Feathers: converting 0/1 to booleans (and vice versa). See comment for an explanation.

app.hooks.js

// Application hooks that run for every service
const { disallow } = require('feathers-hooks-common');
const log = require('./hooks/log');
const castResultIntegersToBoolean = require('./hooks/cast-result-integers-to-boolean');
const castQueryParamBooleansToInteger = require('./hooks/cast-query-param-booleans-to-integer');
// import uncastQueryParamBooleans from ('./hooks/uncast-query-param-booleans');

module.exports = {
  before: {
    all: [
      castQueryParamBooleansToInteger(),
      log()
    ],
    find: [],
    get: [],
    create: [],
    update: [],
    patch: [],
    remove: [],
  },

  after: {
    all: [log()],
    find: [castResultIntegersToBoolean()],
    get: [castResultIntegersToBoolean()],
    create: [castResultIntegersToBoolean()],
    update: [castResultIntegersToBoolean()],
    patch: [castResultIntegersToBoolean()],
    remove: [],
  },

  error: {
    all: [log()],
    find: [],
    get: [],
    create: [],
    update: [],
    patch: [],
    remove: [],
  },
};

cast-query-param-booleans-to-integer.js

// After hook that casts query parameters to Integer if the parameter name
// starts with `is`, `has` or `can` AND is followed by a Capitalcharacter so
// that e.g. `isFavorite: true` becomes `isFavorite: 1`.
const REGEX_BOOLEAN_FIELD = /^is[A-Z]|^has[A-Z]|^can[A-Z]/;

// eslint-disable-next-line no-unused-vars
module.exports = () => {
  return async context => {
    const queryParams = context.params.query;

    // as is the case with internal use (e.g. a get() from within a hook)
    if (queryParams === undefined) {
      return context;
    }

    // as is the case with external use
    if (Object.entries(queryParams).length === 0) {
      return context;
    }

    context.params.query = castToIntegers(queryParams);

    return context;
  };
};

function castToIntegers(params) {
  const result = {};

  for (const [key, value] of Object.entries(params)) {
    if (REGEX_BOOLEAN_FIELD.test(key)) {
      result[key] = value === 'true' ? 1 : 0;
    } else {
      result[key] = value;
    }
  }

  return result;
}

cast-result-integers-to-boolean.js

// After hook that casts field values to Javascript Boolean if the field name
// starts with `is`, `has` or `can` AND is followed by a Capitalcharacter so
// that e.g. `isFavorite: 1` becomes `isFavorite: true`.
const { getItems, replaceItems } = require('feathers-hooks-common');

const REGEX_BOOLEAN_FIELD = /^is[A-Z]|^has[A-Z]|^can[A-Z]/;

// eslint-disable-next-line no-unused-vars
module.exports = () => {
  return async context => {
    const items = getItems(context);
    const isArray = Array.isArray(items);

    if (isArray) {
      const newItems = [items.map(castToBooleans)];
      replaceItems(context, newItems[0]);
    }

    if (isArray === false) {
      const newItems = castToBooleans(items);
      replaceItems(context, newItems);
    }

    return context;
  };
};

function castToBooleans(item) {
  const result = {};

  for (const [key, value] of Object.entries(item)) {
    if (REGEX_BOOLEAN_FIELD.test(key)) {
      result[key] = !!value;
    } else {
      result[key] = value;
    }
  }

  return result;
}

When using Feathersjs with Sequelize MySQL and raw: true all booleans will appear as 0/1 to your clients. These hooks will:

• convert 0/1 to true/false in the json response
• convert incoming query params true/false to 0/1

make sure to change the REGEX for your needs