accessing-project-nodes.md

Accessing project nodes

Before reading this page, please make sure to have the concept of InformationModel and Session.

Navigating to a node

The Node.Get syntax

The Get method is used to fetch nodes from the current project, it can retrieve both session and global objects (nodes), this method also accepts a type that will be passed to the variable type

• Example:
  • var myButton = … .Get<Button>("path/to/button"); -> Will create a myButton variable of Type FTOptix.UI.Button pointing to the desired element
• After the object has been casted to the proper path, you can access its properties using IntelliSense
  • Example:
    • myButton.Text = Hello;

Accessing global objects

In order to manipulate any project element, you first need to access it, this can be either done by getting its NodeId or its node object

• Examples:

  • var myNodeId = Project.Current.Get( [path/to/node] ).NodeId;

  • var myObject = Project.Current.Get( [path/to/node] );

  • Where path/to/node can be obtained by right clicking any element of the IDE and then clicking Copy path to node, here you need to remember to remove the project name from the pasted element

    • Example:
      • NewHMIProject25/Model/MyCustomMotor --> Model/MyCustomMotor

Accessing session-based objects

Now that we know how session works, it's easy to understand the benefits of placing a NetLogic in a session-based object (such as the page you want to access or manipulate) and then use the relative addressing to retrieve the right element - Example: - var ButtonText = Owner.Get("MotorButton/Text");

The Node.Find syntax

You can also search for a specific object by knowing its BrowseName by using the Find method, this can be useful but it is not recommended as it is very slow to perform (it will recursively browse the whole project until it gets to the first element with such node)

• Example:
  • var myObj = Project.Current.Find("ObjectName");

Casting vs Type passing

Passing the object type

Type parameter can be used with "generic methods" that allows using different types. A generic method can be called either without an argument (anything that applies to any node such as BrowseName or NodeId) or by specifying the type of argument within angle brackets

• Example:
  • var myfolder = Project.Current.Get<Folder>("Model\MyFolder");

Using this type passing option, the returned node is null if:

• Node does not exist
• The node does not match the specified type (e.g: MyFolder is an Object and not a Folder)

Casting from IUANode

A cast is an explicit conversion, to perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. - Example: - var myfolder = (Folder)Project.Current.Get("Model\MyFolder");

Using this casting option, the node is returned as null only if completely missing, if the object type cannot be casted, an exception is thrown.

Summary

Result is very similar, as best practice we suggest to use the type passing approach unless casting is a specific requirement to achieve the result

Accessing an object by NodeId (pointer)

/// <summary>
/// Access an object by passing a NodeId pointer to a NetLogic variable. This keeps references valid even if the object is moved in the project tree.
/// </summary>
// Example: assume a NodeId variable named "ObjectPointer" exists and contains the NodeId of the target object
var myObjectNodeId = LogicObject.GetVariable("ObjectPointer").Value;
var myRectangle = InformationModel.Get<Rectangle>(myObjectNodeId);
// Now use myRectangle as the referenced object

Use ChildrenRemoteRead to inspect an aliased object structure

/// <summary>
/// When an object is aliased (for example via an Alias pointer), `ChildrenRemoteRead` lets you fetch a lightweight view
/// of the aliased object's children without creating full session objects. This is handy to read a structure's values.
/// </summary>
// Example: assume `LightPointer` is an alias variable pointing to a UI object.
var refLight = LogicObject.GetAlias("LightPointer");
if (refLight != null)
{
    var structure = refLight.ChildrenRemoteRead();
    Log.Info("IntermittentMode value: " + structure.SingleOrDefault(item => item.RelativePath == "IntermittentMode").Value);
}

Count nodes under a specific page/object

/// <summary>
/// Count the number of nodes under a given NodeId and log the result.
/// Input: NodeId of the starting node.
/// Output: Logs the count to Info.
/// </summary>
[ExportMethod]
public static int GetNodesNumber(NodeId nodeId) => InformationModel.Get(nodeId).FindNodesByType<IUANode>().Count();

[ExportMethod]
public void CounNodes()
{
    // Example: log node counts for two screens
    var unit02 = Project.Current.Get("UI/Screens/Pages/Un02/Em02_Pref/Unit02Em02");
    var unit00 = Project.Current.Get("UI/Screens/Pages/Un00/Unit00");

    Log.Info("Unit02Em02: " + GetNodesNumber(unit02.NodeId).ToString());
    Log.Info("Unit00: " + GetNodesNumber(unit00.NodeId).ToString());
}