Post JSON data to RESTful datasnap server from delphi client - web-services

Question

I need to send a simple JSON object to a Restful datasnap server (Delphi) from a Delphi client. I am using Delphi XE. Can anybody help me out with the code? I am trying for hours but not getting it.. Please ask if details are not sufficient
Edit:
Here is server side method declaration:
procedure updatemethodnme(str:string):string;
and here is client side code:
function PostData(request: string): boolean;
var
param: TStringList;
url, Text,str: string;
code: Integer;
http: TIDHttp;
begin
Result:= false;
http:= TIDHttp.Create(nil);
http.HandleRedirects:= true;
http.ReadTimeout:= 50000;
http.request.Connection:= 'keep-alive';
str:= '{"lamp":"'+lamp+'","floor":"'+floor+'","op":"'+request+'"}';
param:= TStringList.Create;
param.Clear;
param.Add(str);
url:= 'h***p://xx2.168.xx.xx:xxxx/Datasnap/rest/TserverMethods1/methdname/';
try
Text:= http.Post(url, param);
Result:= true;
except on E: Exception do
begin
Result := false;
end;
end;
end;

Answer 1

Here's some simple XE2 test code sending JSON data through HTTP Post using SuperObject (using Indy's TIdHTTP):
procedure TFrmTTWebserviceTester.Button1Click(Sender: TObject);
var
lJSO : ISuperObject;
lRequest: TStringStream;
lResponse: String;
begin
// Next 2 lines for Fiddler HTTP intercept:
IdHTTP.ProxyParams.ProxyServer := '127.0.0.1';
IdHTTP.ProxyParams.ProxyPort := 8888;
lJSO := SO('{"name": "Henri Gourvest", "vip": true, "telephones": ["000000000", "111111111111"], "age": 33, "size": 1.83, "adresses": [ { "adress": "blabla", "city": "Metz", "pc": 57000 }, { "adress": "blabla", "city": "Nantes", "pc": 44000 } ]}');
lRequest := TStringStream.Create(lJSO.AsString, TEncoding.UTF8);
try
IdHTTP.Request.ContentType := 'application/json';
IdHTTP.Request.Charset := 'utf-8';
try
lResponse := IdHTTP.Post('http://127.0.0.1:8085/ttposttest', lRequest);
ShowMessage(lResponse);
except
on E: Exception do
ShowMessage('Error on request:'#13#10 + E.Message);
end;
finally
lRequest.Free;
end;
lJSO := nil;
end;
This is the data that goes out:
POST http://127.0.0.1:8085/ttposttest HTTP/1.0
Content-Type: application/json; charset=utf-8
Content-Length: 204
Connection: keep-alive
Host: 127.0.0.1:8085
Accept: text/html, */*
Accept-Encoding: identity
User-Agent: Mozilla/3.0 (compatible; Indy Library)
{"vip":true,"age":33,"telephones":["000000000","111111111111"],"adresses":[{"adress":"blabla","pc":57000,"city":"Metz"},{"adress":"blabla","pc":44000,"city":"Nantes"}],"size":1.83,"name":"Henri Gourvest"}
Receiver is a TWebAction on a TWebModule, with handler:
procedure TWebModuleWebServices.WebModuleWebServicesTTPostTestAction(
Sender: TObject; Request: TWebRequest; Response: TWebResponse;
var Handled: Boolean);
var
S : String;
lJSO: ISuperObject;
begin
S := Request.Content;
if S <> '' then
lJSO := SO('{"result": "OK", "encodingtestcharacters": "Typed € with Alt-0128 Will be escaped to \u20ac"}')
else
lJSO := SO('{"result": "Error", "message": "No data received"}');
Response.ContentType := 'application/json'; // Designating the encoding is somewhat redundant for JSON (http://stackoverflow.com/questions/9254891/what-does-content-type-application-json-charset-utf-8-really-mean)
Response.Charset := 'utf-8';
Response.Content := lJSO.AsJSON;
Handled := true;
end; { WebModuleWebServicesTTPostTestAction }
It uses TIdHTTPWebBrokerBridge:
FWebBrokerBridge := TIdHTTPWebBrokerBridge.Create(Self);
// Register web module class.
FWebBrokerBridge.RegisterWebModuleClass(TWebModuleWebServices);
// Settings:
FWebBrokerBridge.DefaultPort := 8085;
This is the actual response:
HTTP/1.1 200 OK
Connection: close
Content-Type: application/json; charset=utf-8
Content-Length: 92
{"encodingtestcharacters":"Typed\u20acwithAlt0128FollowedBy8364escaped\u8364","result":"OK"}

Answer 2

You can use Indy's TIdHTTP component to Post() JSON-encoded data to a REST server. You would simply have to encode and decode the JSON data in your own code.

Answer 3

From Delphi6 posting to a datasnap server built in XE5 the above works for me, but I had found out the server method needed the parameter to be defined as a TJSONObject instead of TStream. Something odd in addition to this, the Datansap server changes the lookup method when you do a post instead of a get. For example I had a method named ImportData. But when you debug the server it was looking for an UpdateImportData method. So when I added the new method and changed the parameter type to Data.DBXJSON.TJSONObject it worked.