Re: [Qemu-devel] [PATCH] qmp-shell: fix pretty printing of JSON responses

[Eric Blake]

On 02/22/2016 10:02 AM, Daniel P. Berrange wrote:
> Pretty printing of JSON responses is important to be able
> to understand large responses from query commands in
> particular, eg
> 
> (QEMU) query-chardev
> {   u'return': [   {   u'filename': u'vc',
>                        u'frontend-open': False,
>                        u'label': u'parallel0'},
>                    {   u'filename': u'vc',
>                        u'frontend-open': True,
>                        u'label': u'serial0'},
>                    {   u'filename': u'unix:/tmp/qemp,server',
>                        u'frontend-open': True,
>                        u'label': u'compat_monitor0'}]}
> 
> Unfortunately this was broken during the addition of
> the verbose flag in
> 
>   commit 1ceca07e48ead0dd2e41576c81d40e6a91cafefd
>   Author: John Snow <address@hidden>
>   Date:   Wed Apr 29 15:14:04 2015 -0400
> 
>     scripts: qmp-shell: Add verbose flag
> 
> This is because that change turned the python data
> structure into a formatted JSON string before the
> pretty print was given it. So we're just pretty
> printing a string, which is a no-op.
> 
> This fixes pretty printing of the command responses
> and as an added benefit it will also pretty print
> command arguments in verbose mode
> 
> (QEMU) object-add qom-type=secret id=sec0 props={"data":"123456"}
> {   'arguments': {   'id': 'sec0',
>                      'props': {   u'data': u'123456'},
>                    'qom-type': 'secret'},
>                    'execute': 'object-add'}
>                {   u'return': {   }}

That's an odd mix of regular and Unicode strings.  Any ideas why it is
happening?  But the patch is a strict improvement, so:

Reviewed-by: Eric Blake <address@hidden>

> 
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
>  scripts/qmp/qmp-shell | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/qmp/qmp-shell b/scripts/qmp/qmp-shell
> index 7a402ed..15bbc5e 100755
> --- a/scripts/qmp/qmp-shell
> +++ b/scripts/qmp/qmp-shell
> @@ -231,10 +231,10 @@ class QMPShell(qmp.QEMUMonitorProtocol):
>          return qmpcmd
>  
>      def _print(self, qmp):
> -        jsobj = json.dumps(qmp)
>          if self._pp is not None:
> -            self._pp.pprint(jsobj)
> +            self._pp.pprint(qmp)
>          else:
> +            jsobj = json.dumps(qmp)
>              print str(jsobj)
>  
>      def _execute_cmd(self, cmdline):
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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