Develop Reference

Can't parse JSON array of objects

I have a NodeJS cloud function that takes a bunch of javascript objects (entries from a db) in the form of an array, and sends them to the client.
On the server I do this using:
return JSON.stringify(result);
Where "result" is the array of JS objects. Then I send data to the client.
In my Android client, I receive the String, and need to iterate through every object in the original array and process them separately. I can't! I always get errors like:
I: [Batch] com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Expected name at line 1 column 3 path $[0].
On my Android client, I have tried:
WebItemEntry [] items = new Gson().fromJson(jsonString, WebItemEntry[].class);
AND ...
ArrayList<WebItemEntry> items = new Gson().fromJson(jsonString, new TypeToken<ArrayList<WebItemEntry>>(){}.getType());
Neither seem to work. Same error as above.
The raw output I get from the database is the JSON string that consists of five individual entries that I would like to iterate through and parse. Its kind of a mess, but you can see its deliminator is the brace {. I really want to use GSON or similar in my android client to parse these entries individually and convert them to my custom Java class: WebItemEntry.
[{\"charityID\":0,\"purchaserZIP\":\"\",\"category\":\"Women\u0027s Accessories\",\"valueCents\":0}, {... same thing for a different entry here...}, {new entry ... }]

On the server ignore stringify and return plain object, those \" characters appear when js object stringify twice. so replace return JSON.stringify(result); with return result;.

Proper json to back end post call

I'm having some troubles with different back-end processing of POST rest calls. I have two different objects which are updated through two different POST methods in my back-end. I catch the objects as a JsonNode, and in order to parse the attributes which I need to update, i create an iterator like so :
final Iterator<String> fieldNames = attributes.fieldNames();
The problem comes when I send my data from angular, in one case I need to explicitly send it like angular.toJson(data) in order to properly grab all the field names, and in the other case I just send the data (without the angular json conversion). Why is this behavior occurring ? Does this have to do with how I create the $http post call ? Here are the two different calls from angular:
$http.post(URL, angular.toJson(data)).success(function(data){
/*whatever*/ }).error(function(data) {
/*whatever*/ });
//Second call looks like this
var promise = $http({method: 'POST', url:URL, data:data, cache:'false'});
//this one i resolve using $q.all
I truncated the code to just the important stuff. My data is created like this currently(tried multiple ways in order to skip the need for toJson):
var data = "{\"Attribute1:\"+"\""+$scope.value1+"\","+
"\"Attribute2:\"+"\""+$scope.value2+"\"}";
How do I need to send the json data in order for it to correctly be converted to a JsonNode in my back-end, so I can properly iterate the fieldNames ?

I did manage to come to a common solution which consumes the json correctly in my back-end. I declared my json objects in angular like this :
$scope.dataToSend = {
"SomeAttribute" : "",
"SomeOtherAttribute" : ""
};
And then added my values like so :
$scope.dataTosend.SomeAttribute = someValue;
$scope.dataTosend.SomeOtherAttribute = someOtherValue;
No longer need to send the data with angular.toJson().

Sending a GET request through a REST API in Java with multiple inputs

I need to send a request using Java to an existing REST service using GET with multiple input parameters.
If the initial url for the calculation I want is:
https://api.restservice123.com/api/calculate
I want to make a calc object e with the following parameters:
calcObj e = new calcObj();
e.token="token_ABC123";
e.country="US";
e.amount = 100;
e.price = 24;
e.customer = "bob";
the url should look something like this:
https://api.restservice123.com/api/calculate?token=token_ABC123&country=US&amount=100&price=24&customer=bob
Is there any framework that will combine the parameters from the calc object and reformat them into the url appropirate format and combine them with the api url?
I ended up making a method in the calc object that puts all the non null parameters into a list of strings and combines them using a Joiner from google common and connecting to the url using an HttpURLConnection. But this method looks bad as I'm hoping there's something out there that can already do all of this much more elegantly, but I couldn't find it.

The URIBuilder class works well for this. It has a method setParameters(java.util.List) that takes a list of name value pairs and builds a URI from them.

creating array in javascript from array object pass in by request.setAttribute in servlet

i'm trying to create a dynamic photo gallery which retrieve the photo's location from mySQL. Store the location to a photo object under the name 'private String location;'
There will be an ArrayList to hold all the different photos. After, the servlet will forward to a jsp page
request.setAttribute("list", list);
request.getRequestDispatcher("car.jsp").forward(request, response);
i have a java script for the photo gallery that takes in an array of, ["path_to_image", "optional_link", "optional_linktarget", "optional_textdescription"].
imagearray: [
["path_to_image", "optional_link", "optional_linktarget", "optional_textdescription"],
["a.jpg", "www.a.com", "", ""]
],
I would like to retrieve the location from the object in the list passed in from the servlet and convert it into the imagearray for my photo gallery to work.
I'm quite new to javascript and i've been looking around for similar example or tutorial but i couldn't find any relevant ones. Please help me out, thank you so much for your time.

