Re: [libmicrohttpd] POST processing "any" mime type

[Christian Grothoff]

On 11/24/2011 11:16 AM, Andreas Wehrmann wrote:
> I noticed that MHD_create_post_processor() refuses to create a processor
> when the
> MIME type is not "application/x-www-form-urlencoded" or
> "multipart/form-data".

Right, that is the documented and intended behavior.

> However, I'd like to post process data of a different type (i.e.
> "application/json").
> I could do this manually in the access handler of course,
> but I would like to reuse the mechanism that libmicrohttpd already
> implements.

I'm not sure how that would work or what the benefit would be.  To begin 
with, the MHD_PostDataIterator is supposed to supply a *key* argument 
(note that that argument is not allowed to be NULL), which would not be 
known for an unknown mime type.

> In the case for MIME types for which the library doesn't implement any
> handling,
> it could just call the user function directly, providing the content type.
>
> What do you think?

I think this would be an incompatible API change (existing applications 
may rely on this function 'failing' for odd encoding types) and it 
should be trivial for you to implement whatever behavior you desire if 
you get the 'failing' (NULL) return value from 
'MHD_create_post_processor' (simply query the mime type yourself and 
call your handler, that's 2 lines of code).

Not to mention, typically I would expect that your code knows which 
encoding to expect (at least Json vs. form-data) and thus you'd know 
which way to process the data to begin with.  And if you know that you 
have a data format that requires a specific parser (like Json), why 
would you want to involve the MHD_PostProcessor in the first place -- as 
it can do nothing useful for you (note that the PostProcessor does NOT 
buffer the data to give you the "entire" upload).  As far as I see it, 
passing the data via the PostProcessor would just add a few useless 
indirections in cases where the PostProcessor parser is not suitable.

Happy hacking,

Christian