Workshop 203, Tutorial 3, Step 2, Apex

Integration.cls

public class Integration {

  // The ExternalOrder class holds a string and integer
  // received from the external fulfillment system.

  public class ExternalOrder {
    public String id {get; set;}
    public Integer order_number {get; set;}
  }
    
  // The postOrder method integrates the local Force.com invoicing system 
  // with a remote fulfillment system; specifically, by posting data about 
  // closed orders to the remote system. Functionally, the method 1) prepares 
  // JSON-formatted data to send to the remote service, 2) makes an HTTP call 
  // to send the prepared data to the remote service, and then 3) processes 
  // any JSON-formatted data returned by the remote service to update the 
  // local Invoices with the corresponding external Ids in the remote system.
  
  @future (callout=true) // indicates that this is an asynchronous call
  public static void postOrder(List<Id> invoiceIds) {
    
    // 1) see above

    // Create a JSON generator object
    JSONGenerator gen = JSON.createGenerator(true);
    // open the JSON generator
    gen.writeStartArray();
    // interate through the list of invoices passed in to the call
    // writing each invoice Id to the array
    for (Id invoiceId : invoiceIds) {
      gen.writeStartObject();
      gen.writeStringField('id', invoiceId);
      gen.writeEndObject();            
    }
    // close the JSON generator
    gen.writeEndArray();
    // create a string from the JSON generator
    String jsonOrders = gen.getAsString();
    // debugging call, which you can check in console logs
    System.debug('jsonOrders: ' + jsonOrders);

    // 2) see above 

    // create an HTTPrequest object    
    HttpRequest req = new HttpRequest(); 
    // set up the HTTP request with a method, endpoint, header, and body
    req.setMethod('POST');
    // DON'T FORGET TO UPDATE THE FOLLOWING LINE WITH YOUR appid
    req.setEndpoint('https://{appname}.herokuapp.com/order');
    req.setHeader('Content-Type', 'application/json');
    req.setBody(jsonOrders);    
    // create a new HTTP object
    Http http = new Http();
    // create a new HTTP response for receiving the remote response
    // then use it to send the configured HTTPrequest
    HTTPResponse res = http.send(req);
    // debugging call, which you can check in console logs
    System.debug('Fulfillment service returned '+ res.getBody());
    
    // 3) see above
    
    // Examine the status code from the HTTPResponse
    // If status code != 200, write debugging information, done
    if (res.getStatusCode() != 200) {
      System.debug('Error from ' + req.getEndpoint() + ' : ' + 
        res.getStatusCode() + ' ' + res.getStatus());
    }
    // If status code = 200, update each Invoice Statement
    // with the external ID returned by the fulfillment service.
    else {
      // Retrieve all of the Invoice Statement sObjects 
      // originally passed into the method call to prep for update.           
      List<Invoice__c> invoices = 
        [SELECT Id FROM Invoice__c WHERE Id IN :invoiceIds];
      // Create a list of external orders by deserializing the
      // JSON data returned by the fulfillment service.
      List<ExternalOrder> orders = 
        (List<ExternalOrder>)JSON.deserialize(res.getBody(), 
          List<ExternalOrder>.class);
      // Create a map of Invoice Statement Ids from the retrieved
      // invoices list.
      Map<Id, Invoice__c> invoiceMap = 
        new Map<Id, Invoice__c>(invoices);
      // Update the order numbers in the invoices
      for ( ExternalOrder order : orders ) {
        Invoice__c invoice = invoiceMap.get(order.id);
        invoice.OrderId__c = String.valueOf(order.order_number);
      }
      // Update all invoices in the database with a bulk update
      update invoices;
    }     
  }
}