Difference between toJSON() & { raw: true }

Both of them are ways to get a plain object from Sequelize DAO.

Main difference is that if we pass a { raw: true } option when using findOne() or findAll() we get a flattened data.

While we use Dao.toJSON() we get a nested object.

Let's see one example from Sequelize doc.

We gonna create 2 many to many tables.
And we use raw: true option to see the result.

const Foo = sequelize.define('Foo', { name: DataTypes.TEXT });
const Bar = sequelize.define('Bar', { name: DataTypes.TEXT });
Foo.belongsToMany(Bar, { through: 'Foo_Bar' });
Bar.belongsToMany(Foo, { through: 'Foo_Bar' });

await sequelize.sync();
const amy = await User.create({ name: 'Amy' });
const faveFood1 = await FavoriteFood.create({ name: 'pizza' });
const faveFood2 = await FavoriteFood.create({ name: 'Dacquoise' });
await amy.addFavoriteFood(faveFood1);
await amy.addFavoriteFood(faveFood2);
const amyFaveFood = await amy.findAll({ 
  include: FavoriteFood,
  raw: true,
});
console.log(amyFaveFood);

Basically it's nearly the direct result from raw SQL.
In query result we definitely get seperete rows.

[
  {
    "id": 1,
    "name": "Amy",
    "FavoriteFood": {
      "id": 1,
      "name": "pizza",
      "User_FavoriteFood": {
        "UserId": 1,
        "FavoriteFoodId": 1
      }
    }
  },
  {
    "id": 1,
    "name": "Amy",
    "FavoriteFood": {
      "id": 2,
      "name": "Dacquoise",
      "User_FavoriteFood": {
        "UserId": 1,
        "FavoriteFoodId": 2
      }
    }
  }
]

However with that result we have more work handling data formatting.
We can simply use toJSON() to aggregate the parts that we want.

Take this as example, I want all FavoriteFood aggregated as an array under one key of the Dao.

const Foo = sequelize.define('Foo', { name: DataTypes.TEXT });
const Bar = sequelize.define('Bar', { name: DataTypes.TEXT });
Foo.belongsToMany(Bar, { through: 'Foo_Bar' });
Bar.belongsToMany(Foo, { through: 'Foo_Bar' });

await sequelize.sync();
const amy = await User.create({ name: 'Amy' });
const faveFood1 = await FavoriteFood.create({ name: 'pizza' });
const faveFood2 = await FavoriteFood.create({ name: 'Dacquoise' });
await amy.addFavoriteFood(faveFood1);
await amy.addFavoriteFood(faveFood2);
const amyFaveFood = await amy.findAll({ 
  include: FavoriteFood,
});
console.log(amyFaveFood.toJSON());

[
  {
    "id": 1,
    "name": "amy",
    "FavoriteFood": [
      {
        "id": 1,
        "name": "pizza",
        "User_FavoriteFood": {
          "UserId": 1,
          "FavoriteFoodId": 1
        }
      },
      {
        "id": 2,
        "name": "Dacquoise",
        "User_FavoriteFood": {
          "UserId": 1,
          "FavoriteFoodId": 2
        }
      },
    ]
  }
]

easy come easy go

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Difference between toJSON() & { raw: true }

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