Object could not be converted to string?

Question

Why am I getting this error:

Catchable fatal error: Object of class Card could not be converted to string in /f5/debate/public/Card.php on line 79

Here is the code:

public function insert() {
            $mysql = new DB(debate);

            $this->initializeInsert();

            $query = "INSERT INTO cards VALUES('$this->$type','$this->$tag','$this->$author->$last','$this->$author->$first','$this->$author->$qualifications','$this->$date->$year','$this->$date->$month','$this->$date->$day','$this->$title', '$this->$source', '$this->$text')";
            $mysql->execute($query);
        }

(Line 79 is the $query and the function is part of class "Card")

All the declarations of "Card":

    public $type;

    public $tag;
    public $title;
    public $source;
    public $text;

    public function __construct() {
        $this->date = new Date;
        $this->author = new Author;
    }

---

After changing line 79 to this:

$query = "INSERT INTO cards VALUES('$this->type','$this->tag','$this->author->last','$this->author->first','$this-$author->qualifications','$this->date->year','$this->date->month','$this->date->day','$this->title', '$this->source', '$this->text')";

I now get this error:

Catchable fatal error: Object of class Author could not be converted to string in /f5/debate/public/Card.php on line 79

Answer 1

you shouldn't put $ before property names when you access them:

public function insert() {
        $mysql = new DB(debate);
        $this->initializeInsert();
        $query = "INSERT INTO cards VALUES('$this->type','$this->tag','$this->author->last','$this->author->first','$this-$author->qualifications','$this->date->year','$this->date->month','$this->date->day','$this->title', '$this->source', '$this->text')";
        $mysql->execute($query);
    }

Answer 2

You are trying to echo an object itself, not a string property of it. Check your code carefully.

Answer 3

You probably want to use:

$query = "INSERT INTO cards VALUES('$this->type','$this->tag' // etc

Answer 4

I don't think you need the $ sign when using arrow operator.

Answer 5

Read about string parsing, you have to enclose the variables with brackets {}:

$query = "INSERT INTO cards VALUES('$this->type','$this->tag','{$this->author->last}',"

Whenever you want to access multidimensional arrays or properties of a property in string, you have to enclose this access with {}. Otherwise PHP will only parse the variable up to the first [i] or ->property.

So with "$this->author->last" instead of "{$this->author->last}", PHP will only parse and evaluate $this->author which gives you the error as author is an object.

Answer 6

I think one of the object doesn't have toString() method defined so it cannot be represented as string.