An example of using Lift's Wiring feature to build an invoice system.

input goes here

Add

Subtotal: subtotal

Tax Rate:

Taxable: taxable

Tax: Tax

Total: Total

The code for managing the invoice page is very simple. We define the relationship between the data:

case class Line(guid: String, name: String, price: Double, taxable: Boolean)

  private object Info {
    val invoices = ValueCell(List(newLine))
    val taxRate = ValueCell(0.05d)
    val subtotal = invoices.lift(_.foldLeft(0d)(_ + _.price))
    val taxable = invoices.lift(_.filter(_.taxable).
                                foldLeft(0D)(_ + _.price))

    val tax = taxRate.lift(taxable) {_ * _}

    val total = subtotal.lift(tax) {_ + _}    
  }

Next we create snippets to display the data:

  def subtotal(in: NodeSeq) = WiringUI.asText(in, Info.subtotal)

  def taxable(in: NodeSeq) = WiringUI.asText(in, Info.taxable)

  def tax(in: NodeSeq) = WiringUI.asText(in, Info.tax, JqWiringSupport.fade)

  def total(in: NodeSeq) = WiringUI.asText(in, Info.total, JqWiringSupport.fade)

And hook the snippets into our view:

  <div>Subtotal: <span class="lift:InvoiceWiring.subtotal">subtotal</span></div>

  <div>Tax Rate: <input class="lift:InvoiceWiring.taxRate"></div>

  <div>Taxable: <span class="lift:InvoiceWiring.taxable">taxable</span></div>

  <div>Tax: <span class="lift:InvoiceWiring.tax">Tax</span></div>

  <div>Total: <span class="lift:InvoiceWiring.total">Total</span></div>

And each time any of the cells changes, the display is automatically updated.