[jira] [Comment Edited] (TIKA-3286) Tika does not issue an error when language file doesn't exist; not supporting script files

["Peter Kronenberg (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TIKA-3286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17275265#comment-17275265 ] 

Peter Kronenberg edited comment on TIKA-3286 at 1/29/21, 7:05 PM:
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Well, it would be even earlier if we throw the exception before even calling Tesseract.  I've been playing with code to check for the files, and it works fine.  Since Tika is supposed to be a wrapper to make calling Tesseract easier, I think it's fine for Tika to do some pre-checking before even calling Tesseract.  And that way, we don't get stuck if Tesseract changes the format of their messages


was (Author: peterkronenberg):
Well, it would be even earlier if we throw the exception before even calling Tika.  I've been playing with code to check for the files, and it works fine.  Since Tika is supposed to be a wrapper to make calling Tesseract easier, I think it's fine for Tika to do some pre-checking before even calling Tesseract.  And that way, we don't get stuck if Tesseract changes the format of their messages

> Tika does not issue an error when language file doesn't exist; not supporting script files
> ------------------------------------------------------------------------------------------
>
>                 Key: TIKA-3286
>                 URL: https://issues.apache.org/jira/browse/TIKA-3286
>             Project: Tika
>          Issue Type: Improvement
>            Reporter: Peter Kronenberg
>            Priority: Major
>         Attachments: list-lang.png, nolang.png, script.png
>
>
> Tika uses a regular expression to validate the language string, assuming it is set of  ISO-639-2 language code separated by plus signs.  However, Script files (in the _script_ directory) can have any arbitrary name, with the only rule being that they start with a capital letter.  The scripts were introduced in 4.0.0, [https://github.com/manisandro/gImageReader/issues/323]
>  
> In addition, if the user specifies an invalid language (i.e., the string matches the regular expression, but there is no corresponding language file in Tessdata), no error message is issued.  Tesseract issues some very ugly and misleading messages which simply assume that you haven't set the _tessdata_ directory correctly, but they are not captured by Tika (and not sure they would be appropriate anyway).  Tika just blindly calls Tesseract but then doesn't get any output back.
>   !nolang.png!
> I suggest parsing the language string by the plus sign and not doing any other validating on the string, but instead, actually checking to see that the file exists in either _tessdata_ or _tessdata/script_.
> If any of them don’t exists, then throw an exception, similar to what is done now when the language doesn't match the regular expression.
> I've started to prototype this.
>  
> Later: I'm trying to clarify how the scripts are intended to be used.  The page referenced above as well as [https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#LANGUAGES |https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#LANGUAGES]imply that the _-l_ option accepts the name of a language or script.  I assumed it would look in _tessdata_ first and if not found, would look in _tessdata/script_.  But it seems you have to enter the path.
>   !script.png!
> _tesseract --list-lang_ displays them this way
>   !list-lang.png!
> so it clearly knows about the _script_ directory.  But it expects the user to know it as well.  Not sure if we want to make Tika work more friendly



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