How to add if is a leaf node in my nested hierarchies element ?

[NicoSan20]

Hi everyone ! Currently I'm using a nested hierarchies like below :

const result = await models.Category.findAll({
    where: {
      parent: null
    },
    include: [{
      model: models.Category,
      as: 'children'
    }]
  });
res.send(result);

Now, I would like to have on each element found if is an leaf node or not (leaf : true (or false)).

How can I do to get this result ? Any help will be appreciated. Thank you in advance.

[ephys]

The following has not been tested

This should return all categories that do not have children (leaves):

const result = await models.Category.findAll({
  where: {
    '$children.id$': null,
  },
  include: [{
    model: models.Category,
    as: 'children',
  }],
});

This should return all categories that do have children (not leaves):

const result = await models.Category.findAll({
  include: [{
    model: models.Category,
    as: 'children',
    required: true,
  }],
});