[GTALUG] Extracting data from JSON file

[Stewart C. Russell]

Hi William,

> I'm writing automated test scripts.  Unfortunately for me, input 
> configuration is XML, and I use "xmlstarlet" to get data from that.

Another one for the XML side is Dan Egnor's xml2. It converts XML to a
simple flat line-oriented format that works well with command line tools:

Trivial XML:

    <xml>
      <blort>squarnk</blort>
      <mlem>-8</mlem>
    </xml>

Examples:

    $ xml2 < triv.xml
    /xml/blort=squarnk
    /xml/mlem=-8

    $ xml2 < triv.xml | grep blort | 2xml
    <xml><blort>squarnk</blort></xml>

Debian packages is "xml2". It would be nice if it had a json filter.
Note that the docs will likely have a bad link. The last docs I've seen
are here:

https://web.archive.org/web/20160812034655/http://dan.egnor.name/xml2/ref

xml2 is a bit old and makes some assumptions about input files that may
not be ideal. xmlstarlet may be the one to stick with.


> The output is JSON, and I need to extract data from that to say
> "Pass" or "Fail".

> Looks like "jq" is the answer.  But, I find that "jq" ignores
> duplicate keys, and accepts only the last one.  Major pain!

Wait, are you saying that the JSON has duplicate hash keys, like this:

    {"blort":"squarnk","mlem":-8,"blort":"phweeen"}

(so, two values for the key "blort")? It really shouldn't do that, even
though the file is valid JSON. Most JSON parsers only return the last value.

cheers,
 Stewart