Change default referential action

Problem Associations (foreign keys) in Sequelize define a rather opinionated default referential action for ON UPDATE / ON DELETE clauses.

For ON UPDATE, Sequelize defaults to CASCADE. For ON DELETE, Sequelize defaults to SET NULL if the source field allows null values; otherwise, CASCADE is the default.

It would be convenient to set RESTRICT or NO ACTION as the default (database-wide) in some circumstances. In MySQL, for example, the default referential action is RESTRICT when not explicitly specified; Sequelizes seems to override these defaults.

Describe the solution you’d like It would be nice to override the “default” referential action for ON UPDATE and ON DELETE when associations are created. It can get annoying to override this behavior for every single association in the database if RESTRICT is the general rule / policy. This could be done in the options Object passed to the new Sequelize instance (see usage example below).

Why should this be in Sequelize This is a small change (probably ~10 lines of code), but it gives extra flexibility to the developer without requiring the developer to be verbose with association definitions.

Describe alternatives you’ve considered Another possible solution is creating some sort of hook that allows one to change the default onDelete and onUpdate options of an association. I don’t know of any such hook at this time.

Usage example

const db = new Sequelize(config.database, config.username, config.password, {
	host: config.host,
	// New `associations` key
	associations: {
		onDelete: 'RESTRICT',
		onUpdate: 'CASCADE',
	}
})

[ephys]

We discussed whether to accept this feature request at today’s meeting. We did not feel it was necessary to implement this, as this is already achievable with hooks, and we felt the demand was too low for the extra complexity.

Example of how this can be handled with hooks:

sequelize.afterDefine(model => {
  model.beforeAssociate((data, options) => {
    options.onDelete ||= 'NO ACTION';
  });
});

It’s unfortunately a bit verbose, but you only need to write it once.

We can revisit this at a later date if there is enough demand for it.

[bminer]

Also, thanks to you, I just learned that ||= is a thing in JavaScript.