Is there a way to convert string to json in Ballerina ?
I found this PR - Add jsons:parse() method to get a JSON from a string where it says adding support to parse string to json, but couldn't find any example.
I tried the following:
string person = {"name":"John", "address":{"number":89, "street":"main street", "town": "Colombo"}};
json personJson = sons:parse(person);
But it gave me an error:
undefined package 'jsons'
undefined function 'parse'
The correct way to convert a string to json in ballerina is to use the readJson function from StringReader. What you have tried was an old approach which is no longer supported.
Following example shows how this could be done using the StringReader.
import ballerina/io;
public function main(string... args) {
string str = "{\"name\":\"John\", \"address\":{\"number\":89, \"street\":\"main street\", \"town\":\"Colombo\"}}";
io:StringReader sr = new(str, encoding = "UTF-8");
json j = check sr.readJson();
io:println(j);
}
More info about StringReader can be found from the docs at - https://ballerina.io/learn/api-docs/ballerina/io.html#StringReader
From Ballerina swan lake onward, you can use the fromJsonString() method to convert a string to json:
string jsonStr = "{\"key\": \"value\"}";
json|error converted = jsonStr.fromJsonString();
if (converted is error) {
io:println("Error in parsing json");
} else {
io:println(converted);
}
Related
I have a server set up to send messages over a local host port. I am trying to decode the serialized json messages sent by the server and get this error.
Error decoding message: kotlinx.serialization.json.internal.JsonDecodingException: Unexpected JSON token at offset 55: Expected EOF after parsing, but had instead at path: $
JSON input: .....mber":13,"Timestamp":5769784} .....
The Racer State messages are formatted in JSON as follows: { “SensorId”: “value”, “RacerBibNumber” : “value”, “Timestamp” : “value” }, where the value’s are character string representations of the field values. I have also tried changing my RacerStatus Class to take String instead of Int but to a similar error. Am I missing something here? The symbol that is missing in the error was not able to be copied over so I know it's not UTF-8.
I have also added
val inputString = bytes.toString(Charsets.UTF_8)
println("Received input: $inputString")
This gets
Received input: {"SensorId":0,"RacerBibNumber":5254,"Timestamp":3000203}
with a bunch of extraneous symbols at the end.
data class RacerStatus(
var SensorId: Int,
var RacerBibNumber: Int,
var Timestamp: Int
) {
fun encode(): ByteArray {
return Json.encodeToString(serializer(), this).toByteArray()
}
companion object {
fun decode(bytes: ByteArray): RacerStatus {
print(bytes[0])
try {
val mstream = ByteArrayInputStream(bytes)
return Json.decodeFromStream<RacerStatus>(mstream)
} catch (e: SerializationException) {
println("Error decoding message: $e")
return RacerStatus(0, 0, 0)
}
// return Json.decodeFromString(serializer(), mstream.readBytes().toString())
}
}
}
So I found an answer to my question. I added a regex to include just the json components I know my json contains.
val str = bytes.toString(Charsets.UTF_8)
val re = Regex("[^A-Za-z0-9{}:,\"\"]")
return Json.decodeFromString<RacerStatus>(re.replace(str,""))
I thought that Charsets.UTF_8 would remove the misc characters but it did not. Is there a more intiuative solution? Also is there a regex that would cover all possible values in json?
I have JSON as a string and a JSONPath as a string. I'd like to query the JSON with the JSON path, getting the resulting JSON as a string.
I gather that Jayway's json-path is the standard. The online API, however, doesn't have have much relation to the actual library you get from Maven. GrepCode's version roughly matches up though.
It seems like I ought to be able to do:
String originalJson; //these are initialized to actual data
String jsonPath;
String queriedJson = JsonPath.<String>read(originalJson, jsonPath);
The problem is that read returns whatever it feels most appropriate based on what the JSONPath actually finds (e.g. a List<Object>, String, double, etc.), thus my code throws an exception for certain queries. It seems pretty reasonable to assume that there'd be some way to query JSON and get JSON back; any suggestions?
Java JsonPath API found at jayway JsonPath might have changed a little since all the above answers/comments. Documentation too. Just follow the above link and read that README.md, it contains some very clear usage documentation IMO.
Basically, as of current latest version 2.2.0 of the library, there are a few different ways of achieving what's been requested here, such as:
Pattern:
--------
String json = "{...your JSON here...}";
String jsonPathExpression = "$...your jsonPath expression here...";
J requestedClass = JsonPath.parse(json).read(jsonPathExpression, YouRequestedClass.class);
Example:
--------
// For better readability: {"store": { "books": [ {"author": "Stephen King", "title": "IT"}, {"author": "Agatha Christie", "title": "The ABC Murders"} ] } }
String json = "{\"store\": { \"books\": [ {\"author\": \"Stephen King\", \"title\": \"IT\"}, {\"author\": \"Agatha Christie\", \"title\": \"The ABC Murders\"} ] } }";
String jsonPathExpression = "$.store.books[?(#.title=='IT')]";
JsonNode jsonNode = JsonPath.parse(json).read(jsonPathExpression, JsonNode.class);
And for reference, calling 'JsonPath.parse(..)' will return an object of class 'JsonContent' implementing some interfaces such as 'ReadContext', which contains several different 'read(..)' operations, such as the one demonstrated above:
/**
* Reads the given path from this context
*
* #param path path to apply
* #param type expected return type (will try to map)
* #param <T>
* #return result
*/
<T> T read(JsonPath path, Class<T> type);
Hope this help anyone.
There definitely exists a way to query Json and get Json back using JsonPath.
