Allow export command to create subfolders via file format

[simonfrey]

This change allows to create subfolders via the --format flag.

In order to allow controlledcreation of subfolders and not accidentally do it when there is a / in the format the new flag --allow-subfolder-creation needs to be set to enable this feature.

Without setting the flag the behavior of the command is equal to before.

Edit: Thanks to @captncraig this uses a template function for format now instead of the less secure way with the flag

[sh0rez]

Hey that's super cool! Thanks for you contribution.

I think a slightly shorter flag name would make this a bit easier to use (see above) :)

[captncraig]

Hah! I did this myself in a local branch to test things. I like the idea of a flag to enable it. But I can also see why it is dangerous in the first place. Tanka runs the replace, probably to cover things like labels or whatnot having slashes and getting put into file paths.

So is there a way to allow explicit path breaks in a format sting, without accidentally getting path breaks from malformed data inside the templates?

My dirty solution was to use ~ as an indicator in a format string that you want a path break there, and do the replace like so:

name := strings.Replace(buf.String(), "/", "-", -1)
name = strings.Replace(name, "~", string(os.PathSeparator), -1)

To add safety, perhaps a template function to put in some even more unlikely string so you don't accidentally use it. Maybe something like that would allow this functionality without a new flag?

[simonfrey]

Ah thats a great idea with the template function. Will check it out and report later on

[simonfrey]

Awesome that works even better and is super intuitive :D Just insert the {{mkdir}} into the template. I use rune(7) that is the no printable bel character and thereby should never be in in any string.

[simonfrey]

Anything else left to do?

[sh0rez]

Hey @simonfrey, sorry for the delay here.

I talked about this with @malcolmholmes and we both feel the mkdir part feels a bit unnatural inside of the template.

What he suggested instead, is to replace all occurences of / in the template before evaluation with rune(7). Then running the template, you can replace all returned slashes with - (like it is already), making sure no directories are created accidentally.

Finally, you replace all rune(7) with / again. This way, explicit slashes are used as directories, all other are replaced by dashes.

Let me know if that sounds good to you as well, happy to discuss :)

[simonfrey]

Tried it and it feels more natural. Added the change

[sh0rez]

Looking good! Some nits and we are good to go :)