reading a json object in jsp - javascript

i have a JSON object passed to the jsp page. it is passed as a string. now i have to parse this string and retrieve the values that are passed through the JSON object. so that i can print the values in the same jsp.


There's lots of resources, including libraries & plugins for various technologies/frameworks on json.org.


With tons of JSON parsers, it comes down to how you want to deal with data in JSON. My personal favorite from the lot is Jackson, but many others work well for simple cases too, including the "reference implementation" (aka JSON.org parser).
(I assume you want a Java parser, given reference to jsp)


My preferred solution to this problem involves using a JSON parser that provides an output that implements the java.util.Map and java.util.List interface. This allows for simple parsing of the JSON structure in the JSP Expression language.
Here is an example using JSON4J provided with Apache Wink. The sample imports JSON data from a URL, parses it in a java scriptlet and browses the resulting structure.
<c:import var="dataJson" url="http://localhost/request.json"/>
<%
String json = (String)pageContext.getAttribute("dataJson");
pageContext.setAttribute("parsedJSON", org.apache.commons.json.JSON.parse(json));
%>
Fetch the name of the node at index 1 : ${parsedJSON.node[1].name}
To make this clean, it would be preferable to create a JSTL tag to do the parsing and avoid java scriplet.
<c:import var="dataJson" url="http://localhost/request.json"/>
<json:parse json="${dataJson}" var="parsedJSON" />
Fetch the name of the node at index 1 : ${parsedJSON.node[1].name}

Related

marklogic javascript json does json documents have a namespace

I am trying to grasp the javascript and JSON documents in marklogic.
Does the JSON documents support namespaces and how do you implement one: that is add your own content. can some provide a simple example.

The JSON standard doesn't have namespaces.
Some people argue for ignoring properties that aren't recognized and for wrapping or renaming as needed to avoid naming collisions when composing a JSON document from multiple inputs.
Hoping that helps,

JSON file parsing issue due to javascript variables

I've been provided with a json file to show results in a tableview.
But when I tried json file validation using online json file editor then I am getting "Build tree failed" error.
I posted this message to my client about wrong json file and then he has posted some strange description which I am totally unaware.
Yes the json is not a pure json. It has javascript variables which have json variable. For now u can use a webview to evaluate the javascript variables and use the json value. For ex : dp_f : corresponds to list of departure train is a javascript array variable. U may have to eval the variable and store each array element is a new json with key as dp_f and value of array of these values
Please tell me how can I use this json file which is not pure. What is the way to parse such files ?

The only real way to evaluate JavaScript (which is really what you have, not JSON) is to evaluate JavaScript.
You will have to use some form of eval(). I recommend trying a JavaScript sandbox, if available to you. Of course the best option would be to get the data fixed.

Flash Twitter API with JSON

I have read a lot about parsing JSON with Actionscript. Originally it was said to use this library. http://code.google.com/p/as3corelib/ but it seems Flash Player 11 has native support for it now.
My problem is that I cannot find examples or help that takes you from beginning to end of the process. Everything I have read seems to start in the middle. I have no real experience with JSON so this is a problem. I don't even know how to point ActionScript to the JSON file it needs to read.
I have a project with a tight deadline that requires me to read twitter through JSON. I need to get the three most recent tweets, along with the user who posted it, their twitter name and the time those tweets were posted.
The back end to this is already set up I believe by the development team here, therefor my JSON files or XML just needs to be pointed to and then I need to display the values in the interface text boxes I have already designed and created.
Any help will be greatly appreciated...I do know that there are a lot of threads on here I just do not understand them as they all have some understanding of it to begin with.

