feat(types): added optional stricter typing for Model attributes

docs/manual/other-topics/typescript.md

@@ -19,7 +19,21 @@ Example of a minimal TypeScript project:
 import { Sequelize, Model, DataTypes, BuildOptions } from 'sequelize';
 import { HasManyGetAssociationsMixin, HasManyAddAssociationMixin, HasManyHasAssociationMixin, Association, HasManyCountAssociationsMixin, HasManyCreateAssociationMixin } from 'sequelize';
 
-class User extends Model {
+// These are the minimum attributes needed to create a User
+interface UserCreationAttributes {
+  name: string;
+  preferredName: string | null;
+}
+
+// These are all the attributes in the User model
+interface UserAttributes extends UserCreationAttributes {
+  id: number;
+}
+
+// You can choose to omit the `UserAttributes` and `UserCreationAttributes`
+// generic types to simplify your types. This will come at the cost of making
+// typechecking slightly less strict.
+class User extends Model<UserAttributes, UserCreationAttributes> implements UserAttributes {
   public id!: number; // Note that the `null assertion` `!` is required in strict mode.
   public name!: string;
   public preferredName!: string | null; // for nullable fields
@@ -49,7 +63,16 @@ class User extends Model {
 
 const sequelize = new Sequelize('mysql://root:asd123@localhost:3306/mydb');
 
-class Project extends Model {
+interface ProjectAttributes {
+  ownerId: number;
+  name: string;
+}
+
+interface ProjectAttributes extends ProjectCreationAttributes {
+  id: number;
+}
+
+class Project extends Model<ProjectAttributes, ProjectCreationAttributes> implements ProjectAttributes {
   public id!: number;
   public ownerId!: number;
   public name!: string;
@@ -58,7 +81,12 @@ class Project extends Model {
   public readonly updatedAt!: Date;
 }
 
-class Address extends Model {
+interface AddressAttributes {
+  userId: number;
+  address: string;
+}
+
+class Address extends Model<AddressAttributes> implements AddressAttributes {
   public userId!: number;
   public address!: string;
 
