[SOLVED] how to get redirected url
lazarus / 38-Networking and Web Programming

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fan2006 · 2021-07-25 01:55

in c#,i can get the result from responseheaders("location") with set
allowredirects to false.but in fp i will get an 302 error with the
code "http.AllowRedirect := false".if i change it to true the code
could continue but the responseheaders do not contain the info of
location.how to solve it?
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses 
FphttpClient,OpensslSockets,Classes;  var    http:TfphttpClient;   
url:string;    response:TStringList;begin  url := 'http://www.baidu.co
m/link?url=ojjD2hHxviDl0j4T6MCQzRaQYUyYe0BX2aCXcNI5UliRtQum2Y7XH9_xZ08
mzOJH';  http:=TfphttpClient.Create(nil);  http.AllowRedirect :=
true;  http.AddHeader('user-agent','Mozilla/5.0'); 
response:=TStringList.Create;  http.get(url,response); 
writeln(http.ResponseHeaders.Text);  http.Free;  response.Free; 
readln;end.      





[Edited to add SOLVED to topic]

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rsz · 2021-07-25 06:34

I believe the cleanest solution is to extend the TFPHTTPClient class
and record/handle the redirects by setting the AllowRedirect to True
and setting OnRedirect to a method where you handle the redirects. You
could probably also just catch the 302 exception and manually handle
redirects, but that seems hacky to me.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
project1; uses  FphttpClient,OpensslSockets,Classes,sysutils; type  
TMyHttpClient = class(TFPHTTPClient)  private    FRedirects:
TStrings;    procedure HandleRedirect(Sender: TObject; Const ASrc:
String;      Var ADest: String);  public    constructor Create(AOwner:
TComponent); override;    destructor Destroy; override;    procedure
HTTPMethod(const AMethod, AURL: String;      Stream: TStream; const
AllowedResponseCodes: array of Integer); override;    property
Redirects: TStrings read FRedirects;  end;   constructor
TMyHttpClient.Create(AOwner: TComponent);  begin    inherited;   
FRedirects := TStringList.Create;    OnRedirect := @HandleRedirect; 
end;   destructor TMyHttpClient.Destroy;  begin    FRedirects.Free;  
inherited;  end;   procedure TMyHttpClient.HandleRedirect(Sender:
TObject; Const ASrc: String; Var ADest: String);  begin    { do
whatever you want per redirect, in this example we just add the     
redirect destination url to a list of strings }   
Redirects.Add(ADest);    { you can also access headers here if you
like }    //WriteLn(GetHeader(ResponseHeaders, 'Location'));  end;  
procedure TMyHttpClient.HTTPMethod(const AMethod, AURL: String;     
Stream: TStream; const AllowedResponseCodes: array of Integer); 
begin    { clear redirects list before initiating requests }   
Redirects.Clear;    inherited;  end; var  http:TMyHttpClient;  url,
RedirectUrl:string;  response:TStringList;begin  url := 'http://www.ba
idu.com/link?url=ojjD2hHxviDl0j4T6MCQzRaQYUyYe0BX2aCXcNI5UliRtQum2Y7XH
9_xZ08mzOJH';  http:=TMyHttpClient.Create(nil);  http.AllowRedirect :=
True;  http.AddHeader('user-agent','Mozilla/5.0'); 
response:=TStringList.Create;  http.get(url,response); 
writeln(http.ResponseHeaders.Text);   WriteLn;  WriteLn('We were
redirected ' + IntToStr(http.Redirects.Count) + ' times!');  for
RedirectUrl in http.Redirects do  begin    WriteLn(RedirectUrl); 
end;   http.Free;  response.Free;  readln;end.

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fan2006 · 2021-07-25 07:24

@rsz,thx for providing such a clear solution and it works fine.