Improve developer experience setting up TypeScript with Sequelize

What are you doing?

I’m adding sequelize as a reference to my package/project and compiling it with TypeScript.

What do you expect to happen?

A successful compilation

What is actually happening?

I’ve obtained some errors that told me some types were missing. I solved this adding them as dependencies. Should you include @types/bluebird and @types/validator on the sequelize package? The error was the following:

node_modules/sequelize/types/lib/promise.d.ts:2:27 - error TS7016: Could not find a declaration file for module ‘bluebird’. ‘C:/Users/X/Documents/Y/Z/node_modules/bluebird/js/release/bluebird.js’ implicitly has an ‘any’ type. Try npm install @types/bluebird if it exists or add a new declaration (.d.ts) file containing declare module 'bluebird';

2 import * as Bluebird from ‘bluebird’; ~~~~~~~~~~

node_modules/sequelize/types/lib/utils/validator-extras.d.ts:2:22 - error TS7016: Could not find a declaration file for module ‘validator’. ‘C:/Users/X/Documents/Y/Z/node_modules/validator/index.js’ implicitly has an ‘any’ type. Try npm install @types/validator if it exists or add a new declaration (.d.ts) file containing declare module 'validator';

2 import * as val from ‘validator’;

Dialect: mariadb Dialect version: XXX Database version: XXX Sequelize version: 5.2.8

[matushorvath]

@papb If you don’t want to bloat the package for non-TS users, I suggest you separate the types to a @types/sequelize package and make that package depend on @types/bluebird and @types/validator. That would both provide working types and reduce bloat for non-TS users to a minimum.

The way it is packaged now, we get the worst of both worlds:

• non-TS users get 320 kB of types installed automatically as part of the sequelize package
• TS users get broken types that can’t be used unless you do manual steps, which is very nonstandard in npm world

I respectfully ask that you reconsider this approach.

[papb]

For TypeScript usage, you need to manually install the following packages: @types/node, @types/validator and @types/bluebird. This is documented on our TypeScript Tutorial.

We know that this tutorial is a bit hard to find. This is already known and there is already an open PR to improve this: #10677

Thanks for using Sequelize 😬