1. new in this version
  2. build a web 2.0 app in happstack
  3. why happstack is cool
  4. getting started with happstack
  5. prerequisites
  6. cabal install me
  7. first shot at happstack
  8. url handling
  9. basic HTML inclusion
  10. templates
  11. stringtemplate basics
  12. debugging
  13. form data: get and post
  14. form data: file uploads
  15. cookies
  16. introduction to macid
  17. first steps with macid
  18. scaling with multimaster
  19. using macid safely
  20. macid dummy data
  21. changing the data model
  22. macid stress test
  23. limitations of macid
  24. foreign characters
  25. IxSets
  26. cron jobs
  27. thanks
  28. appendix (floundering in ghci)

File Uploads

If you want to do file uploads, look at the code that is responsible for adding a profile picture in ControllerPostActions::processformEditConsultantProfile

The same pattern for dealing with form data in the previous chapter holds. The only differences are that

  • the value for the image file that is being passed in via withData is the entire contents of a file, as a bytestring:
    withData $ fd@(EditUserProfileFormData fdContact fdBlurb fdlistAsC fdimagecontents)
  • there is an IO action in the ServerPartT handler, which writes the file:
    liftIO $ writeFileForce avatarpath fdimagecontents
  • enctype="multipart/form-data" in the form itself

In the above, the fdimagecontents variable contents the entire contents of an image file. writeFileForce is just a wrapper over writeFile that creates necessary parent directories if they are missing.

Now for a few words on cookies in Happstack