knex.js migration with automatic foreign key constraints being deferrable

gistfile1.txt

  var forOwn = require('lodash/forOwn');
  
  exports.up = function (knex) {
    var builder = knex.schema;
    
    // do some schema changes using builder

    return builder.then(() => {
      return knex('pg_constraint').select('*').where('contype', '=', 'f');
    })
    .then(data => {
      var promises = [];
      // go through all foreign key constraints and make them deferrable initally deferred
      forOwn(data, item => {
        promises.push(knex('pg_class').select('relname').where('oid', '=', item.conrelid)
        .then(data => {
          var tableName = data[0].relname;
          return knex.schema.raw('ALTER TABLE ' + tableName + ' ALTER CONSTRAINT ' + item.conname + ' DEFERRABLE INITIALLY DEFERRED');
        }));
      });
      return Promise.all(promises);
    });