Develop Reference

Accesing only key names of json using jsonPath

I have a simple question, say I have the following json
{
"ALPHA":[
....
],
"BETA":[
....
],
"GAMMA":[
.....
]
}
how do I access the subroot elements, I mean just the names: "ALPHA","BETA","GAMMA" using jsonPath? Be aware that I mean their names not their array!!!
I tried jsonPath("$[*]", ...) but it doesn't work, any sugesstions?

You may consider another library Josson. Just one function keys() can do the job.
https://github.com/octomix/josson
Josson josson = Josson.fromJsonString(
"{" +
" \"ALPHA\":[" +
" 1,2,3,4" +
" ]," +
" \"BETA\":[" +
" 5,6,7" +
" ]," +
" \"GAMMA\":[" +
" 8,9" +
" ]" +
"}");
JsonNode node = josson.getNode("keys()");
System.out.println(node.toPrettyString());
Output
[ "ALPHA", "BETA", "GAMMA" ]

Thanks a lot #Raymond Choi, it should also work.
But based on your answer, that I should use the function keys(), I search a lit bit more and I found that jsonPath indeed has his own function.
So the solution to my question is simple:
jsonPath("$.keys())

Insert Kotlins ${ } expression while splitting String() in order to add dynamic data after the split

Here is an example of a String:
val message = "Customer name is $name saved on $date"
I needed to find every instance of $variable within the string message and replace it with querySnapShot.get(variable) and that has been answered here Previous Answer. querySnapShot here just contains data from within Firestore listener.
Here is the working Kotlin code:
val message = "Customer name is $name saved on $date"
val arr = message.split(" ").toTypedArray()
for (i in 0 until arr.size) {
val s = arr[i]
if (s.contains("$")) {
arr[i] = "+ querySnapshot.get(" + "\"" + s.substring(1) + "\"" + ")"
}
}
Log.d("Mate", java.lang.String.join(" ", *arr))
which prints:
customer name is querySnapShot.get("name") saved on querySnapshot.get("data)
literally as it is.
QUESTION:
How can I add Kotlin's expression ${} correctly while splitting and joining in order for it to treat querySnapshot.get("variable") as an expression that captures and returns dynamic data after joining? And not just a mere String.

Write
arr[i] = querySnapshot.get(s.substring(1))
The solution isn't to try to use Kotlin string templating, it's to stop putting your own code in strings when you want to run it instead!

Gson 'fromJson' issue

I am trying to bind JSON to Java POJO class using com.google.gson.Gson
like this :
MyClass data = gson.fromJson(jsonString, MyClass.class);
When I am using below mentioned it's working fine
{
"data": "{\"key1\":{\"key11\":\"192.192.1.192\",\"key12\":\"WEB\"}}"
}
However, when below-mentioned data is used, I am getting MalformedJsonException
{
"data": "{"key1":{"key11":"192.168.1.158","key12":"WEB"}}"
}
Log :
com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException:
Unterminated object at line 1 column 354 path

You can not use " within a String to quote your JSON keys and values. You either have to escape them (like you did in your first example) or you have use single quotes '.
You are effectively trying to do String concatenation without using +.
This looks for the compiler like a list of Strings with variables in between:
"{"key1":{"key11":"192.168.1.158","key12":"WEB"}}"
The compiler would expect something like this:
"{" + key1 + ":{" + key11 + ":" + 192.168.1.158 + "," + key12 + ":" + WEB + "}}";
If you look at the String this way you immediately see the problem. That's why you should either escape the quotes or use single quotes:
"{\"key1\":{\"key11\":\"192.168.1.158\",\"key12\":\"WEB\"}}"
"{'key1':{'key11':'192.168.1.158','key12':'WEB'}}"

Error with Jongo parsing JSON

I'm using a combination of Java Play Framework, MongoDB and Jongo as my go between for a basic web CRUD app. I keep receiving a JSON parse exception even though my string doesn't contain any illegal characters. It's actually failing on closing curly bracket at the end of the statement. Below is my error and code. The query string is just a string builder, searching if an object is empty or has a value, if it has a value it's appended to a string.
Jongo method:
public static Iterable<OneDomain> findWithQueryString(String queryString){
return domains().find("{#}", queryString).as(OneDomain.class);
}
Controller Methods:
String builder example:
if(queryStringBuilder.toString().equalsIgnoreCase("")){
queryStringBuilder.append("date: {$gte : " + searchObj.dateFrom + ", $lt: " + searchObj.dateTo + "}");
}else{
queryStringBuilder.append(" , ");
queryStringBuilder.append("date: {$gte : " + searchObj.dateFrom + ", $lt: " + searchObj.dateTo + "}");
}
String queryString = queryStringBuilder.toString();
Iterable<OneDomain> filteredIterable = OneDomain.findWithQueryString(queryString);
Gives me this error:
Caused by: com.mongodb.util.JSONParseException:
{"source : Online Lists , blacklist : true , vetted : true , is : false , isNot : true"}
^
with the error on the "}" ending it.
In addition to that, if I try to escape the characters by putting in a \" so it becomes \"date\" it will parse and error out like so:
Caused by: com.mongodb.util.JSONParseException:
{"\"source\" : \"Online Lists\" , \"blacklist\" : true , \"vetted\" : true , \"is\" : false , \"isNot\" : true"}

You're building JSON by hand, and doing it wrong. You need to learn the basic JSON syntax requirements
A basic JSON-encoded object is
{"key1":"value1","key2":"value with \" escaped internal quote"}
Note all of the quotes. Your json string is a single very long object key with no associated value, which is not permitted. All keys must have values.

Adding a " to a string in code

I'm writing some code for web services for my Android app which uses JSON. The url should look like this
url = url + "?maddr=" + mailAddr + "&pwd=FB&lect=" + """ + lectName + """ + "&fb=Test";
This is because the Lectname may be two or more words. However the compiler wont accept """, is there a character I can precede the " with to get the compiler to accept it into my string?

Try " \" ". You have to escape the "
http://en.wikipedia.org/wiki/Escape_character
You need this in (nearly) every programming language.