Flash Messages

# Flash messages

You can show messages using flash. A flash message is a simple String that is passed between two actions. This lets a user know if an action was a success or a failure. (e.g. “Record was saved successfully”)

# Type safe flash messages

The built-in message types are success, failure and info. Using these will cause compile-time errors if you accidentally mistype something. It is recommended to stick to these whenever possible.

# In an action
flash.success = "It worked!"
flash.failure = "That did not work"
flash.info = "Be cool"

These will be rendered by the flash component in src/components/shared/flash_messages.cr. The flash component was mounted from your MainLayout and AuthLayout (found in src/pages/).

You can modify the layout or the component to add HTML classes, change where flash is rendered, etc.

# Setting other messages

The built-in messages are success, failure and info, but you can use anything you’d like:

flash.set("something_special", "Super spesh")
flash.get("something_special") # => "Super spesh"

# Persisting flash messages through redirect

By default, flash messages are cleared whenever redirect is called. This is illustrated below:

  class Home::Index < BrowserAction
    get "/" do
      if current_user
        flash.failure = "I won't show, because we're using a redirect!"
        redirect to: Me::Show
      else
        flash.success = "I will show, because we're rendering a page!"
        html Home::IndexPage
      end
    end
  end

To show flash messages through a redirect, we must leverage the flash.keep method:

class Home::Index < BrowserAction
  get "/" do
    if current_user
      flash.keep
      flash.success = "Now I will show, because of flash.keep!"
      redirect to: Me::Show
    else
      flash.success = "I will show, because we're rendering without calling a new action!"
      html Home::IndexPage
    end
  end
end