How to use external assemblies with custom user functions in the Report Designer

HOW-TO
How to use external assemblies with custom user functions in Telerik Report Designer

DESCRIPTION
It is a common requirement to add your own User Functions or bind to custom CLR objects, data models (such as an OpenAccess ORM model), external assemblies with custom data source objects, data feeds (including OData), and web services.

In order to expose your data, so it can be utilized by the Object/OpenAccess/Entity data source components, or extend the default behavior of the Telerik Reporting engine with custom user functions, you have to use the AssemblyReferences Element of the Telerik.Reporting configuration section to reference your custom assembly:

SOLUTION

Create an assembly with Custom User Functions

• Open Visual Studio and create a new Class Library project named MyAssembly.
• Add a reference to Telerik.Reporting.dll. When the assembly is used in the Report Designer its version will be resolved according to the Report Designer version of Telerik Reporting assemblies.
• Create your custom User Functions by adding a new MyClass object to the project and the following lines of code formatting a string input:

C#

VB.NET

• Build your project.

Extend Telerik Report Designer configuration

Once the assembly with our custom logic is built it should be placed in the folder or a subfolder of the Report Designer executable file. The default installation folder is C:\Program Files (x86)\Telerik\Reporting QX XXXX\Report Designer (C:\Program Files\Telerik\Reporting QX XXXX\Report Designer on 32 bit machines), where X XXXX stands for the release version and year, e.g Q1 2013.

• Locate the Report Designer executable and its configuration file on your machine (Telerik.ReportDesigner.exe and Telerik.ReportDesigner.exe.config)
• Place MyAssembly.dll into the folder or a subfolder of where Telerik.ReportDesigner.exe resides.

• Open with a text editor the Report Designer’s configuration file and navigate to the <AssemblyReferences> element.
• Uncomment the section and change the name attribute to MyAssembly. Notice that the assembly is referred only by its name without specifying the extension:
  <!-- Add assembly references -->

    

  <!--

  <Telerik.Reporting>

      <AssemblyReferences>

          <add name="MyFunctions" version="1.0.0.0" />

      </AssemblyReferences>

  </Telerik.Reporting>

  -->
  Note: Additionally you can add culture and publicKeyToken attributes to identify the assembly in the <add> element if necessary.

A possible configuration extending the Report Designer with the functionality in MyAssembly.dll assembly.

The Report Designer will look for MyAssembly.dll in its own folder (i.e. where resides Telerik.ReportDesigner.exe) and in MySubDir and MySubDir\SubDir (using the specified relative paths in the .NET <probing> element).

• Reopen the Report Designer and explore the extended functionality

Use assembly located in non relative path

Telerik.Reporting AssemblyReferences section is trying to load the assemblies according the .NET rules. Thus in order to use a signed assembly located in directory different from the application directory or GAC you have to add dependentAssembly section to point the .NET framework where to look for the assembly with the user functions/aggregates. For more information check out the CodeBase Element MSDN article.

IMPORTANT: If the external assembly extending the Report Designer depends on other assemblies, all related assemblies have to be placed in the folder where the Report Designer is located.

IMPORTANT: In order to deploy report that uses external assembly check out the Deploying trdx (XML report definition) that uses external assembly KB article.