Refactoring two node-accessing methods

Question

I cannot edit the QueryPermissions class because it is an external .dll that was given to me to use. Yes, I realize it's a bad practice to use an out variables, but I am pushing for a rewrite of that service.

As you can see below the two methods do the almost the EXACT same thing only one uses a groupkey and the other uses a userkey and then calls the appropriate method. For whatever reason I am drawing a blank on refactoring these methods.

public IEnumerable<Node> GetNodesForUser(int userKey, IEnumerable<OnlineReport> onlineReports)
{
 var nodes = new List<Node>();
 foreach (var onlineReport in onlineReports)
 {
 var parentNode = new Node {Text = onlineReport.Key, Value = onlineReport.Value};
 var webQueries = new List<WebQuery>();
 //Line that is different
 _QueryPermissions.GetQueriesForTaskAndUser(Int32.Parse(onlineReport.Value), userKey, ref webQueries, true);
 foreach (var childNode in webQueries.Select(webQuery => new Node(parentNode){Text = webQuery.QueryTitle, Value = webQuery.QueryKey.ToString()}))
 {
 parentNode.Children.Add(childNode);
 }
 nodes.Add(parentNode);
 }
 return nodes;
}
public IEnumerable<Node> GetNodesForGroup(int groupKey, IEnumerable<OnlineReport> onlineReports)
{
 var nodes = new List<Node>();
 foreach (var onlineReport in onlineReports)
 {
 var parentNode = new Node { Text = onlineReport.Key, Value = onlineReport.Value };
 var webQueries = new List<WebQuery>();
 //Line that is different
 _QueryPermissions.GetQueriesForTaskAndUserGroup(Int32.Parse(onlineReport.Value), groupKey, ref webQueries, true);
 foreach (var childNode in webQueries.Select(webQuery => new Node(parentNode) { Text = webQuery.QueryTitle, Value = webQuery.QueryKey.ToString() }))
 {
 parentNode.Children.Add(childNode);
 }
 nodes.Add(parentNode);
 }
 return nodes;
}

Answer 1

The big difference between the functions is not the userKey vs. groupKey but rather than they have different queries embedded in them

_QueryPermissions.GetQueriesForTaskAndUser(Int32.Parse(onlineReport.Value), userKey, ref webQueries, true);

vs.

_QueryPermissions.GetQueriesForTaskAndUserGroup(Int32.Parse(onlineReport.Value), groupKey, ref webQueries, true);

It looks like these can be abstracted as

 delegate void NodeQueryDelegate(int reportValue, int key, ref List<WebQuery> webQueries, bool someBool);

so it should be possible to refactor thus

public IEnumerable<Node> GetNodesFromQuery(int key, IEnumerable<OnlineReport> onlineReports, NodeQueryDelegate query) {
 var nodes = new List<Node>();
 foreach (var onlineReport in onlineReports) {
 var parentNode = new Node { Text = onlineReport.Key, Value = onlineReport.Value };
 var webQueries = new List<WebQuery>();
 //Line that is different
 query(Int32.Parse(onlineReport.Value), key, ref webQueries, true);
 foreach (var childNode in webQueries.Select(webQuery => new Node(parentNode) { Text = webQuery.QueryTitle, Value = webQuery.QueryKey.ToString() })) {
 parentNode.Children.Add(childNode);
 }
 nodes.Add(parentNode);
 }
 return nodes;
}

Getting the user nodes becomes

var userNodes = GetNodesFromQuery(userKey, onlineReports, _QueryPermissions.GetQueriesForTaskAndUser);

Getting the group node

var groupNodes = GetNodesFromQuery(groupKey, onlineReports, _QueryPermissions.GetQueriesForTaskAndUserGroup);

Answer 2

What about using a delegate?

private delegate void Query(int value, int key, ref List<WebQuery>, bool b);
public void SomeCallingMethod()
{
 IEnumerable<OnlineReport> reports;
 // one way
 int myUserKey;
 Query q = _QueryPermissions.GetQueriesForTaskAndUser;
 var returnValue = GetNodesForUser(q, myUserKey, reports);
 //or the other
 int groupKey;
 q = _QueryPermissions.GetQueriesForTaskAndUserGroup;
 returnValue = GetNodesForUser(q, groupKey, reports);
}
public IEnumerable<Node> GetNodesForUser(Query query, int key, IEnumerable<OnlineReport> onlineReports)
{
 var nodes = new List<Node>();
 foreach (var onlineReport in onlineReports)
 {
 var parentNode = new Node { Text = onlineReport.Key, Value = onlineReport.Value };
 var webQueries = new List<WebQuery>();
 //Line that is different
 // _QueryPermissions.GetQueriesForTaskAndUser(Int32.Parse(onlineReport.Value), userKey, ref webQueries, true);
 query.Invoke(Int32.Parse(onlineReport.Value), key, ref webQueries, true);
 foreach (var childNode in webQueries.Select(webQuery => new Node(parentNode) { Text = webQuery.QueryTitle, Value = webQuery.QueryKey.ToString() }))
 {
 parentNode.Children.Add(childNode);
 }
 nodes.Add(parentNode);
 }
 return nodes;
}