Sequelize set timezone to query - postgresql

Question

I'm currently using the Sequelize with postgres in my project. I need to change the query, so it return created_at column with timezone offset.
var sequelize = new Sequelize(connStr, {
dialectOptions: {
useUTC: false //for reading from database
},
timezone: '+08:00' //for writing to database
});
But this affects on entire database. But I need to use timezone for select queries only. Does anyone know how to do that?

Answer 1

This is how I configured it:
dialectOptions: {
dateStrings: true,
typeCast: true,
},
timezone: 'America/Los_Angeles',
http://docs.sequelizejs.com/class/lib/sequelize.js~Sequelize.html

Answer 2

I suggest combining moment.js with one of the following methods:
If you need to parameterize the timezone, then you will probably want to add the offset for each individual query or add an additional field to your table that indicates the timezone, as it does not seem as though sequelize allows parameterized getters.
For example:
const moment = require('moment.js');
const YourModel = sequelize.define('your_model', {
created_at: {
type: Sequelize.DATE,
allowNull: false,
get() {
return moment(this.getDataValue('created_at'))
.utcOffset(this.getDataValue('offset'));
},
},
});
Another possibility would be to extend the model prototype's instance methods in a similar fashion, which allows you to specify the offset at the time that you require the created_at value:
const moment = require('moment.js');
YourModel.prototype.getCreatedAtWithOffset = function (offset) {
return moment(this.created_at).utcOffset(offset);
};

Answer 3

For correct using queries with timezone, prepare your pg driver, see details here:
const pg = require('pg')
const { types } = pg
// we must store dates in UTC
pg.defaults.parseInputDatesAsUTC = true
// fix node-pg default transformation for date types
// https://github.com/brianc/node-pg-types
// https://github.com/brianc/node-pg-types/blob/master/lib/builtins.js
types.setTypeParser(types.builtins.DATE, str => str)
types.setTypeParser(types.builtins.TIMESTAMP, str => str)
types.setTypeParser(types.builtins.TIMESTAMPTZ, str => str)
It's must be initialized before initiating your Sequelize instance.
You can now run a query indicating the timezone for which you want to get the date.
Suppose we make a SQL query, select all User's fields, and "createdAt" in timezone 'Europe/Kiev':
SELECT *, "createdAt"::timestamptz AT TIME ZONE 'Europe/Kiev' AS "createdAt" FROM users WHERE id = 1;
# or with variables
SELECT *, "createdAt"::timestamptz AT TIME ZONE :timezone AS "createdAt" FROM users WHERE id = :id;
For Sequelize (for User model) it will be something like this:
sequelize.findOne({
where: { id: 1 },
attributes: {
include: [
[sequelize.literal(`"User"."createdAt"::timestamptz AT TIME ZONE 'Europe/Kiev'`), 'createdAt'],
// also you can use variables, of course remember about SQL injection:
// [sequelize.literal(`"User"."updatedAt"::timestamptz AT TIME ZONE ${timeZoneVariable}`), 'updatedAt'],
]
}
});