course.lib.php

完美的在线教育系统

			if (Database::num_rows($handle) == 0)
			{
				return false; // the user isn't registered to the platform
			}
			else
			{
				//check if user isn't already subscribed to the course
				$handle = api_sql_query("SELECT * FROM ".$course_user_table."
																	WHERE `user_id` = '$user_id'
																	AND `course_code` ='$course_code'", __FILE__, __LINE__);
				if (Database::num_rows($handle) > 0)
				{
					return false; // the user is already subscribed to the course
				}
				else
				{
					$course_sort = CourseManager :: userCourseSort($user_id,$course_code);
					$add_course_user_entry_sql = "INSERT INTO ".$course_user_table."
										SET `course_code` = '$course_code',
										`user_id`    = '$user_id',
											`status`    = '".$status."',
											`sort`  =   '". ($course_sort)."'";
					$result = api_sql_query($add_course_user_entry_sql, __FILE__, __LINE__);
					if ($result)
					{
						return true;
					}
					else
					{
						return false;
					}
				}
			}
		}
	}

	/**
	* Subscribe a user $user_id to a course $course_code.
	* @author Hugues Peeters
	* @author Roan Embrechts
	*
	* @param  int $user_id the id of the user
	* @param  string $course_code the course code
	* @param string $status (optional) The user's status in the course
	*
	* @return boolean true if subscription succeeds, boolean false otherwise.
	* @todo script has ugly ifelseifelseifelseif structure, improve
	*/
	function add_user_to_course($user_id, $course_code, $status = STUDENT)
	{
		$user_table = Database :: get_main_table(TABLE_MAIN_USER);
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);
		$course_user_table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);

		$status = ($status == STUDENT || $status == COURSEMANAGER) ? $status : STUDENT;
		if (empty($user_id) || empty ($course_code))
		{
			return false;
		}
		else
		{
			// previously check if the user are already registered on the platform

			$handle = api_sql_query("SELECT status FROM ".$user_table."
								WHERE `user_id` = '$user_id' ", __FILE__, __LINE__);
			if (Database::num_rows($handle) == 0)
			{
				return false; // the user isn't registered to the platform
			}
			else
			{
				//check if user isn't already subscribed to the course
				$handle = api_sql_query("SELECT * FROM ".$course_user_table."
																	WHERE `user_id` = '$user_id'
																	AND `course_code` ='$course_code'", __FILE__, __LINE__);
				if (Database::num_rows($handle) > 0)
				{
					return false; // the user is already subscribed to the course
				}
				else
				{
					// previously check if subscription is allowed for this course

					$handle = api_sql_query("SELECT code, visibility FROM ".$course_table."
											WHERE  `code` = '$course_code'
											AND  `subscribe` = '".SUBSCRIBE_NOT_ALLOWED."'", __FILE__, __LINE__);

					if (Database::num_rows($handle) > 0)
					{
						return false; // subscription not allowed for this course
					}
					else
					{
						$max_sort = api_max_sort_value('0', $user_id);
						$add_course_user_entry_sql = "INSERT INTO ".$course_user_table."
											SET `course_code` = '$course_code',
												`user_id`    = '$user_id',
												`status`    = '".$status."',
												`sort`  =   '". ($max_sort +1)."'";
						$result=api_sql_query($add_course_user_entry_sql, __FILE__, __LINE__);
						if ($result)
						{
							return true;
						}
						else
						{
							return false;
						}
					}
				}
			}
		}
	}

	/**
	*	This code creates a select form element to let the user
	*	choose a real course to link to.
	*
	*	A good non-display library should not use echo statements, but just return text/html
	*	so users of the library can choose when to display.
	*
	*	We display the course code, but internally store the course id.
	*
	*	@param boolean $has_size, true the select tag gets a size element, false it stays a dropdownmenu
	*	@param boolean $only_current_user_courses, true only the real courses of which the
	*	current user is course admin are displayed, false all real courses are shown.
	*	@param string $element_name the name of the select element
	*	@return a string containing html code for a form select element.
	* @deprecated Function not in use
	*/
	function get_real_course_code_select_html($element_name, $has_size = true, $only_current_user_courses = true, $user_id)
	{
		if ($only_current_user_courses == true)
		{
			$real_course_list = CourseManager :: get_real_course_list_of_user_as_course_admin($user_id);
		}
		else
		{
			$real_course_list = CourseManager :: get_real_course_list();
		}

		if ($has_size == true)
		{
			$size_element = "size=\"".SELECT_BOX_SIZE."\"";
		}
		else
		{
			$size_element = "";
		}
		$html_code = "<select name=\"$element_name\" $size_element >\n";
		foreach ($real_course_list as $real_course)
		{
			$course_code = $real_course["code"];
			$html_code .= "<option value=\"".$course_code."\">";
			$html_code .= $course_code;
			$html_code .= "</option>\n";
		}
		$html_code .= "</select>\n";

		return $html_code;
	}

	/**
	*	Checks wether a parameter exists.
	*	If it doesn't, the function displays an error message.
	*
	*	@return true if parameter is set and not empty, false otherwise
	*	@todo move function to better place, main_api ?
	*/
	function check_parameter($parameter, $error_message)
	{
		if (!isset ($parameter) || empty ($parameter))
		{
			Display :: display_normal_message($error_message);
			return false;
		}
		return true;
	}

