Delphi7 Indy HTTPServer not getting form parameters - html

Question

I have an Indy 10 IdHTTPServer in a Windows application which serves a virtual HTML form with two text boxes and a submit button. When the button is pressed in the browser I am not seeing any form params returned to the server.
Note that this is a bit of proof of concept code which will be used to make a windows service respond to button presses in a web form.
The HTML form is like this:
<form action="http://<addressofsite>/" method="post">
First name:<br>
<input type="text" name="firstname" value="Mickey"><br>
Last name:<br>
<input type="text" name="lastname" value="Mouse"><br><br>
<input type="submit" value="Submit">
</form>
in the Delphi code I have this:
procedure TForm1.HTTPServer1CommandGet(AThread: TIdPeerThread;
ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
begin
...
if ARequestInfo.Command = 'POST' then
begin
{******* POSTS ***************}
Memo1.Text := ARequestInfo.RawHTTPCommand;
end;
end;
I have tried various bits of the ARequestInfo structure but whatever I try all I see when the button is pressed in the browser is:
POST / HTTP 1.1
No params appear to be passed.
I'm obviously doing something wrong, so please can someone point out my idiocy.
Update:
As pointed out by The Arioch below, I should have checked that the browser is actually sending the data - so using Chrome developer tools I examined the headers, the results of which are:
Response Headers
Connection:close
Content-Type:text/html
Server:Indy/10.0.52
Request Headers
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image /webp,*/*;q=0.8
Accept-Encoding:gzip, deflate, br
Accept-Language:en-GB,en-US;q=0.8,en;q=0.6
Authorization:Basic YWRtaW46cGFzcw==
Cache-Control:max-age=0
Connection:keep-alive
Content-Length:31
Content-Type:application/x-www-form-urlencoded
Host:127.0.0.1:8091
Origin:http://127.0.0.1:8091
Referer:http://127.0.0.1:8091/main
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36
Form Data
firstname:Mickey
lastname:Mouse
So the browser is definitely sending the form data.

Answer 1

The raw encoded form data is stored in the ARequestInfo.FormParams and ARequestInfo.UnparsedParams properties.
If TIdHTTPServer.ParseParams is true (which it is by default), the decoded form data is stored in the ARequestInfo.Params property, eg:
procedure TForm1.HTTPServer1CommandGet(AThread: TIdPeerThread;
ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
var
FirstName, LastName: string;
begin
...
if (ARequestInfo.CommandType = hcPOST) and
IsHeaderMediaType(ARequestInfo.ContentType, 'application/x-www-form-urlencoded') then
begin
FirstName := ARequestInfo.Params.Values['firstname'];
LastName := ARequestInfo.Params.Values['lastname'];
...
end;
end;
Note that TIdHTTPServer is a multi-threaded component. The various events, including OnCommandGet, are fired in the context of worker threads. So, if you need to touch UI controls, like your TMemo, you must synchronize with the main UI thread, eg:
procedure TForm1.HTTPServer1CommandGet(AThread: TIdPeerThread;
ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
begin
...
if (ARequestInfo.CommandType = hcPOST) and
HeaderIsMediaType(ARequestInfo.ContentType, 'application/x-www-form-urlencoded') then
begin
TThread.Synchronize(nil,
procedure
begin
Memo1.Text := ARequestInfo.Params.Text;
end
);
...
end;
end;
Also, 10.0.52 is an outdated version of Indy. The current version (at the time of this writing) is 10.6.2.5384.