@@ -149,21 +177,58 @@ async function stuff() {
 
 ## Usage of `sequelize.define`
 
-TypeScript doesn't know how to generate a `class` definition when we use the `sequelize.define` method to define a Model. Therefore, we need to do some manual work and declare an interface and a type, and eventually cast the result of `.define` to the _static_ type.
+TypeScript doesn't know how to generate a class definition when we use the `sequelize.define` method to define a Model. Therefore, we need to do some manual work and declare a dummy class, derive a static type, and cast the result of `sequelize.define` to the static type.
 
 ```ts
-// We need to declare an interface for our model that is basically what our class would be
-interface MyModel extends Model {
-  readonly id: number;
+// We recommend you declare an interface for the attributes, for stricter typechecking
+interface MyModelAttributes {
+  id: number;
+  name: string;
+}
+
+interface MyModelCreationAttributes extends Optional<MyModelAttributes, 'id'> {}
+
+// We need to declare a class for our model.
+// We and users of this class should never call this. Instead, we only use it
+// to create the static type via the `typeof` call below.
+export class MyModel extends Model<MyModelAttributes, MyModelCreationAttributes> implements MyModelAttributes {
+  public readonly id!: number;
+  public name!: string;
+}
+
+type MyModelStatic = typeof MyModel;
+
+// TS can't derive a proper class definition from a `.define` call, therefor we need to cast here.
+const MyDefineModel = <MyModelStatic>sequelize.define<MyModel>('MyDefineModel', {
+  id: {
+    primaryKey: true,
+    type: DataTypes.INTEGER.UNSIGNED,
+  }
+});
+
+async function stuffTwo() {
+  const myModel = await MyDefineModel.findByPk(1, {
+    rejectOnEmpty: true,
+  });
+  console.log(myModel.id);
 }
+```
 
-// Need to declare the static model so `findOne` etc. use correct types.
-type MyModelStatic = typeof Model & {
-  new (values?: object, options?: BuildOptions): MyModel;
+If you're comfortable with somewhat less strict typing for the attributes on a model, you can save some code by defining the Instance to just extend `Model` without any attributes in the generic types.
+
+```ts
+// We need to declare a class for our model.
+// We and users of this class should never call this. Instead, we only use it
+// to create the static type via the `typeof` call below.
+export class MyModel extends Model {
+  public readonly id!: number;
+  public name!: string;
 }
 
+type MyModelStatic = typeof MyModel;
+
 // TS can't derive a proper class definition from a `.define` call, therefor we need to cast here.
-const MyDefineModel = <MyModelStatic>sequelize.define('MyDefineModel', {
+const MyDefineModel = <MyModelStatic>sequelize.define<MyModel>('MyDefineModel', {
   id: {
     primaryKey: true,
     type: DataTypes.INTEGER.UNSIGNED,

types/index.d.ts

@@ -17,3 +17,9 @@ export { BaseError as Error } from './lib/errors';
 export { useInflection } from './lib/utils';
 export { Utils, QueryTypes, Op, TableHints, IndexHints, DataTypes, Deferrable };
 export { Validator as validator } from './lib/utils/validator-extras';
+
+/**
+ * Type helper for making certain fields of an object optional. This is helpful
+ * for creating the `CreationAttributes` from your `Attributes` for a Model.
+ */
+export type Optional<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;

types/lib/associations/belongs-to-many.d.ts

@@ -104,7 +104,7 @@ export class BelongsToMany<S extends Model = Model, T extends Model = Model> ext
  * The options for the getAssociations mixin of the belongsToMany association.
  * @see BelongsToManyGetAssociationsMixin
  */
-export interface BelongsToManyGetAssociationsMixinOptions extends FindOptions {
+export interface BelongsToManyGetAssociationsMixinOptions extends FindOptions<any> {
   /**
    * A list of the attributes from the join table that you want to select.
    */
@@ -149,9 +149,9 @@ export type BelongsToManyGetAssociationsMixin<TModel> = (
  * @see BelongsToManySetAssociationsMixin
  */
 export interface BelongsToManySetAssociationsMixinOptions
-  extends FindOptions,
-    BulkCreateOptions,
-    InstanceUpdateOptions,
+  extends FindOptions<any>,
+    BulkCreateOptions<any>,
+    InstanceUpdateOptions<any>,
     InstanceDestroyOptions {
