Managing API compatibility - Nice3point/RevitTemplates GitHub Wiki

Table of content

Conditional compilation for a specific Revit version
- Examples
Managing Supported Revit Versions
- Solution configurations
- Project configurations
API references

Conditional compilation for a specific Revit version

To write code compatible with different Revit versions, use the directives #if, #elif, #else, #endif.

#if REVIT2026
    //Your code here
#endif

To target a specific Revit version, set the solution configuration in your IDE interface to match that version. E.g., select the Debug R26 configuration for the Revit 2026 API.

The project has available constants such as REVIT2026, REVIT2026_OR_GREATER, REVIT2026_OR_GREATER. Create conditions, experiment to achieve the desired result.

Note

For generating directives, a third-party package is used. You can find more detailed documentation about it here: Revit.Build.Tasks

Examples

To support the latest APIs in legacy Revit versions:

#if REVIT2021_OR_GREATER
    UnitUtils.ConvertFromInternalUnits(69, UnitTypeId.Millimeters);
#else
    UnitUtils.ConvertFromInternalUnits(69, DisplayUnitType.DUT_MILLIMETERS);
#endif

#if REVIT2021_OR_GREATER сompiles a block of code for Revit versions 21, 22, 23 and greater.

To support removed APIs in newer versions of Revit, you can invert the constant:

#if !REVIT2023_OR_GREATER
    var builtinCategory = (BuiltInCategory) category.Id.IntegerValue;
#endif

#if !REVIT2023_OR_GREATER сompiles a block of code for Revit versions 22, 21, 20 and lower.

Managing Supported Revit Versions

To extend or reduce the range of supported Revit API versions, you need to update the solution and project configurations.

Solution configurations

Solution configurations determine which projects are built and how they are configured.

To support multiple Revit versions:

Open the .sln file.
Add or remove configurations for each Revit version.

Example:

GlobalSection(SolutionConfigurationPlatforms) = preSolution
    Debug R24|Any CPU = Debug R24|Any CPU
    Debug R25|Any CPU = Debug R25|Any CPU
    Debug R26|Any CPU = Debug R26|Any CPU
    Release R24|Any CPU = Release R24|Any CPU
    Release R25|Any CPU = Release R25|Any CPU
    Release R26|Any CPU = Release R26|Any CPU
EndGlobalSection

For example Debug R26 is the Debug configuration for Revit 2026 version.

Tip

If you are just ending maintenance for some version, removing the Solution configurations without modifying the Project configurations is enough.

Project configurations

Project configurations define build conditions for specific versions.

To add or remove support:

Open .csproj file
Add or remove configurations for Debug and Release builds.

Example:

<PropertyGroup>
    <Configurations>Debug R24;Debug R25;Debug R26</Configurations>
    <Configurations>$(Configurations);Release R24;Release R25;Release R26</Configurations>
</PropertyGroup>

Important

Edit the .csproj file only manually, IDEs often break configurations.

Then simply map the solution configuration to the project configuration:

Solution and project configuration names may differ, this example uses the same naming style to avoid confusion.

Then specify the framework and Revit version for each configuration, update the .csproj file with the following:

<PropertyGroup Condition="$(Configuration.Contains('R26'))">
    <RevitVersion>2026</RevitVersion>
    <TargetFramework>net8.0-windows</TargetFramework>
</PropertyGroup>

API references

To support CI/CD pipelines and build a project for Revit versions not installed on your computer, use Nuget packages.