[fpc-pascal] TFPHttpClient & TFPHttpServer

[Michael Van Canneyt]

On Tue, 3 Jan 2023, duilio foschi via fpc-pascal wrote:

> I would like to write some code where a TFPHttpClient component sends
> a minimal json payload to a TFPHttpServer that (reads the payload).
>
> The working of the TFPHttpClient component is clear enough, while its
> counterpart TFPHttpServer proves rather obscure to me.
>
> TFPHttpClient
> ===========
> Page  https://wiki.freepascal.org/fphttpclient
> contains complete and clear code:
>
>
> var
>  Client: TFPHttpClient;
>  Response: TStringStream;
>  Params: string = '{"Name": "John", "Age": 32}';
> begin
>  Client := TFPHttpClient.Create(nil);
>  Client.AddHeader('User-Agent', 'Mozilla/5.0 (compatible; fpweb)');
>  Client.AddHeader('Content-Type', 'application/json; charset=UTF-8');
>  Client.AddHeader('Accept', 'application/json');
>  Client.AllowRedirect := true;
>  Client.UserName := USER_STRING;
>  Client.Password := PASSW_STRING;
>  Client.RequestBody := TRawByteStringStream.Create(Params);
>  Response := TStringStream.Create('');
>  try
>    try
>      Client.Post(TheURL, Response);
>      Writeln('Response Code: ' +
> IntToStr(Client.ResponseStatusCode)); // better be 200
>    except on E: Exception do
>      Writeln('Something bad happened: ' + E.Message);
>    end;
>  finally
>    Client.RequestBody.Free;
>    Client.Free;
>    Response.Free;
>  end;
>
> I reckon I need to set - say-
> TheURL:='http://localhost:9200';
> here
>
>
> TFPHTTPServer
> =============
>
> say we use
> TTestHTTPServer=class(TFPHTTPServer);
> for our server,
>
> I understand that all action takes place inside procedure
> DataModuleRequest (so far so good):
>
> procedure TTestHTTPServer.DataModuleRequest(Sender: TObject; ARequest: TRequest;
> AResponse: TResponse; var Handled: Boolean);
> begin
>   //
> end;
>
> Q1: how can I create an object of type jsondata from ARequest?

include fpjson and jsonparser units in your uses clause. Then do


JSON :=GetJSON(aRequest.Content);


>
> Q2: can I get a UTF8 string from ARequest?

Yes, aRequest.Content is a string.

>
> Q3: TFPHTTPServer has property Port. I reckon it will be set to 9200
> here. Is it correct?

Yes.

>
> Q4: TFPHTTPServer has property Address. I reckon it will be set to
> 'localhost' here. Is it correct?

It depends on what you want. Best is to leave it empty.

>
> Q5: TFPHTTPServer has no property Username and Password. How do I
> check the values I set in the corresponding properties of
> TFPHTTPClient?

aRequest.Authorization will be a string of the form

Basic NNNNNNN

Where NNNNN is a base64 encoded string with username:password in it.
So you must decode the string (see bas64 unit) and split the resulting
string in username and password.

>
> Q6: what is the use of parameter Handled?

If Handled is false, then an error will be sent to the client.
You should set Handled to true.

Michael.