   through?: JoinTableAttributes;
 }
@@ -191,9 +191,9 @@ export type BelongsToManySetAssociationsMixin<TModel, TModelPrimaryKey> = (
  * @see BelongsToManyAddAssociationsMixin
  */
 export interface BelongsToManyAddAssociationsMixinOptions
-  extends FindOptions,
-    BulkCreateOptions,
-    InstanceUpdateOptions,
+  extends FindOptions<any>,
+    BulkCreateOptions<any>,
+    InstanceUpdateOptions<any>,
     InstanceDestroyOptions {
   through?: JoinTableAttributes;
 }
@@ -233,9 +233,9 @@ export type BelongsToManyAddAssociationsMixin<TModel, TModelPrimaryKey> = (
  * @see BelongsToManyAddAssociationMixin
  */
 export interface BelongsToManyAddAssociationMixinOptions
-  extends FindOptions,
-    BulkCreateOptions,
-    InstanceUpdateOptions,
+  extends FindOptions<any>,
+    BulkCreateOptions<any>,
+    InstanceUpdateOptions<any>,
     InstanceDestroyOptions {
   through?: JoinTableAttributes;
 }
@@ -274,7 +274,7 @@ export type BelongsToManyAddAssociationMixin<TModel, TModelPrimaryKey> = (
  * The options for the createAssociation mixin of the belongsToMany association.
  * @see BelongsToManyCreateAssociationMixin
  */
-export interface BelongsToManyCreateAssociationMixinOptions extends CreateOptions {
+export interface BelongsToManyCreateAssociationMixinOptions extends CreateOptions<any> {
   through?: JoinTableAttributes;
 }
 /**
@@ -455,7 +455,7 @@ export type BelongsToManyHasAssociationsMixin<TModel, TModelPrimaryKey> = (
  * The options for the countAssociations mixin of the belongsToMany association.
  * @see BelongsToManyCountAssociationsMixin
  */
-export interface BelongsToManyCountAssociationsMixinOptions extends Transactionable, Filterable {
+export interface BelongsToManyCountAssociationsMixinOptions extends Transactionable, Filterable<any> {
   /**
    * Apply a scope on the related model, or remove its default scope by passing false.
    */

types/lib/associations/belongs-to.d.ts

@@ -30,7 +30,7 @@ export class BelongsTo<S extends Model = Model, T extends Model = Model> extends
  * The options for the getAssociation mixin of the belongsTo association.
  * @see BelongsToGetAssociationMixin
  */
-export interface BelongsToGetAssociationMixinOptions extends FindOptions {
+export interface BelongsToGetAssociationMixinOptions extends FindOptions<any> {
   /**
    * Apply a scope on the related model, or remove its default scope by passing false.
    */
@@ -61,7 +61,7 @@ export type BelongsToGetAssociationMixin<TModel> = (options?: BelongsToGetAssoci
  * The options for the setAssociation mixin of the belongsTo association.
  * @see BelongsToSetAssociationMixin
  */
-export interface BelongsToSetAssociationMixinOptions extends SaveOptions {
+export interface BelongsToSetAssociationMixinOptions extends SaveOptions<any> {
   /**
    * Skip saving this after setting the foreign key if false.
    */
@@ -95,7 +95,8 @@ export type BelongsToSetAssociationMixin<TModel, TPrimaryKey> = (
  * The options for the createAssociation mixin of the belongsTo association.
  * @see BelongsToCreateAssociationMixin
  */
-export interface BelongsToCreateAssociationMixinOptions extends CreateOptions, BelongsToSetAssociationMixinOptions {}
+export interface BelongsToCreateAssociationMixinOptions
+  extends CreateOptions<any>, BelongsToSetAssociationMixinOptions {}
 
 /**
  * The createAssociation mixin applied to models with belongsTo.

types/lib/associations/has-many.d.ts

@@ -36,7 +36,7 @@ export class HasMany<S extends Model = Model, T extends Model = Model> extends A
  * The options for the getAssociations mixin of the hasMany association.
  * @see HasManyGetAssociationsMixin
  */
-export interface HasManyGetAssociationsMixinOptions extends FindOptions {
+export interface HasManyGetAssociationsMixinOptions extends FindOptions<any> {
   /**
    * Apply a scope on the related model, or remove its default scope by passing false.
    */
@@ -74,7 +74,7 @@ export type HasManyGetAssociationsMixin<TModel> = (options?: HasManyGetAssociati
  * The options for the setAssociations mixin of the hasMany association.
  * @see HasManySetAssociationsMixin
  */
-export interface HasManySetAssociationsMixinOptions extends FindOptions, InstanceUpdateOptions {}
+export interface HasManySetAssociationsMixinOptions extends FindOptions<any>, InstanceUpdateOptions<any> {}
 
 /**