	/**
	*	Lets the script die when a parameter check fails.
	*	@todo move function to better place, main_api ?
	*/
	function check_parameter_or_fail($parameter, $error_message)
	{
		if (!CourseManager :: check_parameter($parameter, $error_message))
			die();
	}

	/**
	*	@return true if there already are one or more courses
	*	with the same code OR visual_code (visualcode), false otherwise
	*/
	function is_existing_course_code($wanted_course_code)
	{
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);

		$sql_query = "SELECT COUNT(*) as number FROM ".$course_table."WHERE `code` = '$wanted_course_code' OR `visual_code` = '$wanted_course_code' ";
		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);
		$result = Database::fetch_array($sql_result);

		if ($result["number"] > 0)
		{
			return true;
		}
		else
		{
			return false;
		}
	}

	/**
	*	@return an array with the course info of all real courses on the platform
	*/
	function get_real_course_list()
	{
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);
		$sql_query = "SELECT * FROM $course_table WHERE `target_course_code` IS NULL";
		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);

		while ($result = Database::fetch_array($sql_result))
		{
			$real_course_list[] = $result;
		}

		return $real_course_list;
	}

	/**
	*	@return an array with the course info of all virtual courses on the platform
	*/
	function get_virtual_course_list()
	{
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);
		$sql_query = "SELECT * FROM $course_table WHERE `target_course_code` IS NOT NULL";
		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);

		while ($result = Database::fetch_array($sql_result))
		{
			$virtual_course_list[] = $result;
		}
		return $virtual_course_list;
	}

	/**
	*	@return an array with the course info of the real courses of which
	*	the current user is course admin
	*/
	function get_real_course_list_of_user_as_course_admin($user_id)
	{
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);
		$course_user_table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);

		$sql_query = "	SELECT *
										FROM $course_table course
										LEFT JOIN $course_user_table course_user
										ON course.`code` = course_user.`course_code`
										WHERE course.`target_course_code` IS NULL
											AND course_user.`user_id` = '$user_id'
											AND course_user.`status` = '1'";

		//api_display_debug_info($sql_query);
		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);

		while ($result = Database::fetch_array($sql_result))
		{
			$result_array[] = $result;
		}

		return $result_array;
	}

	/**
	*	@return an array with the course info of all the courses (real and virtual) of which
	*	the current user is course admin
	*/
	function get_course_list_of_user_as_course_admin($user_id)
	{
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);
		$course_user_table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);

		$sql_query = "	SELECT *
										FROM $course_table course
										LEFT JOIN $course_user_table course_user
										ON course.`code` = course_user.`course_code`
										WHERE course_user.`user_id` = '$user_id'
											AND course_user.`status` = '1'";

		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);

		while ($result = Database::fetch_array($sql_result))
		{
			$result_array[] = $result;
		}

		return $result_array;
	}

	/**
	* Find out for which courses the user is registered and determine a visual course code and course title from that.
	* Takes virtual courses into account
	*
	* Default case: the name and code stay what they are.
	*
	* Scenarios:
	* - User is registered in real course and virtual courses; name / code become a mix of all
	* - User is registered in real course only: name stays that of real course
	* - User is registered in virtual course only: name becomes that of virtual course
	* - user is not registered to any of the real/virtual courses: name stays that of real course
	* (I'm not sure about the last case, but this seems not too bad)
	*
	* @author Roan Embrechts
	* @param $user_id, the id of the user
	* @param $course_info, an array with course info that you get using Database::get_course_info($course_system_code);
	* @return an array with indices
	*    $return_result["title"] - the course title of the combined courses
	*    $return_result["code"]  - the course code of the combined courses
	*/
	function determine_course_title_from_course_info($user_id, $course_info)
	{
		$real_course_id = $course_info['system_code'];
		$real_course_info = Database :: get_course_info($real_course_id);
		$real_course_name = $real_course_info["title"];
		$real_course_visual_code = $real_course_info["visual_code"];
		$real_course_real_code = $course_info['system_code'];

		//is the user registered in the real course?
		$table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
		$sql_query = "SELECT * FROM $table WHERE `user_id` = '$user_id' AND `course_code` = '$real_course_real_code'";
		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);
		$result = Database::fetch_array($sql_result);

		if (!isset ($result) || empty ($result))
		{
			$user_is_registered_in_real_course = false;
		}
		else
		{
			$user_is_registered_in_real_course = true;
		}
		//get a list of virtual courses linked to the current real course
		//and to which the current user is subscribed

		$user_subscribed_virtual_course_list = CourseManager :: get_list_of_virtual_courses_for_specific_user_and_real_course($user_id, $real_course_id);

		if (count($user_subscribed_virtual_course_list) > 0)
		{
			$virtual_courses_exist = true;
		}
		else
		{