[FR] Regex Failure gives Does Not Exist condition

[Servinjesus1]

Currently, failing a regex check in a custom wildcard returns the input field unaltered. I think this is odd behavior since optional wildcards exist. These allow for users to do e.g. {%1} | {%t} if their custom wildcard %1 tries to regex the title field, and they really want the title field back undoctored if their regex fails, but only if the custom wildcard returns a "does not exist" condition rather than its current behavior. I'm not sure what DNE looks like in a Zotfile wildcard (an empty string?), but I could imagine it feasible to make regex evaluations return this if there's no match.

For reference, the naming scheme I'm striving for will do something like: Scientist1993-JJ~Mitochondr...house_Cell

by default, but if the field Name exists: Scientist1993-JJ~Mitochondria_Powers_Cells

I've got it down to: {%b~}{ {%1} | { {%2} { %3 | {...%4} } } }/

where %1 would be the custom field Name. If that does not yet exist, default to %2, a regex for the first 10 "interesting" characters of the title², plus %3, a regex for the last 10 "interesting" characters of the title, if the title is 20 "interesting" characters long, otherwise ...%4, roll up the middle part and keep the last 10 "interesting" characters. To get this done, I would need this Regex DNE feature and this feature.

[gabrielkulp]

I agree pretty strongly with this. In my case, I want a naming scheme that behaves differently based on if the BBT citation key is pinned. You can easily check if the citation key is pinned by checking the extra field, but i think it might be impossible because:

"If the match fails, this operation returns the input data"

Here's my current custom wildcard attempt that doesn't work as expected:

{"1": {"field": "extra", "operations": [{"function": "exec", "regex": "(Citation Key: )(\\w*|\\d*)", "group": 2}] } }

And here is an example naming rule that relies on the expected behavior: {%1|%t}{ - %a}{ - %y}

In this specific case, an alternative solution would be a first-class "pinned citationkey" wildcard that's blank when unpinned, but I imagine that wouldn't be so nice because of the BBT dependency. I think a lightweight solution is to make failed matches count as empty fields.

[Servinjesus1]

Workaround is to use regex replacement, not exec. This more powerful tool does multiple matching, so you can define something like:

    "1":
    {
        "field": "title",
        "operations":
        [
            {
                "function": "replace",
                "regex": "(^.{10}).*(.{14}$)",
                "replacement": "$1..$2"
            }
        ]
    }

as one of your custom replacement rules. In this case, it truncates anything longer than 24 characters to <first 10>..<last 14>.