  * The setAssociations mixin applied to models with hasMany.
@@ -110,7 +110,7 @@ export type HasManySetAssociationsMixin<TModel, TModelPrimaryKey> = (
  * The options for the addAssociations mixin of the hasMany association.
  * @see HasManyAddAssociationsMixin
  */
-export interface HasManyAddAssociationsMixinOptions extends InstanceUpdateOptions {}
+export interface HasManyAddAssociationsMixinOptions extends InstanceUpdateOptions<any> {}
 
 /**
  * The addAssociations mixin applied to models with hasMany.
@@ -146,7 +146,7 @@ export type HasManyAddAssociationsMixin<TModel, TModelPrimaryKey> = (
  * The options for the addAssociation mixin of the hasMany association.
  * @see HasManyAddAssociationMixin
  */
-export interface HasManyAddAssociationMixinOptions extends InstanceUpdateOptions {}
+export interface HasManyAddAssociationMixinOptions extends InstanceUpdateOptions<any> {}
 
 /**
  * The addAssociation mixin applied to models with hasMany.
@@ -182,7 +182,7 @@ export type HasManyAddAssociationMixin<TModel, TModelPrimaryKey> = (
  * The options for the createAssociation mixin of the hasMany association.
  * @see HasManyCreateAssociationMixin
  */
-export interface HasManyCreateAssociationMixinOptions extends CreateOptions {}
+export interface HasManyCreateAssociationMixinOptions extends CreateOptions<any> {}
 
 /**
  * The createAssociation mixin applied to models with hasMany.
@@ -218,7 +218,7 @@ export type HasManyCreateAssociationMixin<TModel> = (
  * The options for the removeAssociation mixin of the hasMany association.
  * @see HasManyRemoveAssociationMixin
  */
-export interface HasManyRemoveAssociationMixinOptions extends InstanceUpdateOptions {}
+export interface HasManyRemoveAssociationMixinOptions extends InstanceUpdateOptions<any> {}
 
 /**
  * The removeAssociation mixin applied to models with hasMany.
@@ -254,7 +254,7 @@ export type HasManyRemoveAssociationMixin<TModel, TModelPrimaryKey> = (
  * The options for the removeAssociations mixin of the hasMany association.
  * @see HasManyRemoveAssociationsMixin
  */
-export interface HasManyRemoveAssociationsMixinOptions extends InstanceUpdateOptions {}
+export interface HasManyRemoveAssociationsMixinOptions extends InstanceUpdateOptions<any> {}
 
 /**
  * The removeAssociations mixin applied to models with hasMany.
@@ -362,7 +362,7 @@ export type HasManyHasAssociationsMixin<TModel, TModelPrimaryKey> = (
  * The options for the countAssociations mixin of the hasMany association.
  * @see HasManyCountAssociationsMixin
  */
-export interface HasManyCountAssociationsMixinOptions extends Transactionable, Filterable {
+export interface HasManyCountAssociationsMixinOptions extends Transactionable, Filterable<any> {
   /**
    * Apply a scope on the related model, or remove its default scope by passing false.
    */

types/lib/associations/has-one.d.ts

@@ -28,7 +28,7 @@ export class HasOne<S extends Model = Model, T extends Model = Model> extends As
  * The options for the getAssociation mixin of the hasOne association.
  * @see HasOneGetAssociationMixin
  */
-export interface HasOneGetAssociationMixinOptions extends FindOptions {
+export interface HasOneGetAssociationMixinOptions extends FindOptions<any> {
   /**
    * Apply a scope on the related model, or remove its default scope by passing false.
    */
@@ -59,7 +59,7 @@ export type HasOneGetAssociationMixin<TModel> = (options?: HasOneGetAssociationM
  * The options for the setAssociation mixin of the hasOne association.
  * @see HasOneSetAssociationMixin
  */
-export interface HasOneSetAssociationMixinOptions extends HasOneGetAssociationMixinOptions, SaveOptions {
+export interface HasOneSetAssociationMixinOptions extends HasOneGetAssociationMixinOptions, SaveOptions<any> {
   /**
    * Skip saving this after setting the foreign key if false.
    */
@@ -93,7 +93,7 @@ export type HasOneSetAssociationMixin<TModel, TModelPrimaryKey> = (
  * The options for the createAssociation mixin of the hasOne association.
  * @see HasOneCreateAssociationMixin
  */
-export interface HasOneCreateAssociationMixinOptions extends HasOneSetAssociationMixinOptions, CreateOptions {}
+export interface HasOneCreateAssociationMixinOptions extends HasOneSetAssociationMixinOptions, CreateOptions<any> {}
 
 /**
  * The createAssociation mixin applied to models with hasOne.