如何用Knex修改postgres sql约束？

npm install knex pg

module.exports = {
  development: {
    client: 'pg',
    connection: {
      host: 'your_host',
      port: 'your_port',
      user: 'your_username',
      password: 'your_password',
      database: 'your_database'
    },
    migrations: {
      tableName: 'knex_migrations'
    }
  }
};

knex migrate:make modify_constraints

exports.up = function(knex) {
  return knex.schema.alterTable('your_table_name', function(table) {
    table.dropForeign('foreign_key_column');
    knex.raw('ALTER TABLE your_table_name DROP CONSTRAINT your_constraint_name');
  });
};

exports.down = function(knex) {
  return knex.schema.alterTable('your_table_name', function(table) {
    table.foreign('foreign_key_column').references('referenced_column').inTable('referenced_table');
    knex.raw('ALTER TABLE your_table_name ADD CONSTRAINT your_constraint_name FOREIGN KEY (your_column_name) REFERENCES referenced_table(referenced_column)');
  });
};

knex migrate:latest