How does group by works in sequelize?

I am looking for group by queries through Sequelize and cannot seem to find any documentation.

    SELECT column, count(column)  
    FROM table 
    GROUP BY column

issue: https://github.com/sequelize/sequelize/issues/348

User.findAll({
 group: ['field']
})

i use [email protected]

I think you looking for something like this:

 Table.findAll({
   attributes: ['column1', 
     sequelize.fn('count', sequelize.col('column2'))], 
   group: ["Table.column1"]
 }).success(function (result) { });

Update: Newer versions of Sequelize uses .then instead of .success.

 Table.findAll({
   attributes: ['column1', 
     sequelize.fn('count', sequelize.col('column2'))], 
   group: ["Table.column1"]
 }).then(function (result) { });

Group by with count sequelize ORM

'field' - custom user input, you can rename this string, it's your field(column) in database

'count' - reserved sequelize keyword string need for get count in sequelize

'cnt' - custom user input, you can rename this string, it's your output count

Sequelize version 3.25.0

User.findAll({
      attributes: ['field', [sequelize.fn('count', sequelize.col('field')), 'cnt']],
      group: ['field'],
})

Try this -

Table.count(
{
   attributes: ['column'], 
   group: 'column',
} 

Example: how to add an convenient alias to the grouped function column.

I did this as a separate response mostly because it wouldn't format well in a comment... otherwise I would have just added it to Sampat's answer.

function getSumsBySomeId() {
  const criteria = {
    attributes: ['some_id', [sequelize.fn('sum', sequelize.col('some_count')), 'some_count_sum']],
    group: ['some_id'],
    raw: true
  };
  return Table.getAll(criteria);
}

YIELDS:

{ some_id: 42, some_count_sum: 100 },
{ some_id: 43, some_count_sum: 150 }
...
etc.

Your code should look something like these using ES6 standard.

Table.findAll({ attributes: ['column1', sequelize.fn('count', sequelize.col('column2'))],   group: ["Table.column1"]  }).then( (result) => { })

*Try this

Table.findAll({
     group: ['column']
})

You need to use row.get('count') to get the count, row.count won't work

The API mentioned at in this answer is correct, but there were a few tricks I was missing in order to actually get the count results out.

As mentioned at: https://stackoverflow.com/questions/32649218/how-do-i-select-a-column-using-an-alias/69890944#69890944 you need to use .get() for attribute aliased columns for some reason.

And another thing: you need to use parseInt to get an integer out of PostgreSQL count: https://stackoverflow.com/questions/47843370/postgres-sequelize-raw-query-to-get-count-returns-string-value due to bigint shenanigans.

Minimal runnable example also demonstrating ORDER BY, WHERE and HAVING:

main.js

#!/usr/bin/env node
// https://cirosantilli.com/sequelize-example
const assert = require('assert')
const { DataTypes, Op } = require('sequelize')
const common = require('./common')
const sequelize = common.sequelize(__filename, process.argv[2])
;(async () => {
const UserLikesPost = sequelize.define('UserLikesPost', {
  userId: {
    type: DataTypes.INTEGER,
  },
  postId: {
    type: DataTypes.INTEGER,
  },
}, {})
await UserLikesPost.sync({force: true})
await UserLikesPost.create({userId: 1, postId: 1})
await UserLikesPost.create({userId: 1, postId: 2})
await UserLikesPost.create({userId: 1, postId: 3})
await UserLikesPost.create({userId: 2, postId: 1})
await UserLikesPost.create({userId: 2, postId: 2})
await UserLikesPost.create({userId: 3, postId: 1})
await UserLikesPost.create({userId: 4, postId: 1})
// Count likes on all posts but:
// - don't consider likes userId 4
// - only return posts that have at least 2 likes
// Order posts by those with most likes first.
const postLikeCounts = await UserLikesPost.findAll({
  attributes: [
    'postId',
    [sequelize.fn('COUNT', '*'), 'count'],
  ],
  group: ['postId'],
  where: { userId: { [Op.ne]: 4 }},
  order: [[sequelize.col('count'), 'DESC']],
  having: sequelize.where(sequelize.fn('COUNT', '*'), Op.gte, 2)
})
assert.strictEqual(postLikeCounts[0].postId, 1)
assert.strictEqual(parseInt(postLikeCounts[0].get('count'), 10), 3)
assert.strictEqual(postLikeCounts[1].postId, 2)
assert.strictEqual(parseInt(postLikeCounts[1].get('count'), 10), 2)
assert.strictEqual(postLikeCounts.length, 2)
await sequelize.close()
})()

common.js

const path = require('path');

const { Sequelize } = require('sequelize');

function sequelize(filename, dialect, opts) {
  if (dialect === undefined) {
    dialect = 'l'
  }
  if (dialect === 'l') {
    return new Sequelize(Object.assign({
      dialect: 'sqlite',
      storage: path.parse(filename).name + '.sqlite'
    }, opts));
  } else if (dialect === 'p') {
    return new Sequelize('tmp', undefined, undefined, Object.assign({
      dialect: 'postgres',
      host: '/var/run/postgresql',
    }, opts));
  } else {
    throw new Error('Unknown dialect')
  }
}
exports.sequelize = sequelize

package.json:

{
  "name": "tmp",
  "private": true,
  "version": "1.0.0",
  "dependencies": {
    "pg": "8.5.1",
    "pg-hstore": "2.3.3",
    "sequelize": "6.5.1",
    "sqlite3": "5.0.2"
  }
}

and PostgreSQL 13.4 on Ubuntu 21.10. GitHub upstream.

Generated PostgreSQL query:

SELECT
  "postId",
  COUNT('*') AS "count"
FROM
  "UserLikesPosts" AS "UserLikesPost"
WHERE
  "UserLikesPost"."userId" != 4
GROUP BY
  "postId"
HAVING
  COUNT('*') >= 2
ORDER BY
  "count" DESC;

JOIN + GROUP BY + aggregate

See: https://stackoverflow.com/questions/42470383/sequelize-query-with-count-in-inner-join/69904521#69904521

To create a query like

SELECT key, COUNT(ref) FROM MyModel GROUP BY key

You can do this as follows

  const results = await MyModel.findAll({
    attributes: ['key', [Sequelize.fn('COUNT', Sequelize.col('ref')), 'count']],
    group: ['key']
  });

Optionally you can cast the result to something like (MyModel & { count: number })[]

Finally, to extract the count for each row, you'll need to use the getDataValue function. e.g.

results.map(r => r.getDataValue('count'))