Is it possible to put associations in their model definitions too?

[Hiroki111]

I found that if I don't put all the associations (hasMany, etc) into one file, I get the following error.

   throw new Error(`${this.name}.belongsToMany called with something that's not a subclass of Sequelize.Model`);
   ^
Error: users.belongsToMany called with something that's not a subclass of Sequelize.Model
  at Function.belongsToMany (C:\app\node_modules\sequelize\lib\associations\mixin.js:49:13)
  at Object.<anonymous> (C:\app\models\/user.ts:51:6)

I solved it by putting all the associations into one file. This solution was found from this post on Stackoverflow.

Still, I don't think it's a good approach, because

1. If you want to know about a model, you have to check model/user.ts and model/index.ts.
2. model/index.ts can be quite huge if you have many entities with associations.

Is it possible to put associations seperately?