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From: Pavel Stehule <pavel.stehule@gmail.com>
Date: Tue, 19 Jan 2016 19:09:06 +0100
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 <CAFj8pRCHZmLKiYpGmdbFYeeqK8PQ9u0acQ6W4vU9TshO2J=4wQ@mail.gmail.com>
Subject: Re: remove null values from json
To: Michael Moore <michaeljmoore@gmail.com>
Cc: postgres list <pgsql-sql@postgresql.org>
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2016-01-15 21:24 GMT+01:00 Michael Moore <michaeljmoore@gmail.com>:

> This is ALMOST what I want:
> select json_strip_nulls ('[{ "f1":1 , "f2":null  , "f3":"NULL" , "f4":""
>  }]');
> the result is:
> "[{"f1":1,"f3":"NULL","f4":""}]"
>
> As you can see, the "f2" object has been removed. I would *also* like to
> remove the f3 and f4 objects.
>
> I realize I won't be able to use the json_strip_nulls function to do this.
> I could brute force it by doing "json to array" then looping through the
> array and picking only the objects I want, and then using the chosen
> objects to build an new JSON document.
>
> I suspect there is a more elegant way to accomplish the same objective.
> Ideas?
>

if you generate JSON from zero, then replace "" and "NULL" by NULL before
jsonification.

Pavel


>
> PS. It would be great to have a json_strip_values (json, array) where
> array contains the list of values you want removed.
>

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><div class=3D"gmail_quo=
te">2016-01-15 21:24 GMT+01:00 Michael Moore <span dir=3D"ltr">&lt;<a href=
=3D"mailto:michaeljmoore@gmail.com" target=3D"_blank">michaeljmoore@gmail.c=
om</a>&gt;</span>:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0=
 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">This =
is ALMOST what I want:<br><font face=3D"monospace, monospace">select json_s=
trip_nulls (&#39;[{ &quot;f1&quot;:1 , &quot;f2&quot;:null =C2=A0, &quot;f3=
&quot;:&quot;NULL&quot; , &quot;f4&quot;:&quot;&quot; =C2=A0}]&#39;);</font=
><br><div>the result is:</div><div><font face=3D"monospace, monospace">&quo=
t;[{&quot;f1&quot;:1,&quot;f3&quot;:&quot;NULL&quot;,&quot;f4&quot;:&quot;&=
quot;}]&quot;</font><br></div><div><br></div><div>As you can see, the &quot=
;f2&quot; object has been removed. I would <b>also</b> like to remove the f=
3 and f4 objects.=C2=A0</div><div><br></div><div>I realize I won&#39;t be a=
ble to use the json_strip_nulls function to do this. I could brute force it=
 by doing &quot;json to array&quot; then looping through the array and pick=
ing only the objects I want, and then using the chosen objects to build an =
new JSON document.=C2=A0</div><div><br></div><div>I suspect there is a more=
 elegant way to accomplish the same objective.</div><div>Ideas?</div></div>=
</blockquote><div><br></div><div>if you generate JSON from zero, then repla=
ce &quot;&quot; and &quot;NULL&quot; by NULL before jsonification.<br><br><=
/div><div>Pavel<br>=C2=A0<br></div><blockquote class=3D"gmail_quote" style=
=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=
=3D"ltr"><div><br></div><div>PS. It would be great to have a=C2=A0<span sty=
le=3D"font-family:monospace,monospace">json_strip_values (json, array) wher=
e array contains the list of values you want removed.=C2=A0</span></div></d=
iv>
</blockquote></div><br></div></div>

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