Names of database tables and columns

netteman

Hi

If I want to use something like this

$book->author->name

do I have to use the naming of database tables and columns used is this example https://doc.nette.org/…ase/explorer

https://files.nette.org/…chema-1-.png

I'm asking because if I tweaked the name of tables and columns I could use

$book->author

(this variable would be eg. 2) but

$book->author->name

gave me an error.

Thanks :)

Šaman

Without code it is hard to tell.

netteman

The following code/database does not work

<?php

namespace App\Presenters;

use Nette;
use App\Model;

**Presenter**
class HomepagePresenter extends BasePresenter
{

    private $database;

    public function __construct(Nette\Database\Context $database)
    {
        $this->database = $database;

    }//end mtd


    public function renderDefault()
    {
            $this->template->books = $this->database->table("book");

    }//end mtd

}//end class

Template
{block content}

<h1 n:block=“title”>Books</h1>

{foreach $books as $book}
<div class=“book”>

<h2>{$book->title}</h2>

<div>{$book->author->name}</div>

</div>
{/foreach}

{/block}

Error
Trying to get property of non-object
<div><?php echo Latte\Runtime\Filters::escapeHtml($book->author->name, ENT_NOQUOTES) ?></div>

-- Adminer 4.2.1 MySQL dump

SET NAMES utf8;

CREATE TABLE author (
id_author int(11) NOT NULL AUTO_INCREMENT,
name varchar(100) COLLATE utf8_bin NOT NULL,
PRIMARY KEY (id_author)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

CREATE TABLE book (
id int(11) NOT NULL AUTO_INCREMENT,
author int(11) NOT NULL,
title varchar(100) COLLATE utf8_bin NOT NULL,
PRIMARY KEY (id),
KEY author (author),
CONSTRAINT book_ibfk_1 FOREIGN KEY (author) REFERENCES author (id_author)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

If I change the database to this, everything works.
author.id_author → author.id
book.author → book.author_id

-- Adminer 4.2.1 MySQL dump

SET NAMES utf8;

CREATE TABLE author (
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(100) COLLATE utf8_bin NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

CREATE TABLE book (
id int(11) NOT NULL AUTO_INCREMENT,
author_id int(11) NOT NULL,
title varchar(100) COLLATE utf8_bin NOT NULL,
PRIMARY KEY (id),
KEY author_id (author_id),
CONSTRAINT book_ibfk_1 FOREIGN KEY (author_id) REFERENCES author (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

Do you need to know anything else?

Last edited by netteman (2016-04-29 20:13)

David Matějka

This is expected behavior. If the column is named author and you use $book->author then nette returns column value (id of an author). You would have to use $book->ref('author') which returns referenced row.

However if the joining column is named author_id (or e.g. id_author) and you use $book->author then there is no such column. So nette tries to find some association, which has a joining column that contains given string. In this case, it finds author_id and returns referenced row.

netteman

Thanks :)