See example below:
String jsonString = "{\"delivery_codes\": [{\"postal_code\": {\"district\": \"Ghaziabad\", \"pin\": 201001, \"pre_paid\": \"Y\", \"cash\": \"Y\", \"pickup\": \"Y\", \"repl\": \"N\", \"cod\": \"Y\", \"is_oda\": \"N\", \"sort_code\": \"GB\", \"state_code\": \"UP\"}}]}";
String jsonExp = "$.delivery_codes";
JsonNode pincodes = JsonPath.read(jsonExp, jsonString, JsonNode.class);
System.out.println("pincodesJson : "+pincodes);
The output of the above will be inner Json.
[{"postal_code":{"district":"Ghaziabad","pin":201001,"pre_paid":"Y","cash":"Y","pickup":"Y","repl":"N","cod":"Y","is_oda":"N","sort_code":"GB","state_code":"UP"}}]
Now each individual name/value pairs can be parsed by iterating the List (JsonNode) we got above.
for(int i = 0; i< pincodes.size();i++){
JsonNode node = pincodes.get(i);
String pin = JsonPath.read("$.postal_code.pin", node, String.class);
String district = JsonPath.read("$.postal_code.district", node, String.class);
System.out.println("pin :: " + pin + " district :: " + district );
}
The output will be:
pin :: 201001 district :: Ghaziabad
Depending upon the Json you are trying to parse, you can decide whether to fetch a List or just a single String/Long value.
Hope it helps in solving your problem.
For those of you wondering why some of these years-old answers aren't working, you can learn a lot from the test cases.
As of September 2018, here's how you can get Jackson JsonNode results:
Configuration jacksonConfig = Configuration.builder()
.mappingProvider( new JacksonMappingProvider() )
.jsonProvider( new JacksonJsonProvider() )
.build();
JsonNode node = JsonPath.using( jacksonConfig ).parse(jsonString);
//If you have a json object already no need to initiate the jsonObject
JSONObject jsonObject = new JSONObject();
String jsonString = jsonObject.toString();
String path = "$.rootObject.childObject"
//Only returning the child object
JSONObject j = JsonPath.read(jsonString, path);
//Returning the array of string type from the child object. E.g
//{"root": "child":[x, y, z]}
List<String> values = sonPath.read(jsonString, path);
Check out the jpath API. It's xpath equivalent for JSON Data. You can read data by providing the jpath which will traverse the JSON data and return the requested value.
This Java class is the implementation as well as it has example codes on how to call the APIs.
https://github.com/satyapaul/jpath/blob/master/JSONDataReader.java
Readme -
https://github.com/satyapaul/jpath/blob/master/README.md
I want to use the following JSON in my code in Java:
[
{
"speed": 200
}
]
I tried to write this line :
JSONObject jsonBody = new JSONObject("[{\"speed\": 200}]");
But I always get an error. What is the exact format that I have to use here??
EDIT: So it would be more proper to use a JSONArray rather than use a JSONObject (as my last post said)
So the correct java code would be
String json = "[{\"speed\": 200}]";
System.out.println(json);
JSONArray jsonBody = new JSONArray(json);
System.out.println(jsonBody.getJSONObject(0).get("speed"));
I am trying to receive a JSON string in salesforce by converting a blob in the body of an Http request. However, when I convert the blob to a string there are \ characters that get inserted into the request which prevents me from parsing.
I then tried to take the string and remove all \ characters... that didn't work either.
RestRequest req = RestContext.request;
Blob jsonBlob = req.requestBody;
String jsonString = jsonBlob.toString();
return jsonString;
The original string (the one that is received as a blob) looks like this:
{"putTimeCard":{"timecard":{"timeCardID": "","employeeID": ""}}
And after converting to a salesforce string and assigned to the jsonString is altered to:
{\"putTimeCard\":{\"timecard\":{\"timeCardID\": \"\",\"employeeID\": \"\"}}
Has anyone found a solution for this?
Thanks
The JSON Deserializer can parse the string with the escape characters. You can either deserialize into an object like so:
String jsonString = '{\"putTimeCard\":{\"timecard\":{\"timeCardID\": \"\",\"employeeID\": \"\"}}}'
Timecard t = (Timecard) JSON.deserialize(jsonString, Type.forName('Timecard'));
or if you just want a map of objects you can do the following:
String jsonString = '{\"putTimeCard\":{\"timecard\":{\"timeCardID\": \"\",\"employeeID\": \"\"}}}'
Map<String, Object> m = (Map<String, Object>) JSON.deserializeUntyped(jsonString);
My JSON string looks like this. Please note that it has escape characters.
string json = "\"{\\\"Status\\\":true,\\\"ID\\\":24501}\"";
When I use the Parse method like below I run into an error stated below:
JObject o = JObject.Parse(json);
Error reading JObject from JsonReader. Current JsonReader item is not an object: String
How do I get rid of this error or is there any other method to parse my json string and fetch the values?
Remove first and last quotes:
string json = "{\"Status\":true,\"ID\":24501}";
See the Json format here.
It seems like your object is double encoded. Try:
string json = "{\"Status\":true,\"ID\":24501}";
You need something like this
json = json.Replace(#"\", string.Empty).Trim(new char[]{'\"'})
in here format should be something like this:
string jsonNew = #"{'Status': True,'ID': 24501 }";
As SolarBear says in his comment, the problem is double-escaping.
To get the proper format, like this:
string json = "{\"Status\":true,\"ID\":24501}";
Do something like this:
json = json.Replace("\\\\", "\\");
Had similar issue today. My solution to this is contained in this extension method (using c#):
public static class StringExtensions
{
public static string RemoveDoubleEncoding(this string text)
{
if(string.IsNullOrEmpty(text))
return string.Empty;
var result = text.TrimStart('\"').TrimEnd('\"');
result = result.Replace(#"\", string.Empty);
return result;
}
}