Does the ulkJSON library have limitations when dealing with base64 in Delphi 7?
- by Da Gopherboy
I'm working on a project that is using Delphi 7 to consume RESTful services. We are creating and decoding JSON with the ulkJSON library. Up to this point I've been able to successfully build and send JSON containing a base64 string that exceed 5,160kb. I can verify that the base64 is being received by the services and verify the integrity of the base64 once its there. In addition to sending, I can also receive and successfully decode JSON with a smaller (~ 256KB or less) base64.
However I am experiencing some issues on the return trip when larger (~1,024KB+) base64 is involved for some reason. Specifically when attempting to use the following JSON format and function combination:
JSON:
{
"message" : "/9j/4AAQSkZJRgABAQEAYABgAAD...."
}
Function:
function checkResults(JSONFormattedString: String): String;
var
jsonObject : TlkJSONObject;
iteration : Integer;
i : Integer;
x : Integer;
begin
jsonObject := TlkJSONobject.Create;
// Validate that the JSONFormatted string is not empty.
// If it is empty, inform the user/programmer, and exit from this routine.
if JSONFormattedString = '' then
begin
result := 'Error: JSON returned is Null';
jsonObject.Free;
exit;
end;
// Now that we can validate that this string is not empty, we are going to
// assume that the string is a JSONFormatted string and attempt to parse it.
//
// If the string is not a valid JSON object (such as an http status code)
// throw an exception informing the user/programmer that an unexpected value
// has been passed. And exit from this routine.
try
jsonObject := TlkJSON.ParseText(JSONFormattedString) as TlkJSONobject;
except
on e:Exception do
begin
result := 'Error: No JSON was received from web services';
jsonObject.Free;
exit;
end;
end;
// Now that the object has been parsed, lets check the contents.
try
result := jsonObject.Field['message'].value;
jsonObject.Free;
exit;
except
on e:Exception do
begin
result := 'Error: No Message received from Web Services '+e.message;
jsonObject.Free;
exit;
end;
end;
end;
As mentioned above when using the above function, I am able to get small (256KB and less) base64 strings out of the 'message' field of a JSON object. But for some reason if the received JSON is larger than say 1,024kb the following line seems to just stop in its tracks:
jsonObject := TlkJSON.ParseText(JSONFormattedString) as TlkJSONobject;
No errors, no results. Following the debugger, I can go into the library, and see that the JSON string being passed is not considered to be JSON despite being in the format listed above. The only difference I can find between calls that work as expected and calls that do not work as expect appears to be the size of base64 being transmitted.
Am I missing something completely obvious and should be shot for my code implementation (very possible)? Have I missed some notation regarding the limitations of the ulkJSON library? Any input would be extremely helpful. Thanks in advance stack!
