Re: JSON support

From: Pierre Brico via curl-users <curl-users_at_lists.haxx.se>
Date: Thu, 20 Jan 2022 15:37:35 +0100

Hi Daniel,

I totally agree with Jeffrey. That isn't the role of curl to worry about
the content of the data sent.

Personally, I very often use curl to write testing scripts. Those scripts
need to deal with JSON to consume REST API. To manipulate the JSON format,
I use the awesome tool jq.

Here is 2 very frequent use-cases:

1/ Building JSON message:

map="transactionAmount=1.00
transactionCurrencyCode=EUR
transactionTrackingCode=$transactionTrackingCode
transactionCallbackUrl=https://website.com/callback
transactionLanguageCode=fr
transactionCountryCode=BE
customerEmail=john.doe_at_email.com"

message=$(echo "$map" |




*jq -Rn '[ inputs | gsub("\r$"; "") | split("="; "") | select(length ==
2) | {(.[0]): .[1]} ] | add'*)

[ $VERBOSE == "Y" ] && echo "$message" | *jq -C "."*

httpCode=$(curl $CURL_OPT -w "%{http_code}" -H "Content-Type:
application/json" "https://$AWS_HOST/$AWS_ENV$API_PAYMENTS" --data
"$message" -o $OUTPUT)

2/ Parsing JSON result

transactionId=$(*jq -r '.transactionId' $OUTPUT*)
echo "Payment transactionId is $transactionId"

The problem with dealing with JSON format is that it can become tricky when
manipulating complex structures with arrays. jq tool does an excellent job
in this domain.


Pierre



On Thu, Jan 20, 2022 at 3:15 PM Jeffrey Walton via curl-users <
curl-users_at_lists.haxx.se> wrote:

> Hi Daniel,
>
> On Thu, Jan 20, 2022 at 8:39 AM Daniel Stenberg via curl-users
> <curl-users_at_lists.haxx.se> wrote:
> >
> > I've been circling around this topic before. On this list I've previously
> > gotten rather lukewarm responses or even several "don't do its", but
> after
> > having asked around people on twitter I think maybe the time might come
> when
> > we add some JSON specific command line options to the tool.
> >
> > I have three reasons why now:
> >
> > 1. Sending JSON has grown to become a very common thing to do in the
> world of
> > REST APIs and more.
> >
> > 2. When asked what features or functionality people like in the many curl
> > "alteratives" that pop up, the "ease of doing JSON" is a frequent answer.
> >
> > 3. A not insignificant amount of people on stackoverflow etc have
> problems to
> > send correct JSON with curl and to get the quoting done right, as json
> uses
> > double-qoutes by itself and shells don't expand variables within single
> quotes
> > etc.
> >
> > I personally am not sending JSON too often myself so I'm pretty sure I'm
> not
> > suitable to design this feature entirely on my own. I need help to
> design this
> > to become as useful as possible.
> >
> > I've drafted my refreshed concept in the curl wiki. To explain it
> shortly, it
> > adds two command line options: one for sending already formatted json as
> a
> > shortcut for -d with the right Accept header, and the other is an option
> for
> > building a json request body to send. See the expanded thoughts here:
> >
> > https://github.com/curl/curl/wiki/JSON
> >
> > That page was previously describing a slightly different json idea, so
> if you
> > looked at it before, look again because it's different now.
> >
> > Is this a good idea? What tweaks does it need to become useful? If you're
> > sending JSON with curl or an alternative tool today, could you see
> yourself
> > using this method instead and what would be needed for that to be really
> > attractive for you?
>
> JSON is presentation layer. I don't think it is core to cURL.
> However... when users have trouble it is often a good idea to help
> them along.
>
> I would consider a design that layers the JSON support on top of cURL.
> Maybe something like a 'curlson' utility. Curlson could do the JSON
> communication using the underlying curl library. Curlson could also
> provide a way to just set a value using positional argument, similar
> to a parameterized query, and without a lot of the shell escaping.
>
> Jeff
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Received on 2022-01-20