Obviously Qt5 has better support for JSON. The Qt example http://doc.qt.io/qt-5/qtcore-json-savegame-example.html explains how to parse and also modify JSON files or object, which is great.
But for my requirement I should create a completely new JSON file, so I can't use the methods to modify existing JSON parameters. Maybe I didn't understand the examples, but how can I create a completely new JSON object?
thanks!
Should be rather straight forward:
QJsonObject myJsonObj;
myJsonObj["MyValue"] = 10;
QJsonDocument doc(myJsonObj);
QFile file("MyFile.json");
file.open(QIODevice::WriteOnly | QIODevice::Text);
file.write(doc.toJson(QJsonDocument::Indented));
Related
I am new to spring batch and there is a requirement for me to read the data from DB and write in to JSON format. whats the best way to do this ? Any api's are there? or we need to write custom writer ? or i need to user JSON libraries such as GSON or JACKSON ? Please guide me...
To read data from a relational database, you can use one of the database readers. You can find an example in the spring-batch-samples repository.
To write JSON data, Spring Batch 4.1.0.RC1 provides the JsonFileItemWriter that allows you to write JSON data to a file. It collaborates with a JsonObjectMarshaller to marshal an object to JSON format. Spring Batch provides support for both Gson and Jackson libraries (you need to have the one you want to use in the classpath). You can find more details here.
Hope this helps.
You do not need GSON or Jackson Libraries if you DB support JSON.
Example : In SQL Server there is an option to get data out of DB as JSON String instead of resultset.
Reference - https://learn.microsoft.com/en-us/sql/relational-databases/json/format-query-results-as-json-with-for-json-sql-server?view=sql-server-2017
https://learn.microsoft.com/en-us/sql/relational-databases/json/format-nested-json-output-with-path-mode-sql-server?view=sql-server-2017
Example - select (select * from tableName for json path) as jsonString;
This will already give you output in JsonString which you can write to a file.
I am having trouble saving a JSONObject to a MongoDB database using the MongoDB plugin.
I receive the message:
Can't find a codec for class org.codehaus.groovy.grails.web.json.JSONObject..
This is very frustrating because I am using the JSON parser to load JSON data but can't persist this JSON data to the MongoDb which should be straightforward.
Is there a built in way to convert a JSONOBject to a normal Map? I've tried casting it using asType( Map ), ( Map ), and even using toString() and thent rying to convert back from string to object. I've seen that other vanilla Java questions involve using Jackson but I'm hoping there is a Groovier way to do this rather than importing a whole new library for just two lines of code.
This is what I'm doing for now:
Converting the JSONObject to a string and then using com.mongodb.util.JSON.parse() to convert that string to a DBObject that Mongo can use.
It's not the best but it works for now.
I'm not going to accept this answer because I don't think it's the right answer.
Not saying this is the correct answer, but I was able to convert the JSONObject to a HashMap. For my situation I had a Domain object with an ArrayList (converted from JSONArray by a previous JSONTranslationService) and I was able to convert each of the internal JSONObjects using something like this:
static final UNMARSHAL = { thing ->
thing.objects.collect {
it as Hashmap
}
}
I'm only experiencing this issue after an upgrade from mongodb:3.0.2 to 6.1.2 to support MongoDB 3.4. Are you also running this version of the plugin? If so, I think it's fair to say that there's either a bug in the plugin (I'm already aware of one) or something changed with the default behavior and wasn't documented.
I need suggestion for my requirement of writting the QString data to json format.
Im reading data from dbus which returns me data in QString and QVariantMap and im using the data for my Qt GUI.
at the same time i have to feed the data to a web application .
the web application developer asked me to give the data in JSON format so he can read and write the data in his application .
so can you people suggest me a good way of writtin the data which comes from DBUS every time from DBUS to the JSON format .
Please provide me if any alternate solution or how i can synchronously write a JSON file .
A JSON object is quite similar to a map. If you're using Qt 5 writing data to JSON objects is very easy:
// String you would like to send to the web application
QString myString("Hi there!");
// JSON object used to store the data to be sent to the web application
QJsonObject myObject;
myObject.insert("key used by the web application", myString);
QJsonDocument myDocument(myObject);
At this point you can use myDocument to obtain the JSON representation of your data, by means of toJson() method. As an example:
qDebug() << myDocument.toJson();
produces this output:
{
"key used by the web application": "Hi there!"
}
Have a look at this link. It adds the support for JSON format in QT if you are using Qt 5.
I have not used it yet, but might be helpful.
The example of using the JSON with Qt can be found in this example.
I am loading data from a mongodb collection to a mysql table through Kettle transformation.
First I extract them using MongodbInput and then I use json input step.
But since json input step has very low performance, I wanted to replace it with a
javacript script.
I am a beginner in Javascript and even though i tried somethings, the kettle javascript script is not recognizing any keywords.
can anyone give me sample code to convert Json data to different columns using javascript?
To solve your problem you need to see three aspects:
Reading from MongoDB
Reading from JSON
Reading from (probably) String
Reading from MongoDB Except if you changed the interface, MongoDB returns not JSON but BSON files (~binary JSON). You need to see the MongoDB documentation about reading and writing BSON: probably something like BSON.to() and BSON.from() but I don't know it by heart.
Reading from JSON Once you have your BSON in JSON format, you can read it using JSON.stringify() which returns a String.
Reading from (probably) String If you want to use the capabilities of JSON (why else would you use JSON?), you also want to use JSON.parse() which returns a JSON object.
My experience is that to send a JSON object from one step to the other, using a String is not a bad idea, i.e. at the end of a JavaScript step, you write your JSON object to a String and at the beginning of the next JavaScript step (can be further down the stream) you parse it back to JSON to work with it.
I hope this answers your question.
PS: writing JavaScript steps requires you to learn JavaScript. You don't have to be a master, but the basics are required. There is no way around it.
you could use the json input step to get the values of this json and put in common rows
In AS3, I want lo load a file text with URLLoader. In the file text I have the following string:
{a:1,b:"string",c:["one","two"]}
Is it possible (once loaded) to convert it to an Object?
There is no intrinsic deserializer built into the language, no. But if your text file sticks to the JSON standard, then you could use a JSON parser to do the conversion for you: http://code.google.com/p/as3corelib/source/browse/#svn%2Ftrunk%2Fsrc%2Fcom%2Fadobe%2Fserialization%2Fjson
Or, if you cannot adhere to JSON, you could always write your own deserializer.
What you need is to eval the string to create the object.
This is done natively in javascript and AS2. AS3 however does not support this function.
But all is not lost. The people at Hurlant have created a library that does this "almost" as good as native JavaScript.
Here is a good example.
And another library example using d.eval
I would like to point out though that if you have accept to the source of the object string that you create a JSON object out of it. The JSON libraries are usually much easier and more reliable to use then the libraries that do Eval.
Your string is a sting with JSON format. Use JSONDecoder to decode it to an Object, like this:
var dc:JSONDecoder = new JSONDecoder("{a:1,b:'string',c:['one','two']}");
var ob:Object = dc.getValue();