In the Current code i'm using json-c. i'm migrating to jansson.
need an equivalent api in jansson which converts the json_object_to_json_string.
i found one but it needs a json string object otherwise it is returning null.
const char *json_string_value(const json_t *string) - not working
but my input is a JSON object not a JSON string
sample:
json_object *jobj = json_object_new_object();
....
const char *final_string = json_object_to_json_string(jobj);
Thanks.
I was in your position just recently, I believe the function you are looking for is:
char *json_dumps(const json_t *json, size_t flags)
Returns the JSON representation of json as a string, or NULL on error. flags is described above. The return value must be freed by the caller using free().
https://jansson.readthedocs.io/en/2.8/apiref.html#c.json_dumps
Related
Is it possible, with Ada, to implement the following JSON containing a function declaration x: integer (float(x))?
Example_JSON = "Integer": lambda x: integer (float(x))}
If so, how?
I've tried to find a method in GNATCOLL.JSON without success.
It is impossible because a JSON value, according to RFC 8259 can only be one of the following:
null
true
false
object
array
number
string
You can put the function's source code into a string, and then parse that string at the receiving end, e.g. {"integer": "lambda x: integer(float(x))"}, but there's no direct way for a function to be a value in an object.
I'm calling an API from Go and trying to push json string data from another api call into it.
I can hand craft the calls using a payload like
payload := strings.NewReader('[{"value1":333, "value2":444}]'
and everything is happy.
I'm now trying to covert this to take the json string {"value1":333, "value2":444} as an input parameter of type string to a function, but when I try and use that as the payload, the api is responding with
expected type: JSONArray, found: JSONObject
I naively tried setting the input to the function as []string and appending the data to an array as the input, but then strings.NewReader complained that it was being fed an array.. which is was.
I'm at a loss to work out how to convert a string of json into a json array that the api will be happy with.
I tried just surrounding the string with [] but the compiler threw a fit about incorrect line termination.
Must have been doing something wrong with the string, surrounding the {} with [] let the function pass the data, but there must be a better way than this.
Any ideas, or am I making this harder than it should be?
You were on the right track with the brackets, but you actually need to append the characters to the string. For example:
str := `{"value1":333, "value2":444}`
str = "[" + str + "]"
// [{"value1":333, "value2":444}]
https://play.golang.org/p/rWHCLDCAngd
If you use brackets outside a string or rune literal, then it is parsed as Go language syntax.
I'm using Flink to process the data coming from some data source (such as Kafka, Pravega etc).
In my case, the data source is Pravega, which provided me a flink connector.
My data source is sending me some JSON data as below:
{"key": "value"}
{"key": "value2"}
{"key": "value3"}
...
...
Here is my piece of code:
PravegaDeserializationSchema<ObjectNode> adapter = new PravegaDeserializationSchema<>(ObjectNode.class, new JavaSerializer<>());
FlinkPravegaReader<ObjectNode> source = FlinkPravegaReader.<ObjectNode>builder()
.withPravegaConfig(pravegaConfig)
.forStream(stream)
.withDeserializationSchema(adapter)
.build();
final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
DataStream<ObjectNode> dataStream = env.addSource(source).name("Pravega Stream");
dataStream.map(new MapFunction<ObjectNode, String>() {
#Override
public String map(ObjectNode node) throws Exception {
return node.toString();
}
})
.keyBy("word") // ERROR
.timeWindow(Time.seconds(10))
.sum("count");
As you see, I used the FlinkPravegaReader and a proper deserializer to get the JSON stream coming from Pravega.
Then I try to transform the JSON data into a String, KeyBy them and count them.
However, I get an error:
The program finished with the following exception:
Field expression must be equal to '*' or '_' for non-composite types.
org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:342)
org.apache.flink.streaming.api.datastream.DataStream.keyBy(DataStream.java:340)
myflink.StreamingJob.main(StreamingJob.java:114)
It seems that KeyBy threw this exception.
Well, I'm not a Flink expert so I don't know why. I've read the source code of the official example WordCount. In that example, there is a custtom splitter, which is used to split the String data into words.
So I'm thinking if I need to use some kind of splitter in this case too? If so, what kind of splitter should I use? Can you show me an example? If not, why did I get such an error and how to solve it?
I guess you have read the document about how to specify keys
Specify keys
The example codes use keyby("word") because word is a field of POJO type WC.
