Feature request: allow join to read from stdin

[mloughran]

For my current use case it would be extremely convenient to be able to pipe stdin to xsv join.

Example use case

xsv frequency -s typeId relationships.csv | xsv join value - id types.csv

It would also allow multiple joins to be piped together.

Potential interface: Since the filename arguments cannot be optional without breaking the interface, this could work similarly to cat for example, where - is used to signify stdin.

I have never written a line of rust, but happy to attempt a PR if this proposal seems sensible.

P.S. Thanks for an amazing tool!

[pol3waf]

This feature would be very helpful in my work, too.
It would be great if you could use something like:
xsv join column_1 <( xsv search -s "argument_1" <my_file_1> ) column_2 <( xsv search -s "argument_2" <my_file_2> )
If I use this command, the first row (containing the headers) will be joined but then an "Illegal seek (os error 29)" error occurs.

Otherwise I would have to save the searches first and then perform a join on both files. In my case this is troublesome, because the my TSV files contain fields with JSON markup and xsv introduces more commas as delimiters than I can handle.
So yes, this feature would be great!

PS: A big thank you for this amazing tool!

[kyleflan]

Found this issue as I wanted to do the same thing as @mloughran.

This doesn't help @pol3waf's use case, but instead of using -, you can use /dev/stdin if you only need one file from stdin, e.g..

xsv search -s Population '[0-9]' worldcitiespop.csv \
    | xsv join --no-case Country /dev/stdin Abbrev countrynames.csv \
    | xsv select 'Country[1],AccentCity,Population' \
    | xsv sample 10 \
    | xsv table