what i get from your question is photo is an object of a class and location is a member variable of that class.
request.setAttribute("list", list);
request.getRequestDispatcher("car.jsp").forward(request, response);
is this list is a Arraylist of photo object or location member variable.
also you are setting attribute in java and you want that list to hold by javascript.
then in that case you can check JSON for holding your java object and to convert into javascript object.
you will get your string in JSON similar to
{imagearray:[{"path_to_image":"path_to_image","optional_link":"optional_link","optional_linktarget":"optional_linktarget","optional_textdescription"}]}

What you want to do can be simply achieved by the following sequence:
Get results from a database.
Create JSON object.
Set that object as request attribute.
Assign JSON to a JavaScript variable.
Now, let's carry on doing that list.
Get results from database
You should have a method of type getPhotoList() that returns List<Photo>. I suppose that your Photo class has the fields you'd like to export to JavaScript. In the end, you'll have List<Photo> photos initialized.
Create a JSON object
You can of course do that on your own, but a much better idea is to employ a specialized library that converts a java object to a JSON object. For example, you could use Gson library, which is a known library for that type of conversions. In the end, you'll have a JSON object, by calling String photosJSON = new Gson().toJson(photos);.
Set the JSON as a request attribute and perform a forward
Standard operation here.
request.setAttribute("photos", photosJSON);
request.getRequestDispatcher("car.jsp").forward(request, response);
Assign JSON to a JavaScript variable
In your JSP code, within a <script> block, have the following line:
var photosJS = JSON.parse(${photos});
Finally, you'll have a JS variable photosJS with a list you got from the database.

Passing Jackjson JSON object from JSP to JavaScript function

I have a JSON String stored in a database. In one of my JSP pages, I retrieve this string, and I want to be able to pass the String or the JSON object into Javascript function. The function is simply this for test purposes
function test(h){
alert(h);
}
Now I can retrieve the JSON string from the database fine, I have printed it out to the screen to ensure that it is getting it, however when I pass it in like this
<input type="button"
name="setFontButton"
value="Set"
class="form_btn_primary"
onclick="test('<%=theJSON%>'); return false;"/>
Nothing happens. I used firebug to check what was wrong, and it says there is invalid character.
So I then tried passing in the JSON object like so
Widget widg = mapper.readValue(testing.get(0), Widget.class);
Then pass in it
onclick="test('<%=widg%>'); return false;"/>
Now this will pass in without an error, and it alerts the object name, however I am unable to parse it. Object comes in like with the package name of where the widget class is stored like so
com.package.mode.Widget#ba8af9
I tried using Stringify, but that doesn't seem to work on this Jackson JSON object.
After all that failed, I tried a last resort of taking the String from the database, and encoding it in base64. However, this too fails if I do this
String test = Base64.encode(theString);
and pass that in. However if I do that, print it out to the screen, then copy what is printed out, and send that through it works, so don't quite understand why that is.
So could someone please tell me what I am doing wrong. I have tried soo many different solutions and nothing is working.
The JSON String is stored in database like this
{
"id":1,
"splits":[
{
"texts":[
{
"value":"Test",
"locationX":3,
"locationY":-153,
"font":{
"type":"Normal",
"size":"Medium",
"bold":false,
"colour":"5a5a5a",
"italics":false
}
}
]
}
]
}
Would be very grateful if someone could point me in the direct direction!!
Edit:
Incase anyone else has same problem do this to pass the JSON from JSP to the JS function
<%=theJSON.replaceAll("\"", "\\\'")%>
That allows you to pass the JSON in,
then to get it back in JavaScript to normal JSON format
theJSON = theJSON.replace(/'/g,'"');
Should work fine

I think the combination of double quotes wrapping the onclick and the ones in your JSON may be messing you up. Think of it as if you entered the JSON manually -- it would look like this:
onclick="test('{ "id":1, "splits":[ { "texts":[ { "value":"Test", "locationX":3, "locationY":-153, "font":{ "type":"Normal", "size":"Medium", "bold":false, "colour":"5a5a5a", "italics":false } } ] } ] }'); return false;"
and the opening double quote before id would actually be closing the double quote following onclick= (You should be able to verify this by looking at the page source). Try specifying the onclick as:
onclick='test(\'<%=theJSON%>\'); return false;'

You can follow the following steps
Fetch the jon string
Using the jackson or any other JSON jar file , convert the json string to json array and print the string using out.println.
Call this jsp which prints the json string
check in the firebug , you will be able to see your json .
If the Json string does not print , there can be some problems in your json format.
this is a good website for json beautification , http://jsbeautifier.org/ , really makes the string simple to read .
Thanks
Abhi