Added getInvoice() method

src/classes/XeroAccountingApi.cls

@@ -113,6 +113,33 @@ public with sharing class XeroAccountingApi {
         return xeroInvoices;
     }
 
+    /**
+    *   @author Ben Edwards ([email protected])
+    *   @description Method to return a single invoice for your Xero environment for a given Xero Invoice
+    *   @return Single Xero Invoice
+    **/
+    public static XeroInvoice getInvoice (String invoiceId) {
+
+        XeroInvoice xeroInvoice = new XeroInvoice();
+
+        // Execute the callout to the Invoice resource
+        HttpResponse response = XeroCalloutUtility.executeCallout('GET', 'Invoices/' + invoiceId, null);
+
+        // If successful response
+        if (response.getStatusCode() == 200) {
+
+            // Use the parser to convert the response into Xero objects
+            xeroInvoice = XeroCalloutResponseParser.parseInvoices(response.getBody())[0];
+        }
+        else {
+
+            // Raise error
+            throw new XeroAccountingApiException(response.getStatusCode() + ': ' + response.getBody());
+        }
+
+        return xeroInvoice;
+    }
+
     /**
     *   @author Ben Edwards ([email protected])
     *   @description Method to return all invoices for a given Contact Id

src/classes/XeroInvoice.cls

@@ -55,14 +55,15 @@ public class XeroInvoice {
 	class cls_ContactPersons {
 	}
 	class LineItem {
+		public String ItemCode;
 		public String Description;	//Consulting services as agreed
-		public Integer UnitAmount;	//120
+		public Decimal UnitAmount;	//120
 		public String TaxType;	//NONE
-		public Integer TaxAmount;	//0
-		public Integer LineAmount;	//600
+		public Decimal TaxAmount;	//0
+		public Decimal LineAmount;	//600
 		public String AccountCode;	//200
 		public cls_Tracking[] Tracking;
-		public Integer Quantity;	//5
+		public Decimal Quantity;	//5
 		public String LineItemID;	//0d129d0d-4b3a-4567-afc5-0453f3457175
 		public cls_ValidationErrors[] ValidationErrors;
 	}