eu.vaadinonkotlin.vaadin8

Class LoginForm

eu.vaadinonkotlin.vaadin8.LoginForm

public class LoginForm

A simple login form which shows a simple login form; calls a handler provided in the LoginForm.onLogin when user clicks the "Sign In" button.

There are two ways to use this form. If the whole app is user-protected (an user must log in to view any view of the app, there are no views that an anonymous user may view), then it is simply possible to show the form as a full-screen in the UI if no user is logged in:

class MyUI : UI() {
  override fun init(request: VaadinRequest) {
    if (Session.loggedInUser == null) {
      content = LoginView()
      return;
    } else {
      content = MainLayout()  // create a main layout, populate the menu, etc
      navigator = Navigator(this, content as ViewProvider)
      navigator.addProvider(autoViewProvider)
      VokSecurity.install()
      // you need to install the error handler which would handle AccessRejectedException
  }
}

class LoginView : VerticalLayout() {
  init {
     setSizeFull()
     loginForm("My App") {
       alignment = Alignment.MIDDLE_CENTER
       onLogin { username, password ->
         val user = User.findByUsername(username)
         if (user == null) {
           usernameField.componentError = UserError("The user does not exist")
         } else if (!user.passwordMatches(password)) {
           passwordField.componentError = UserError("Invalid password")
         } else {
           Session.loggedInUser = user
           Page.getCurrent().reload()  // this will cause the UI to be re-created, but the user is now logged in so the MainLayout should be instantiated etc.
         }
       }
     }
  }
}

If only parts of the app are protected, you may simply show the LoginForm class in a Window, when your app-specific login button is pressed.

See Also:

LoginForm.onLogin

Constructor Summary

Constructors

Constructor and Description
LoginForm(java.lang.String appName) A simple login form which shows a simple login form; calls a handler provided in the LoginForm.onLogin when user clicks the "Sign In" button.

Method Summary

Modifier and Type	Method and Description
com.vaadin.ui.Label	getAppNameLabel()
com.vaadin.ui.Button	getLoginButton()
com.vaadin.ui.TextField	getPasswordField()
com.vaadin.ui.TextField	getUsernameField()
void	onLogin(kotlin.jvm.functions.Function2<? super java.lang.String,? super java.lang.String,kotlin.Unit> loginHandler) The loginHandler will try to log in the user with given username and password. Both are not blank and trimmed. If such user does not exist, or the password does not match, just set the appropriate UserError to LoginForm.getUsernameField or passwordField and bail out. Else, log in the user (e.g. by storing the user into the session) and reload the page (com.vaadin.server.Page.reload) (so that the UI is re-created and redraws the welcome page for the user, if the entire app is user-protected), or navigate to the user's welcome view.

Constructor Detail

LoginForm

public LoginForm(java.lang.String appName)

A simple login form which shows a simple login form; calls a handler provided in the LoginForm.onLogin when user clicks the "Sign In" button.

There are two ways to use this form. If the whole app is user-protected (an user must log in to view any view of the app, there are no views that an anonymous user may view), then it is simply possible to show the form as a full-screen in the UI if no user is logged in:

class MyUI : UI() {
  override fun init(request: VaadinRequest) {
    if (Session.loggedInUser == null) {
      content = LoginView()
      return;
    } else {
      content = MainLayout()  // create a main layout, populate the menu, etc
      navigator = Navigator(this, content as ViewProvider)
      navigator.addProvider(autoViewProvider)
      VokSecurity.install()
      // you need to install the error handler which would handle AccessRejectedException
  }
}

class LoginView : VerticalLayout() {
  init {
     setSizeFull()
     loginForm("My App") {
       alignment = Alignment.MIDDLE_CENTER
       onLogin { username, password ->
         val user = User.findByUsername(username)
         if (user == null) {
           usernameField.componentError = UserError("The user does not exist")
         } else if (!user.passwordMatches(password)) {
           passwordField.componentError = UserError("Invalid password")
         } else {
           Session.loggedInUser = user
           Page.getCurrent().reload()  // this will cause the UI to be re-created, but the user is now logged in so the MainLayout should be instantiated etc.
         }
       }
     }
  }
}

If only parts of the app are protected, you may simply show the LoginForm class in a Window, when your app-specific login button is pressed.

See Also:

LoginForm.onLogin

Method Detail

getAppNameLabel

public com.vaadin.ui.Label getAppNameLabel()

getUsernameField

public com.vaadin.ui.TextField getUsernameField()

getPasswordField

public com.vaadin.ui.TextField getPasswordField()

getLoginButton

public com.vaadin.ui.Button getLoginButton()

onLogin

public void onLogin(kotlin.jvm.functions.Function2<? super java.lang.String,? super java.lang.String,kotlin.Unit> loginHandler)

The loginHandler will try to log in the user with given username and password. Both are not blank and trimmed. If such user does not exist, or the password does not match, just set the appropriate UserError to LoginForm.getUsernameField or passwordField and bail out. Else, log in the user (e.g. by storing the user into the session) and reload the page (com.vaadin.server.Page.reload) (so that the UI is re-created and redraws the welcome page for the user, if the entire app is user-protected), or navigate to the user's welcome view.

See Also:

LoginForm.getUsernameField