Format specifiers: how to use the "alternatives" thing with the "conditional" specifier?

[Nuthouse01]

I am struggling to get the exact behavior I want out of the format strings. I would like to pull images from Sankaku; if the "tags_character" field exists, I want to join the first several of them; if it does not exist, then I would like a string such as "NONE" to be used. Based on this post I know that I can get the behavior I want by listing alternatives in the configuration file, but I really feel like this should be possible with only one formatter string...

Here is what I've tried so far (assuming that tags_character does not exist):
{tags_character[0]|'NONE'}
result NONE, but does not have the joining behavior.
{tags_character[0:5]:J+/|'NONE'}
result "error, can only join an iterable"
{tags_character[0:5]|'NONE':J+/}
result N+O+N+E, lol
{tags_character[0:5]:?//J+/|'NONE'}
result empty (I think this might be a bug? The description of the "alternative" operator implies that if the left side is an empty string or invalid, then it should choose the right side...)

So, is this a bug, or intended/expected behavior? If this is intended, is there any way to get this default behavior in only one formatter string, or am I forced to use the branching behavior in the config file?

[mikf]

Well, this is "expected" behavior, but it should definitely be improved.

The correct way of specifying NONE as alternative would be
{tags_character[0:5]|'NONE':J+/}
but applying J, i.e. str.join(), to another string results in N+O+N+E,
so you are currently forced to use the branching behavior.

I will push a commit that changes this behavior to not join strings, only lists, the next time I do a git push.

[mikf]

Fixed in commit 6990ad0, so you can now actually use {tags_character[0:5]|'NONE':J+/} in the next release and it will work as expected.