Question

问题

我在php中有这个Task类：

class Task{
public $title;
public $due_date;
public $priority;
public $course;
public $note;

function __construct($title, $due_date, $priority, $course, $note) {
    $this->title = $title;
    $this->due_date = $due_date;
    $this->priority = $priority;
    $this->course = $course;
    $this->note = $note;
}

public function is_empty(){
    return ($this->title === '' || $this->due_date === '' || $this->priority === '' || $this->course ==='' || $this->note ==='');
}
}

但是当我尝试使用is_empty()时，它无法正常工作（并且会停止以下所有功能）：

            //If valid form elements & not a duplicate, add it to data file
            if($valid_title && $valid_note && $valid_date){
                $task = task_from_form();
                //Don't add duplicates or tasks with empty elements
                echo "work please"; //prints
                $is_empty = $task->is_empty();
                echo "$is_empty"; //doesn't print
                if(!$is_empty && !in_array($task, $tasks)){
                    //write task to file
                    write_file($filename, $task);
                    //add task to gloabl var tasks
                    $tasks[] = $task;
                }
            }

我不确定我制作的语法错误，并且我确定它有些愚蠢，所以任何建议都会非常感谢！

代码

task_from_form()函数（但我知道这可以使用b / c我之前没有调用$task->is_empty()使用过它）：

//Return task from form elements
function task_from_form(){
    if(isset($_POST['submit']) && isset($_POST['title']) && isset($_POST['note'])){     
        if($_POST['title'] !== '' && $_POST['note'] !== ''){
            $title = $_POST['title'];
            $note = $_POST['note'];
            $title_trim = trim($title);
            $note_trim = trim($note);
            $title_html = htmlentities($title_trim);
            $note_html = htmlentities($note_trim);

            $due_date = $_POST['due-date'];
            $priority = $_POST['priority'];
            $course = $_POST['course'];
            $course_space = str_replace("-", " ", $course);

            $task = new Task($title_html, $due_date, $priority, $course_space, $note_html);

            return $task; 
        }
    }
}

Answer 1

感谢@MagnusEriksson＆amp; @JustOnUnderMillions评论我意识到$task = task_from_form()正在返回null，因为return语句嵌套在if语句中。因此，如果if语句未评估为true，则task_from_form()将返回null。然后我会在null is_empty()上调用实例方法$task。所以我在操作is_null($task)之前使用$task来检查null。

我还了解了find errors如何使用MAMP！老实说这是b / c的主要问题我在调试之前不知道该怎么做是非常困难的

固定代码

                //If valid form elements & not a duplicate, add it to data file
            if($valid_title && $valid_note && $valid_date){
                $task = task_from_form();
                //Make sure task is not null
                if(!is_null($task)){
                    //Don't add duplicates
                    if(!$task->is_empty() && !in_array($task, $tasks)){
                        //write task to file
                        write_file($filename, $task);
                        //add task to gloabl var tasks
                        $tasks[] = $task;
                    }
                }
            }

为什么简单的布尔php实例函数不起作用？

问题

代码

1 个答案:

固定代码