HttpRouterParameters topic

Declaration

HttpRouterParameters

Description

Routes can include parameters using pattern matching with colon notation. Parameters are extracted from the URL path and made available to handlers through string lists. This enables RESTful URL patterns like /users/:id or /users/:uid/posts/:pid.

program ParameterRouter;

{$mode objfpc}{$H+}

uses
  httproute, httpdefs, Classes, SysUtils;

procedure HandleUser(ARequest: TRequest; AResponse: TResponse);
var
  Params: TStringList;
  UserID: String;
begin
  Params := TStringList.Create;
  try
    // Extract parameters from the route
    if HTTPRouter.GetHTTPRoute(ARequest.PathInfo, rmGet, Params) <> nil then
    begin
      if Params.Count > 0 then
        UserID := Params[0]
      else
        UserID := 'unknown';
      AResponse.Content := 'User ID: ' + UserID;
    end
    else
      AResponse.Content := 'No route found';
  finally
    Params.Free;
  end;
end;

procedure HandleUserPosts(ARequest: TRequest; AResponse: TResponse);
var
  Params: TStringList;
  UserID, PostID: String;
begin
  Params := TStringList.Create;
  try
    if HTTPRouter.GetHTTPRoute(ARequest.PathInfo, rmGet, Params) <> nil then
    begin
      UserID := 'unknown';
      PostID := 'unknown';
      if Params.Count > 0 then UserID := Params[0];
      if Params.Count > 1 then PostID := Params[1];
      AResponse.Content := Format('User %s, Post %s', [UserID, PostID]);
    end
    else
      AResponse.Content := 'No route found';
  finally
    Params.Free;
  end;
end;

begin
  HTTPRouter.RegisterRoute('/user/:id', rmGet, @HandleUser, False);
  HTTPRouter.RegisterRoute('/user/:uid/post/:pid', rmGet, @HandleUserPosts, False);

  Writeln('Parameter routing examples:');
  Writeln('GET /user/123 - Shows user 123');
  Writeln('GET /user/456/post/789 - Shows post 789 for user 456');
end.