Tip: Convert filtered JSON to a CSV

[kellyjonbrazil]

Since jello gives you the full power of the python interpreter, you can not only filter the JSON, but you can also convert the output format to non-native jello output formats, like CSV.

For example, let's take the output of jc -a, which gives us some metadata about the jc program in JSON format. Inside the JSON is an array called parsers that contains the metadata about each parser. Let's use jello to filter just the parsers that are compatible with Windows and output that information as a CSV.

Here is the jello query:

jc -a | jello '\
import io
import csv
q = [p for p in _.parsers if "win32" in p.compatible]
result = io.StringIO(newline="")
fieldnames = ["name", "argument", "version", "description", "author", "author_email",
              "details", "compatible", "magic_commands"]
writer = csv.DictWriter(result, fieldnames=fieldnames)
writer.writeheader()
writer.writerows(q)
print(result.getvalue())' > win32.csv

As you can see, we are simply importing the csv module and writing to a StringIO object with the csv.DictWriter method. The query is assigned to q and used inside the writer.writerows() function. The output is being redirected to a file named win32.csv. We use the print() function to bypass jello's JSON conversion logic.

The output is a standard CSV file:

name,argument,version,description,author,author_email,details,compatible,magic_commands
csv,--csv,1.2,CSV file parser,Kelly Brazil,kellyjonbrazil@gmail.com,Using the python standard csv library,"['linux', 'darwin', 'cygwin', 'win32', 'aix', 'freebsd']",
dig,--dig,2.1,`dig` command parser,Kelly Brazil,kellyjonbrazil@gmail.com,,"['linux', 'aix', 'freebsd', 'darwin', 'win32', 'cygwin']",['dig']
dir,--dir,1.3,`dir` command parser,Rasheed Elsaleh,rasheed@rebelliondefense.com,,['win32'],
env,--env,1.3,`env` command parser,Kelly Brazil,kellyjonbrazil@gmail.com,,"['linux', 'darwin', 'cygwin', 'win32', 'aix', 'freebsd']","['env', 'printenv']"
hosts,--hosts,1.3,`/etc/hosts` file parser,Kelly Brazil,kellyjonbrazil@gmail.com,,"['linux', 'darwin', 'cygwin', 'win32', 'aix', 'freebsd']",

The same can be done with other output-types like YAML, etc.