Standart Flow For Better Control Of Subdocument Filtering

mongodb-unwind-match-group-workflow.js

// MongoDB Playground
// To disable this template go to Settings | MongoDB | Use Default Template For Playground.
// Make sure you are connected to enable completions and to be able to run a playground.
// Use Ctrl+Space inside a snippet or a string literal to trigger completions.

// Select the database to use.
use('mongodbVSCodePlaygroundDB');

// The drop() command destroys all data from a collection.
// Make sure you run it against proper database and collection.
db.rights.drop();

// Insert a few documents into the sales collection.
db.rights.insertMany([
  {
    chat: 1,
    messages: [
      { text: 'system', rights: ['A'] },
      { text: 'system', rights: ['B'] },
    ],
  },
  {
    chat: 2,
    messages: [
      { text: 'system', rights: ['A', 'B'] },
      { text: 'system', rights: ['A', 'C'] },
    ],
  },
  {
    chat: 3,
    messages: [
      { text: 'system', rights: ['A', 'B', 'C'] },
      { text: 'system', rights: [] },
    ],
  },
  { chat: 4, messages: [{ text: 'system', rights: [] }] },
  { chat: 5, messages: [{ text: 'system' }] },
]);

db.rights.aggregate([
  {
    $unwind: {
      path: '$messages',
      preserveNullAndEmptyArrays: true,
    },
  },
  {
    $match: {
      'messages.rights': {
        $in: ['B'],
      },
    },
  },
  {
    $group: {
      _id: '$_id',
      root: {
        $mergeObjects: '$$ROOT',
      },
      messages: {
        $push: '$messages',
      },
    },
  },
  {
    $replaceRoot: {
      newRoot: {
        $mergeObjects: ['$root', '$$ROOT'],
      },
    },
  },
  {
    $unset: ['root'],
  },
]);