Question

I have a .Net WCF Rest service returning Json to be consumed by an Android app.

In debug, the WCF service correctly has the return value (Json) as:

{"BaseLoyaltyPoints":1480,"BonusLoyaltyPoints":0,"BrandId":1414, [etc...] }

Also in debug, when it returns to Notepad, the return value has changed to:

{\"BaseLoyaltyPoints\":1480,\"BonusLoyaltyPoints\":0,\"BrandId\":1414, [etc...] }

And when it gets to my Android app, it has become:

{\\"BaseLoyaltyPoints\\":1480,\\"BonusLoyaltyPoints\\":0,\\"BrandId\\":1414, [etc...] }

This is the boilerplate code I am using to serialize the Json:

Dim stream1 As MemoryStream = New MemoryStream
Dim ser As DataContractJsonSerializer = New DataContractJsonSerializer(GetType(FullProduct))
ser.WriteObject(stream1, Me)

Dim _json As String = Encoding.UTF8.GetString(stream1.ToArray())
stream1.Close()

The Android code to get the Json is:

HttpClient httpclient = new DefaultHttpClient();
HttpGet request = new HttpGet(getString(R.string.CONST_RestService) + "/json/Product/" + productID);
ResponseHandler<String> handler = new BasicResponseHandler();       
result = httpclient.execute(request, handler);  
jObject = new JSONObject(result);

What’s going on?

Thanks

Dave

Answer 1

The JSON Data needs to be an evaluable JavaScript String – the ” character needs to be escaped to \” (the character ” as opposed to the String limitor “), and the \ in that expression needs to be escaped as well (because \ also is a special character). So it has been that string all along, it was just printed differently everytime.

Take this JavaScript for an example:

object = JSON.parse("{\"hello\":\"World\"}");
alert(object.hello);

The following is more of a guess than actual knowledge, because I do not know how exactly the classes you used behave, but I think that it’s about right.

As you can see, the " characters need to be escaped to \", so your .NET JSON serializer does just that. Everything is fine, interpreting this as JS would work as expected.

Now what is probably going on is that your JSONObject constructor does not expect Strings to be already properly escaped, so it does that itself. To clarify: When you say “with one escape character”, you probably mean something like this:

String workingJSONString = "{\"Hello\":\"World\"}"

right? The problem here is that Java has the same escaping rules as JavaScript – this is not what you get from your HTTPRequest, what you get is

String youGotThis = "{\\\"Hello\\\":\\\"World\\\"}"

Because there are literal backslashes in your String, and those need to be escaped as well. I am pretty certain that that is what is going on, and you’d probably either have to tell your .NET JSON serializer not to apply escape rules or find something that constructs a JSONObject from a properly escaped JSON string – or remove the unnecessary escapes yourself.

I hope this helped – but again, I am not fully certain so you should just check out if it actually behaves as I said.