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Use this documentation when building your Tekla Structures apps

Code example: Custom property plug-in

Updated: 12 Jun 2023

Custom property plug-ins are programmed tools for calculating template values used in reporting and drawings. The following steps create a basic custom property plug-in that uses Windows Forms.

After downloading the TSOpenAPIExamples package from GitHub (button above), find CustomPropertyTest example at \CustomProperties\CustomPropertyTest.

Create a basic custom property plug-in

  1. In Microsoft Visual Studio, create a new project. Select Class Library(.Net framework) as template and enter a name for your project.

  2. Add Tekla API assemblies to your project as references.

  3. Rename Class1.cs to CustomProperty.cs (this could be a more specific name). Edit CustomProperty.cs:

    • Add assemblies needed:

      using System.ComponentModel.Composition;
      using Tekla.Structures.Model;
      using Tekla.Structures.CustomPropertyPlugin;

      Custom property functionality is using Managed Extensibility Framework (MEF) for loading custom property assemblies, therefore a reference to System.ComponentModel.Composition assembly is needed in the project.

    • Define needed metadata for custom property: 

      [ExportMetadata("CustomProperty", "CUSTOM.NAME_OF_THE_PROPERTY")] 
    • Implement the ICustomPropertyPlugin interface: 

      //Methods in the interface are passing object ID as argument. 
      //Identifier of the object can be constructed using the ID in order to utilize 
      //the functionality in Tekla.Structures.Model assembly.
      public class CustomPropertyTest : ICustomPropertyPlugin 
          //Return custom property int value for object.
          public int GetIntegerProperty(int objectId) 
              return -1 * objectId; 
          //Return string value for object.
          public string GetStringProperty(int objectId) 
              return "Hello " + objectId.ToString(); 
          //Return double value for object.
          public double GetDoubleProperty(int objectId) 
              return (double)(-1 * objectId); 

Test example application

  1. In Microsoft Visual Studio, open and build project CustomProperty.cs to create the .dll file. The file is located at \Examples\CustomProperties\CustomPropertyTest.
  2. Copy the .dll file created to \environments\common\extensions\custom\properties\
  3. Check if the plug-in loads:

    • Open a model in Tekla Structures, on the File menu, click Logs and select session history log. From the list you can see if your plug-in has loaded.