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Pattern — Custom File Type

Files are UObject classes. When the player double-clicks in Explorer, the OS launches the file’s Target Program Class. Bundled video and audio files demonstrate the pattern.

flowchart LR
  File["BP_File_MyDoc<br/><i>UOperatingSystemFile</i>"]
  Prog["BP_Prog_MyEditor<br/><i>UOperatingSystemBaseProgram</i>"]
  Explorer["UOperatingSystemExplorer"]
  File -->|"Extension: .mydoc"| Explorer
  File -->|"Target Program Class"| Prog
  Explorer -->|"On Open"| Prog

Bundled file examples

File class	Extension	Target program	Path
`BP_File_SampleVideo`	`.mp4`	`BP_Prog_VideoPlayer`	`Shared/Blueprints/Files/`
`BP_File_Audio_01`	`.mp3`	`BP_Prog_AudioPlayer`	`Shared/Blueprints/Files/Audio/`
`BP_File_WelcomeNote`	`.txt`	Notepad	`Shared/Blueprints/Files/`

Screenshot callouts

Runtime file creation

Get Operating System → Get Directory From Path
  → Construct File (Class: BP_File_MyDoc, Parent Directory: …)