```ruby
class NotificationServices::SlackService < NotificationService
  LABEL = "slack"
  FIELDS += [
    [:service_url, {
      placeholder: 'Slack Hook URL (https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXX/XXXXXXXXX)',
      label:       'Hook URL'
    }]
  ]

  def check_params
    if FIELDS.detect { |f| self[f[0]].blank? }
      errors.add :base, "You must specify your Slack Hook url."
    end
  end

  def message_for_slack(problem)
    "*#{problem.app.name}:* #{problem.message.to_s.lines.first} #{problem_url(problem)}"
  end

  def post_payload(problem)
    payload = {
      :attachments => [
        {
           :fallback => message_for_slack(problem),
           :title => problem.message.to_s.lines.first.truncate(100),
           :title_link => problem_url(problem),
           :text => "*#{problem.app.name}* (#{problem.notices_count} times)",
           :mrkdwn_in => ["text"],
           :color => "#D00000"
        }
      ]
    }
    payload[:channel] = '#staging' if problem.environment == 'staging'
    payload.to_json
  end

  def create_notification(problem)
    HTTParty.post(
      service_url,
      body:    post_payload(problem),
      headers: {
        'Content-Type' => 'application/json'
      }
    )
  end

  def configured?
    service_url.present?
  end
end
```

Use problem.url in Slack notification service.
user
```ruby
class NotificationServices::SlackService < NotificationService
  LABEL = "slack"
  FIELDS += [
    [:service_url, {
      placeholder: 'Slack Hook URL (https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXX/XXXXXXXXX)',
      label:       'Hook URL'
    }]
  ]

  def check_params
    if FIELDS.detect { |f| self[f[0]].blank? }
      errors.add :base, "You must specify your Slack Hook url."
    end
  end

  def message_for_slack(problem)
    "*#{problem.app.name}:* #{problem.message.to_s.lines.first} #{problem.url}"
  end

  def post_payload(problem)
    payload = {
      :attachments => [
        {
           :fallback => message_for_slack(problem),
           :title => problem.message.to_s.lines.first.truncate(100),
           :title_link => problem.url,
           :text => "*#{problem.app.name}* (#{problem.notices_count} times)",
           :mrkdwn_in => ["text"],
           :color => "#D00000"
        }
      ]
    }
    payload[:channel] = '#staging' if problem.environment == 'staging'
    payload.to_json
  end

  def create_notification(problem)
    HTTParty.post(
      service_url,
      body:    post_payload(problem),
      headers: {
        'Content-Type' => 'application/json'
      }
    )
  end

  def configured?
    service_url.present?
  end
end
```
assistant