Merge pull request #1288 from tajpouria/patch-1

Updated -- authentication.md Clarify passport-local default behavior

Author: kamilmysliwiec

content/techniques/authentication.md

@@ -262,6 +262,8 @@ export class LocalStrategy extends PassportStrategy(Strategy) {
 
 We've followed the recipe described earlier for all Passport strategies. In our use case with passport-local, there are no configuration options, so our constructor simply calls `super()`, without an options object.
 
+> info **Hint** We can pass an options object in the call to `super()` to customize the behavior of the passport strategy. In this example, the passport-local strategy by default expects properties called `username` and `password` in the request body.  Pass an options object to specify different property names, for example: `super({{ '{' }} usernameField: 'email' {{ '}' }})`.  See the [Passport documentation](http://www.passportjs.org/docs/configure/) for more information.
+
 We've also implemented the `validate()` method. For each strategy, Passport will call the verify function (implemented with the `validate()` method in `@nestjs/passport`) using an appropriate strategy-specific set of parameters. For the local-strategy, Passport expects a `validate()` method with the following signature: `validate(username: string, password:string): any`.
 
 Most of the validation work is done in our `AuthService` (with the help of our `UsersService`), so this method is quite straightforward. The `validate()` method for **any** Passport strategy will follow a similar pattern, varying only in the details of how credentials are represented. If a user is found and the credentials are valid, the user is returned so Passport can complete its tasks (e.g., creating the `user` property on the `Request` object), and the request handling pipeline can continue. If it's not found, we throw an exception and let our <a href="exception-filters">exceptions layer</a> handle it.