change a json field

[Vas K]

After a curl request on my server i get this response:

{ "_id":"b63",

"_rev":"1-15d",

"cmdText":"130104",

"ndNumber":9999,

"cmdCode":4,

"tmStamp":"2013-01-04 11:56:53",

"AnsText":";9999;04;No Data;" }

How can I change the field ndNumber and the field AnsText to something else(number and string) and then output the json into a string to send it back to the server?

I am already using json_loads to access the json and json_object_get to access the "ndNumber" and "AnsText" fields. 

[Petri Lehtinen]

You're almost there. Now you just create new values using
json_integer() and json_string(), and use json_object_set_new() to replace
the values in the original object:

json_object_set_new(obj, "ndNumber", json_integer(1234));
json_object_set_new(obj, "AnsText", json_string("foo bar"));

Then serialize the object using json_dumps() and send it back.

Petri

[Vas K]

thank you.I use json_object_set either for a new object or change the value of an old one.I hope its ok.

[Petri Lehtinen]

Vas K wrote:
> thank you.I use json_object_set either for a new object or change the value of
> an old one.I hope its ok.

Yes, it's OK.

[rogerz]

On Friday, April 26, 2013, Vas K wrote:

thank you.I use json_object_set either for a new object or change the value of an old one.I hope its ok.

I think you should be careful about memory leak when using json_object_set().

    json_object_set(obj, "ndNumber", json_integer(1234)); 

The extra ref to anonymous json_integer(1234) will keep it in memory when you do json_decref(obj).
    

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[vkefa...@gmail.com]

thanks for the advice. but i dont understand. how can i avoid the memory leak?

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[rogerz]

On Saturday, April 27, 2013, wrote:

thanks for the advice. but i dont understand. how can i avoid the memory leak?

use API with suffix "_new" for anonymous json_t so the reference won't be increased but borrowed from source, as in the example given by Petri.

json_object_set() is suitable for referencing existing json_t. Suppose you are extracting ns from response and use it in another obj.

// response = {nd: 1234, ns: "str"}

json_t *obj = json_object();

json_object_set(obj, "res_nd", json_object_get(response, "nd"));

json_decref(response);

json_decref(obj);

There's no auto garbage collection in C, so we should be really careful about the reference management in jansson.

I wonder if Petri has any good suggestion on it. I sometimes make mistake on it by myself.

Sent from my android device.

-----Original Message-----
From: rogerz <rogerz...@gmail.com>
To: "jansso...@googlegroups.com" <jansso...@googlegroups.com>
Sent: Sat, 27 Apr 2013 0:45
Subject: Re: [jansson-users] change a json field
 

On Friday, April 26, 2013, Vas K wrote:

thank you.I use json_object_set either for a new object or change the value of an old one.I hope its ok.

I think you should be careful about memory leak when using json_object_set().

    json_object_set(obj, "ndNumber", json_integer(1234)); 

The extra ref to anonymous json_integer(1234) will keep it in memory when you do json_decref(obj).

--
rogerz