symfony2 ContextErrorException：Catchable Fatal Error：类Proxies \\ __ CG __ \\ ... \\ Entity \\ ...的对象无法转换为字符串

Question

I have encountered something weird:

I created three doctrine entities via app/console doctrine:generate:entity :

• Category
• User
• Post

I set up the relationships and everything works fine with the fixtures data ( app/console doctrine:fixtures:load ).

A post belongs to a single category (category_id), and has one author (user_id).

I used app/console doctrine:generate:crud to get CRUD operations for all my entities.

When I update a post, I get this strange error:

ContextErrorException: Catchable Fatal Error: Object of class Proxies__CG__...\\BlogBundle\\Entity\\Category could not be converted to string

In order to correctly display the dropdown fields I use in PostType() :

$builder ....
  ->add('categoryId','entity', array(
     'class' => 'HotelBlogBundle:Category',
     'property'=>'name'
))
->add('userId','entity',array(
     'class'=>'UserBundle:User',
     'property'=>'username'
))

Since I specify the property option I don't need a __toString() in my Entity classes.

If I create a __toString() like this (both in Category & User Entities), the error is gone and works:

public function __toString()
{
    return (string) $this->getId();
}

I am not sure if I do it the right way.

Also, since a Category & User object is passed to category_id and user_id fields, Doctrine (or Symfony) should be able to figure out the id column. What am I missing? Is there another way of doing this?

Answer 1

I just ran into this issue with the mentioned error (and ended up here), I'll post the solution that worked for me - seeing as there are no other answers.

Like the OP, I also created a new table and join using Doctrine.

This error is telling us that the joined object cannot be converted to a string . We have to either provide a __toString() method in the object so it can be converted to a string, or we can specify which field we want to return in our Form Builder using the property key.

Add a __toString() method to your object

/**
 * (Add this method into your class)
 *
 * @return string String representation of this class
 */
public function __toString()
{
    return $this->name;
}

OR add the property key to your form builder

// where `name` equals your field name you want returned
$builder->add('category', null, ['property' => 'name'])

I simply added the __toString() method to my entity , I only have the fields id and name - so the only string representation is the name .

Answer 2

In symfony 3, you can't use property.

Here the error message : The option "property" does not exist. ...

It's because the entity field doesn't use the option "property" anymore ( documentation ).

You should use the option "choice_label" instead.