// some ordinary POJO (Plain old Java Object)
public class WC {
public String word;
public int count;
}
DataStream<WC> words = // [...]
DataStream<WC> wordCounts = words.keyBy("word").window(/*window specification*/);
In your case, you put a map operator before keyBy, and the output of this map operator is a string. So there is obviously no word field in your case. If you actually want to group this string stream, you need to write it like this .keyBy(String::toString)
Or you can even implement a customized keySelector to generate your own key.
Customized Key Selector
I'm using Firebase 32 Client (https://github.com/mobizt/Firebase-ESP32 ) in my project. I'm not able to use a character array in json.set function. I need to send the character array of 7 bytes ( made of numbers) to RTDB as json . Please guide me for the same.
You can use the String class to create String object from char array like this.
String myString = String(myCharArray);
Use this string with the FirebaseJson function in the Firebase library.
I am working on a WP8 app. In this I need to connect to web services whose results will be some JSON. I was trying to extract some data from the result that the web service provide. I was able to extract from the initial JSON response. But I need to get some data from the value of one such key . SO I tried to generate another Json object from it. But I m stuck. please help.Please find my example code below(I am using Newtonsoft.JSon).
private void messages_buttons_Click(object sender, RoutedEventArgs e)
{
var str = "{'status': '0', 'result': '%7B%22campaign_id%22%3A%221%22%2C%22tfn%22%3A%2218773374136%22%2C%22campaign_code%22%3A%22PJC%22%2C%22ad_id%22%3A%221%22%2C%22qr_url%22%3A%22http%3A%5C%2F%5C%2F1d1.us%5C%2FPJC%5C%2F%22%2C%22campaign_name%22%3A%22PJ+Test+Campaign%22%2C%22is_active%22%3A%221%22%2C%22expire_on%22%3A%222021-05-05+00%3A00%3A00%22%2C%22start_on%22%3A%222021-05-05+00%3A00%3A00%22%2C%22alias%22%3A%22%22%2C%22icon_image_url%22%3A%22products%5C%2Fpjc%5C%2Fpjc3.jpg%22%2C%22fb_page_url%22%3A%22https%3A%5C%2F%5C%2Fwww.facebook.com%5C%2FJackLaLannePowerJuicerssfb%22%2C%22video_url%22%3A%22http%3A%5C%2F%5C%2Fyoutube.com%5C%2Fembed%5C%2FyZPedpRA9r0%3Fshowinfo%3D0%26autoplay%3D1%26loop%3D1%26playlist%3DyZPedpRA9r0%22%2C%22url%22%3A%22https%3A%5C%2F%5C%2Fwww.facebook.com'}";
JObject ne = JObject.Parse(str);
var x= (ne.GetValue("result")).ToString();
var z = x.Replace("%", "");
JObject newest = JObject.Parse(z);
var y = newest.GetValue("campaign_id");
MessageBox.Show(y.ToString());
}
I get an exception at "JObject newest = JObject.Parse(z);" with the message
Unexpected character encountered while parsing number: m. Path '', line 1, position 6.
Am I doing it entirely wrong?
On a general note: can I convert a value from one Json to a another JSOn Itself? i.e if the value of one json key is a string with some key value pairs, can i make a json object on that string?
You can't actually just remove the % chars to get a valid value. You need to decode the string.
If you use this:
HttpUtility.UrlDecode(x);
You'll find your "result" is actually invalid JSON:
{"campaign_id":"1","tfn":"18773374136","campaign_code":"PJC","ad_id":"1","qr_url":"http://1d1.us/PJC/","campaign_name":"PJ
Test Campaign","is_active":"1","expire_on":"2021-05-05
00:00:00","start_on":"2021-05-05
00:00:00","alias":"","icon_image_url":"products/pjc/pjc3.jpg","fb_page_url":"https://www.facebook.com/JackLaLannePowerJuicerssfb","video_url":"http://youtube.com/embed/yZPedpRA9r0?showinfo=0&autoplay=1&loop=1&playlist=yZPedpRA9r0","url":"https://www.facebook.com
So hacking the value to make it valid JSON might work for you, by adding the missing "} at the end should turn your value in to valid JSON and allow you to parse it.
JObject newest = JObject.Parse(x + "\"}");
var y = newest.GetValue("campaign_id");
It doesn't appear that z is a valid json object at this point. It is only the value of result. Try something like JObject.Parse("'result':" + z);