Adds support for updating invoices via HTTP POST

README.textile

@@ -230,6 +230,15 @@ Invoice and line item totals are calculated automatically.
 		invoice.create</code></pre>
 
 
+
+h3. POST /api.xro/2.0/invoice
+
+Updates an existing invoice record.
+<pre><code>    invoice_retrieved_from_xero.due_date = Date.today
+    invoice_retrieved_from_xero.save</code></pre>
+
+
+
 h3. PUT /api.xro/2.0/invoices
 
 Inserts multiple invoices for a specific organization in Xero (currently only adding new invoices is allowed).

lib/xero_gateway/gateway.rb

@@ -197,21 +197,24 @@ def build_invoice(invoice = {})
     #
     #    create_invoice(invoice)
     def create_invoice(invoice)
-      request_xml = invoice.to_xml
-      response_xml = http_put(@client, "#{@xero_url}/Invoices", request_xml)
-      response = parse_response(response_xml, {:request_xml => request_xml}, {:request_signature => 'PUT/invoice'})
-
-      # Xero returns invoices inside an <Invoices> tag, even though there's only ever
-      # one for this request
-      response.response_item = response.invoices.first
-
-      if response.success? && response.invoice && response.invoice.invoice_id
-        invoice.invoice_id = response.invoice.invoice_id 
-      end
-
-      response
+      save_invoice(invoice)
     end
-
+
+    #
+    # Updates an existing Xero invoice
+    #
+    # Usage : 
+    #
+    # invoice = xero_gateway.get_invoice(some_invoice_id)
+    # invoice.due_date = Date.today
+    #
+    # xero_gateway.update_invoice(invoice)  
+
+    def update_invoice(invoice)
+      raise "invoice_id is required for updating invoices" if invoice.invoice_id.nil?
+      save_invoice(invoice)
+    end
+
     #
     # Creates an array of invoices with a single API request.
     # 
@@ -425,6 +428,35 @@ def save_contact(contact)
       response
     end
 
+    # Create or update an invoice record based on if it has an invoice_id.
+    def save_invoice(invoice)
+      request_xml = invoice.to_xml
+
+      response_xml = nil
+      create_or_save = nil
+      if invoice.invoice_id.nil?
+        # Create new invoice record.
+        response_xml = http_put(@client, "#{@xero_url}/Invoices", request_xml, {})
+        create_or_save = :create
+      else
+        # Update existing invoice record.
+        response_xml = http_post(@client, "#{@xero_url}/Invoices", request_xml, {})
+        create_or_save = :save
+      end
+
+      response = parse_response(response_xml, {:request_xml => request_xml}, {:request_signature => "#{create_or_save == :create ? 'PUT' : 'POST'}/invoice"})
+
+      # Xero returns invoices inside an <Invoices> tag, even though there's only ever
+      # one for this request
+      response.response_item = response.invoices.first
+
+      if response.success? && response.invoice && response.invoice.invoice_id
+        invoice.invoice_id = response.invoice.invoice_id 
+      end
+
+      response
+    end
+
     def parse_response(raw_response, request = {}, options = {})
 
       response = XeroGateway::Response.new

lib/xero_gateway/invoice.rb

@@ -209,10 +209,14 @@ def ==(other)
       return true
     end
 
-    # General purpose createsave method.
-    # If contact_id and contact_number are nil then create, otherwise, attempt to save.
+    # General purpose create/save method.
+    # If invoice_id is nil then create, otherwise, attempt to save.
     def save
-      create
+      if invoice_id.nil?
+        create
+      else
+        update
+      end
     end
 
     # Creates this invoice record (using gateway.create_invoice) with the associated gateway.
@@ -222,19 +226,24 @@ def create
       gateway.create_invoice(self)
     end
 
-    # Alias create as save as this is currently the only write action.
-    alias_method :save, :create
-
+    # Updates this invoice record (using gateway.update_invoice) with the associated gateway.
+    # If no gateway set, raise a Xero::Invoice::NoGatewayError exception.
+    def update
+      raise NoGatewayError unless gateway
+      gateway.update_invoice(self)
+    end
+
     def to_xml(b = Builder::XmlMarkup.new)
       b.Invoice {
+        b.InvoiceID self.invoice_id if self.invoice_id
+        b.InvoiceNumber self.invoice_number if invoice_number
         b.Type self.invoice_type
+        b.CurrencyCode self.currency_code if self.currency_code
         contact.to_xml(b)
         b.Date Invoice.format_date(self.date || Date.today)
         b.DueDate Invoice.format_date(self.due_date) if self.due_date
         b.Status self.invoice_status if self.invoice_status
-        b.InvoiceNumber self.invoice_number if invoice_number
         b.Reference self.reference if self.reference
-        b.CurrencyCode self.currency_code if self.currency_code
         b.LineAmountTypes self.line_amount_types
         b.LineItems {
           self.line_items.each do |line_item|
@@ -253,7 +262,6 @@ def self.from_xml(invoice_element, gateway = nil, options = {})
           when "InvoiceNumber" then invoice.invoice_number = element.text            
           when "Type" then invoice.invoice_type = element.text
           when "CurrencyCode" then invoice.currency_code = element.text
-          when "Type" then invoice.invoice_type = element.text
           when "Contact" then invoice.contact = Contact.from_xml(element)
           when "Date" then invoice.date = parse_date(element.text)
           when "DueDate" then invoice.due_date = parse_date(element.text)

test/integration/update_invoice_test.rb

@@ -0,0 +1,31 @@
+require File.dirname(__FILE__) + '/../test_helper'
+
+class UpdateInvoiceTest < Test::Unit::TestCase
+  include TestHelper
+
+  def setup
+    @gateway = XeroGateway::Gateway.new(CONSUMER_KEY, CONSUMER_SECRET)
+
+    if STUB_XERO_CALLS
+      @gateway.xero_url = "DUMMY_URL"
+
+      @gateway.stubs(:http_put).with {|client, url, body, params| url =~ /Invoices$/ }.returns(get_file_as_string("create_invoice.xml"))          
+      @gateway.stubs(:http_post).with {|client, url, body, params| url =~ /Invoices$/ }.returns(get_file_as_string("invoice.xml"))          
+    end
+  end
+
+  def test_update_invoice
+    invoice = @gateway.create_invoice(dummy_invoice).invoice
+
+    today = Date.today
+    invoice.due_date = today
+
+    result = @gateway.update_invoice(invoice)
+
+    assert result.success?
+    assert !result.request_xml.nil?
+    assert !result.response_xml.nil?    
+    assert_equal invoice.invoice_id, result.invoice.invoice_id
+    assert_equal today, result.invoice.due_date if !STUB_XERO_CALLS
+  end
+end