Working with the Definition File

Accessing parameters in the definition file

Use the following steps to gain access to the definition file and its parameters:

1. Specify the Application.SharedParametersFilename property with an existing text file or a new one.
2. Open the shared parameters file, using the Application.OpenSharedParameterFile() method.
3. Open an existing group or create a new group using the DefinitionFile.Groups property.
4. Open an existing external parameter definition or create a new definition using the DefinitionGroup.Definitions property.

The following classes and methods in the Autodesk.Revit.DB namespace provide access to shared parameters using the Revit API.

• DefinitionFile Class
  • Retrieved using the Application.OpenSharedParameterFile() method. Revit uses one shared parameter file at a time.
  • Represents one shared parameter file.
  • Contains a number of Group objects.
  • Shared parameters are grouped for easy management and contain shared parameter definitions.
  • New definitions can be added as needed.
• ExternalDefinition Class
  • The ExternalDefinition object is created by a DefinitionGroup object from a shared parameter file.
  • External parameter definitions must belong to a Group which is a collection of shared parameter definitions.
• Application.SharedParametersFilename Property
  • Get and set the shared parameter file path using this property.
  • By default, Revit does not have a shared parameter file.
  • Initialize this property before using. If it is not initialized, an exception is thrown.

private void CreateExternalSharedParamFile(string sharedParameterFile)
{
        System.IO.FileStream fileStream = System.IO.File.Create(sharedParameterFile);
        fileStream.Close();
}

private DefinitionFile SetAndOpenExternalSharedParamFile(Autodesk.Revit.ApplicationServices.Application application, string sharedParameterFile)
{
    // set the path of shared parameter file to current Revit
    application.SharedParametersFilename = sharedParameterFile;
    // open the file
    return application.OpenSharedParameterFile();
}

private void ShowDefinitionFileInfo(DefinitionFile myDefinitionFile)
{
    StringBuilder fileInformation = new StringBuilder(500);

    // get the file name 
    fileInformation.AppendLine("File Name: " + myDefinitionFile.Filename);

    // iterate the Definition groups of this file
    foreach (DefinitionGroup myGroup in myDefinitionFile.Groups)
    {
        // get the group name
        fileInformation.AppendLine("Group Name: " + myGroup.Name);

        // iterate the difinitions
        foreach (Definition definition in myGroup.Definitions)
        {
            // get definition name
            fileInformation.AppendLine("Definition Name: " + definition.Name);
        }
    }
    TaskDialog.Show("Revit",fileInformation.ToString());
}

private void ReadEditExternalParam(DefinitionFile file)
{
    // get ExternalDefinition from shared parameter file
    DefinitionGroups myGroups = file.Groups;
    DefinitionGroup myGroup = myGroups.get_Item("MyGroup");
    if (myGroup != null)
    {
        ExternalDefinition myExtDef = myGroup.Definitions.get_Item("MyParam") as ExternalDefinition;
        if (myExtDef != null)
        {
            DefinitionGroup newGroup = myGroups.get_Item("AnotherGroup");
            if (newGroup != null)
            {
                // change the OwnerGroup of the ExternalDefinition
                myExtDef.OwnerGroup = newGroup;
            }
        }
    }
}