How to create a TSvnItem for a specified URL - delphi

Question

Short Version
How to perform svn cat in Delphi's subversion api wrapper?
Long Version
I want to get the contents of a file in subversion.
Here's a random public repository that lets you cat (i.e. display the contents of) a file:
>svn cat http://svn.code.sf.net/p/unicon/code/trunk/unicon/README
Unicon 13.x README
This is the Unicon distribution. Please tell us
where it compiles, and when and how it doesn't.
...snip...
So that works.
Now how to do it in Delphi?
How do i read the contents (i.e. cat) a file in Delphi's Subversion API wrapper?
Based on this Stackoverflow answer, i try:
SvnItem: TSvnItem;
SvnItem := TSvnItem.Create(SvnClient, nil, 'http://svn.code.sf.net/p/unicon/code/trunk/unicon/README');
Unfortunately the call to create a TSvnItem throws an exception:
EAprError: The given path is misformatted or contained invalid characters
So what am i doing wrong?
For The Lazy
program Project1;
{$APPTYPE CONSOLE}
uses
SysUtils, SvnClient;
procedure Main;
var
SvnClient: TSvnClient;
SvnItem: TSvnItem;
url: string;
begin
// Set the global variable where the subversion DLLs can be found.
BaseDllDir := ExtractFilePath(ParamStr(0)); //Setting a global variable (yes, seriously)
SvnClient := TSvnClient.Create;
SvnClient.Initialize;
url := 'http://svn.code.sf.net/p/unicon/code/trunk/unicon/README';
SvnItem := TSvnItem.Create(SvnClient, nil, url);
end;
begin
try
Main;
except
on E: Exception do
begin
ExitCode := 1;
Writeln(Format('[%s] %s', [E.ClassName, E.Message]));
end;
end;
end.
See also
https://sourceforge.net/projects/radstudioverins/
Programmatically adding, deleting and committing files into a subversion repository using Delphi
reading SVN:externals from working copy

Answer 1

It's not an answer; but it is a workaround for the next guy.
Thing that should work (but doesn't)
function GetSubversionFileContents(Client: TSvnClient; Url: string): TStream;
var
item: TSvnItem;
buffer: TBytes;
ms: TMemoryStream;
begin
//WARNING: This code doesn't work.
item := TSvnItem.Create(Client, nil, Url); //throws exception
buffer := item.GetBaseFile;
item.Free;
ms := TMemoryStream.Create;
ms.Size := Length(buffer);
if Length(buffer) > 0 then
ms.Write(buffer[0], Length(buffer));
ms.Seek(0, soFromBeginning);
end;
Hack workaround
function GetSubversionFileContents(Client: TSvnClient; Url: string): TStream;
var
http: IWinHttpRequest;
stm: IStream;
begin
// Issue the WebDAV HTTP GET ourselves.
// (SVN is just a wrapper around WebDAV)
http := CoWinHttpRequest.Create;
http.Open('GET', url, False);
if Client.UserName <> '' then
http.SetCredentials(Client.UserName, Client.Password, HTTPREQUEST_SETCREDENTIALS_FOR_SERVER);
http.Send(EmptyParam);
stm := IUnknown(http.ResponseStream) as IStream;
Result := TOleStream.Create(stm);
//TODO: Re-write the rest of the Subversion API into something modern (i.e. post-1995).
end;
Subversion is just an implementation of WebDAV - which is just REST but without the cool name. Which means you can issue a GET to the url to get the contents yourself directly.