fix(types): use correct `this` value in getterMethods and setterMethods (#11292)

types/lib/model.d.ts

@@ -1178,15 +1178,15 @@ export interface ModelNameOptions {
 /**
  * Interface for getterMethods in InitOptions
  */
-export interface ModelGetterOptions {
-  [name: string]: (this: Model) => unknown;
+export interface ModelGetterOptions<M extends Model = Model> {
+  [name: string]: (this: M) => unknown;
 }
 
 /**
  * Interface for setterMethods in InitOptions
  */
-export interface ModelSetterOptions {
-  [name: string]: (this: Model, val: any) => void;
+export interface ModelSetterOptions<M extends Model = Model> {
+  [name: string]: (this: M, val: any) => void;
 }
 
 /**
@@ -1477,12 +1477,12 @@ export interface ModelOptions<M extends Model = Model> {
   /**
    * Allows defining additional setters that will be available on model instances.
    */
-  setterMethods?: ModelSetterOptions;
+  setterMethods?: ModelSetterOptions<M>;
 
   /**
    * Allows defining additional getters that will be available on model instances.
    */
-  getterMethods?: ModelGetterOptions;
+  getterMethods?: ModelGetterOptions<M>;
 
   /**
    * Enable optimistic locking.
@@ -1498,7 +1498,7 @@ export interface ModelOptions<M extends Model = Model> {
 /**
  * Options passed to [[Model.init]]
  */
-export interface InitOptions extends ModelOptions {
+export interface InitOptions<M extends Model =  Model> extends ModelOptions<M> {
   /**
    * The sequelize connection. Required ATM.
    */
@@ -1588,7 +1588,7 @@ export abstract class Model<T = any, T2 = any> extends Hooks {
    *  string or a type-description object, with the properties described below:
    * @param options These options are merged with the default define options provided to the Sequelize constructor
    */
-  public static init(attributes: ModelAttributes, options: InitOptions): void;
+  public static init<M extends Model = Model>(this: ModelCtor<M>, attributes: ModelAttributes, options: InitOptions<M>): void;
 
   /**
    * Remove attribute from model definition

types/test/model.ts

@@ -38,11 +38,16 @@ MyModel.init({}, {
     }
   ],
   sequelize,
-  tableName: 'my_model'
+  tableName: 'my_model',
+  getterMethods: {
+    multiply: function() {
+      return this.num * 2;
+    }
+  }
 });
 
 /**
- * Tests for findCreateFind() type. 
+ * Tests for findCreateFind() type.
  */
 class UserModel extends Model {}
 
@@ -56,9 +61,9 @@ UserModel.init({
 UserModel.findCreateFind({
   where: {
     username: "new user username"
-  }, 
+  },
   defaults: {
-    beta_user: true 
+    beta_user: true
   }
 })