This is ANOTHER message with different sender', to: 1, from: 2 },
    { message: 'This is RESPONSE message to different sender', to: 2, from: 1 }
  ],
]

In short:

Current structure is

// Individually structured messages
[message, message, message, message]

Desired outcome:

// Grouped by user-to-user conversation
// [[Conversation1], [Conversation2]]
[[message, message], [message,message]]

I have tried using lodash with return this._.values(this._.groupBy(this.messages, 'to')), but since I need to group them by two criteria, I didn't manage to come up with the logic.

Does this answer your question? How to group an array of objects based on multiple keys in Javascript? — pilchard
– pilchard, Commented Jan 27, 2022 at 12:31

Nitheesh · Accepted Answer · 2022-01-27 12:57:31Z

2

Javascript implementation with Array.reduce and Array.find

const messages = [
  { message: 'This is message', to: 4, from: 1},
  { message: 'This is response message', to: 1, from: 4 },
  { message: 'This is ANOTHER message with different sender', to: 1, from: 2 },
  { message: 'This is RESPONSE message to different sender', to: 2, from: 1 },
];
const groupedMessage = messages.reduce((acc, curr) => {
  const node = acc.find(item => item.find((msg) => (msg.from === curr.to && msg.to === curr.from) || (msg.from === curr.from && msg.to === curr.to)));
  node ? node.push(curr) : acc.push([curr]);
  return acc;
}, []);
console.log(groupedMessage);

edited Jan 27, 2022 at 12:57

answered Jan 27, 2022 at 12:27

Nitheesh

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3 Comments

Berin Aptula Over a year ago

This works! Only thing is that I forgot to give an example that there is a case where the conversation is only 1 sided. For example: Hey Good morning! (to : 4, from 2) Are you there? (to : 4, from 2) Please answer? (to : 4, from 2)

Nitheesh Over a year ago

@BerinAptula Updated the answert, please check.

Berin Aptula Over a year ago

This solved my challenge. Thanks!

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