You need to:
Load the data, whatever it is.
Parse the data from a particular format.
For this you would normally:
Use URLLoader class to load any data. (Just go to the language reference and look into example of how to use this class).
Use whatever parser to parse the particular format that you need. http://help.adobe.com/en_US/FlashPlatform/beta/reference/actionscript/3/JSON.html this is the reference to JSON API, it also shows usage examples. I'm not aware of these API being in production version of the player, still there might be quite a bit of FP 10.X players out there, so I'd have a fallback JSON parser, but I would recommend using this library: http://www.blooddy.by/en/crypto/ over as3corelib because it is faster. The built-in API are no different from those you would find in browser, so if you look up JSON JavaScript entries, the use should be in general similar to Flash.
After you parse JSON format, you will end up with a number of objects of the following types: Object, Array, Boolean, Number, String. It has also literals to mean null and undefined. Basically, you will be working with native to Flash data structures, you only should take extra care because they will be dynamically constructed, meaning you may not make assumption about existence of parts of the data - you must always check the availability.

wvxvw's answer is good, but I think skips over a to be desired explanation of what JSON itself is. JSON is plain text, javascript object notation, when you read the text on screen it looks something like this
http://www.json.org/example.html
you can see a side by side JSON and XML (both plain text formats) essentially JSON is a bunch of name value pairs.
When you use JSON.parse("your JSON string goes here") it will do the conversions to AS3 "dynamic objects" which are just plain objects (whose properties can be assigned without previously being defined, hence dynamic). But to make a long story short, take the example you see in the link above, copy and paste the JSON as a string variable in AS3, use
var str:String = '{"glossary": {"title": "example glossary","GlossDiv": {"title": "S","GlossList": {"GlossEntry": {"ID": "SGML","SortAs": "SGML","GlossTerm": "Standard Generalized Markup Language","Acronym": "SGML","Abbrev": "ISO 8879:1986","GlossDef": {"para": "A meta-markup language, used to create markup languages such as DocBook.","GlossSeeAlso": ["GML", "XML"]},"GlossSee": "markup"}}}}}';
var test:Object = JSON.parse(str);
method on the string, store it in a variable and use the debugger to see what the resulting object is. As far as I know there's really nothing else to JSON it's simply this format for storing data (you can't use E4X on it since it's not XML based and because of that it's slightly more concise than XML, no closing tags, but in my opionion slightly less readable... but is valid javascript). For a nice break-down of the performance gains/losses between AMF, JSON and XML check out this page: http://www.jamesward.com/census2/ Though many times you don't have a choice with regard to the delivery message format or protocol being used if you're not building the service, it's good to understand what the performance costs of them are.

JSON to String on client side for ASP.NET Script Service?

From this site, I've learned that ASP.NET script services accepting JSON actually require them to be serialized JSON strings (see: "JSON, objects, and strings: oh my!" section of the link). Is there a quick and easy way to serialize them for ASP.NET AJAX consumption on the client side instead of trying to manually convert a bunch of existing objects to JSON-looking strings?
Thanks in advance!

You can use JSON.stringify() to serialize client-side objects for consumption in ASP.NET's Script Services.
Using that approach, you can map client-side objects to server-side objects very easily. ASP.NET will automatically handle converting the JSON to objects (or even collections of objects) for you.

The article writer is confusing Javascript objects with JSON strings. There is no such thing as a "JSON object".
Naturally if you try to send an object to a web service, it has to be serialised, as the request data can only contain text, not objects. The standard way of serialising data to be posted is URL encoding it, so that is what jQuery does.
There is no JSON serialisation built into Javascript or jQuery. You would have to do the serialising yourself or find a library that does it. Here are some options: Serializing to JSON in jQuery
Also, the data sent in the example is not valid JSON. It looks like this:
"{'fname':'dave', 'lname':'ward'}"
To be valid JSON it should look like this:
'{"fname":"dave", "lname":"ward"}'

Javascript library for exporting XML

I'm currently using couchdb to store documents as JSON. One of my clients needs to grab XML (for now). Anyone know any good javascript libraries that can take a javascript object (or json string) and export valid xml?
Thanks!

json2xml.js: http://goessner.net/download/prj/jsonxml/

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