fix(model): handle true timestamp fields correctly

src/model.js

@@ -1107,16 +1107,28 @@ class Model {
 
     // setup names of timestamp attributes
     if (this.options.timestamps) {
+      for (const key of ['createdAt', 'updatedAt', 'deletedAt']) {
+        if (!['undefined', 'string', 'boolean'].includes(typeof this.options[key])) {
+          throw new Error(`Value for "${key}" option must be a string or a boolean, got ${typeof this.options[key]}`);
+        }
+        if (this.options[key] === '') {
+          throw new Error(`Value for "${key}" option cannot be an empty string`);
+        }
+      }
+
       if (this.options.createdAt !== false) {
-        this._timestampAttributes.createdAt = this.options.createdAt || 'createdAt';
+        this._timestampAttributes.createdAt =
+          typeof this.options.createdAt === 'string' ? this.options.createdAt : 'createdAt';
         this._readOnlyAttributes.add(this._timestampAttributes.createdAt);
       }
       if (this.options.updatedAt !== false) {
-        this._timestampAttributes.updatedAt = this.options.updatedAt || 'updatedAt';
+        this._timestampAttributes.updatedAt =
+          typeof this.options.updatedAt === 'string' ? this.options.updatedAt : 'updatedAt';
         this._readOnlyAttributes.add(this._timestampAttributes.updatedAt);
       }
       if (this.options.paranoid && this.options.deletedAt !== false) {
-        this._timestampAttributes.deletedAt = this.options.deletedAt || 'deletedAt';
+        this._timestampAttributes.deletedAt =
+          typeof this.options.deletedAt === 'string' ? this.options.deletedAt : 'deletedAt';
         this._readOnlyAttributes.add(this._timestampAttributes.deletedAt);
       }
     }

test/integration/model.test.js

@@ -178,6 +178,46 @@ describe(Support.getTestDialectTeaser('Model'), () => {
       expect(defaultFunction.callCount).to.equal(2);
     });
 
+    it('should throw `TypeError` when value for updatedAt, createdAt, or deletedAt is neither string nor boolean', async function () {
+      const modelName = 'UserCol';
+      const attributes = { aNumber: Sequelize.INTEGER };
+
+      expect(() => {
+        this.sequelize.define(modelName, attributes, { timestamps: true, updatedAt: {} });
+      }).to.throw(Error, 'Value for "updatedAt" option must be a string or a boolean, got object');
+      expect(() => {
+        this.sequelize.define(modelName, attributes, { timestamps: true, createdAt: 100 });
+      }).to.throw(Error, 'Value for "createdAt" option must be a string or a boolean, got number');
+      expect(() => {
+        this.sequelize.define(modelName, attributes, { timestamps: true, deletedAt: () => {} });
+      }).to.throw(Error, 'Value for "deletedAt" option must be a string or a boolean, got function');
+    });
+
+    it('should allow me to use `true` as a value for updatedAt, createdAt, and deletedAt fields', async function () {
+      const UserTable = this.sequelize.define(
+        'UserCol',
+        {
+          aNumber: Sequelize.INTEGER
+        },
+        {
+          timestamps: true,
+          updatedAt: true,
+          createdAt: true,
+          deletedAt: true,
+          paranoid: true
+        }
+      );
+
+      await UserTable.sync({ force: true });
+      const user = await UserTable.create({ aNumber: 4 });
+      expect(user['true']).to.not.exist;
+      expect(user.updatedAt).to.exist;
+      expect(user.createdAt).to.exist;
+      await user.destroy();
+      await user.reload({ paranoid: false });
+      expect(user.deletedAt).to.exist;
+    });
+
     it('should allow me to override updatedAt, createdAt, and deletedAt fields', async function () {
       const UserTable = this.sequelize.define(
         'UserCol',