ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Desktop.Core Namespace / GeneralOptions Class / ProjectCreateInFolder Property
Example Version

ProjectCreateInFolder Property
Gets and sets whether to store the project file, project geodatabase, and project toolbox in a folder named for the project.
Syntax
public bool ProjectCreateInFolder {get; set;}
Remarks
If ProjectCreateInFolder is set to true (the default), then a subfolder named for the project will be created (within whatever is the location being used for the new project). If ProjectCreateInFolder is set to false then project default files are stored in the default project location without organizing them into their own folder.
Example
Get GeneralOptions
var startMode = ApplicationOptions.GeneralOptions.StartupOption;
var aprx_path = ApplicationOptions.GeneralOptions.StartupProjectPath;

var hf_option = ApplicationOptions.GeneralOptions.HomeFolderOption;
var folder = ApplicationOptions.GeneralOptions.CustomHomeFolder;

var gdb_option = ApplicationOptions.GeneralOptions.DefaultGeodatabaseOption;
var def_gdb = ApplicationOptions.GeneralOptions.CustomDefaultGeodatabase;

var tbx_option = ApplicationOptions.GeneralOptions.DefaultToolboxOption;
var def_tbx = ApplicationOptions.GeneralOptions.CustomDefaultToolbox;

var create_in_folder = ApplicationOptions.GeneralOptions.ProjectCreateInFolder;
Set GeneralOptions to Use Custom Settings
//Set the application to use a custom project, home folder, gdb, and toolbox
//In each case, the custom _path_ must be set _first_ before 
//setting the "option". This ensures the application remains 
//in a consistent state. This is the same behavior as on the Pro UI.
if (string.IsNullOrEmpty(ApplicationOptions.GeneralOptions.StartupProjectPath))
  ApplicationOptions.GeneralOptions.StartupProjectPath = @"D:\data\usa.aprx";//custom project path first
ApplicationOptions.GeneralOptions.StartupOption = StartProjectMode.WithDefaultProject;//option to use it second

if (string.IsNullOrEmpty(ApplicationOptions.GeneralOptions.CustomHomeFolder))
  ApplicationOptions.GeneralOptions.CustomHomeFolder = @"D:\home_folder";//custom home folder first
ApplicationOptions.GeneralOptions.HomeFolderOption = OptionSetting.UseCustom;//option to use it second

if (string.IsNullOrEmpty(ApplicationOptions.GeneralOptions.CustomDefaultGeodatabase))
  ApplicationOptions.GeneralOptions.CustomDefaultGeodatabase = @"D:\data\usa.gdb";//custom gdb path first
ApplicationOptions.GeneralOptions.DefaultGeodatabaseOption = OptionSetting.UseCustom;//option to use it second

if (string.IsNullOrEmpty(ApplicationOptions.GeneralOptions.CustomDefaultToolbox))
  ApplicationOptions.GeneralOptions.CustomDefaultToolbox = @"D:\data\usa.tbx";//custom toolbox path first
ApplicationOptions.GeneralOptions.DefaultToolboxOption = OptionSetting.UseCustom;//option to use it second
Set GeneralOptions to Use Defaults
//Default options can be set regardless of the value of the "companion"
//path (to a project, folder, gdb, toolbox, etc.). The path value is ignored if
//the option setting does not use it. This is the same behavior as on the Pro UI.
ApplicationOptions.GeneralOptions.StartupOption = StartProjectMode.ShowStartPage;
ApplicationOptions.GeneralOptions.HomeFolderOption = OptionSetting.UseDefault;
ApplicationOptions.GeneralOptions.DefaultGeodatabaseOption = OptionSetting.UseDefault;
ApplicationOptions.GeneralOptions.DefaultToolboxOption = OptionSetting.UseDefault;//set default option first

//path values can (optionally) be set (back) to null if their 
//"companion" option setting is the default option.
if (ApplicationOptions.GeneralOptions.StartupOption != StartProjectMode.WithDefaultProject)
  ApplicationOptions.GeneralOptions.StartupProjectPath = null;
if (ApplicationOptions.GeneralOptions.HomeFolderOption == OptionSetting.UseDefault)
  ApplicationOptions.GeneralOptions.CustomHomeFolder = null;
if (ApplicationOptions.GeneralOptions.DefaultGeodatabaseOption == OptionSetting.UseDefault)
  ApplicationOptions.GeneralOptions.CustomDefaultGeodatabase = null;
if (ApplicationOptions.GeneralOptions.DefaultToolboxOption == OptionSetting.UseDefault)
  ApplicationOptions.GeneralOptions.CustomDefaultToolbox = null;
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also