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如何强制将收藏收藏变成单向下下下菜单?
原标题:How to Force a Collection to be a Single Drop down menu in a form

我想为下面的用户角色收集建立一个单滴 dwon 菜单 :

  class UserType extends AbstractType
    {
        public function buildForm(FormBuilder $builder, array $options)
        {
            $builder
                ->add( userRoles ,null, array( multiple =>false))
            ;
        }

但我得到这个错误信息:

Expected an object, but got a collection. Did you forget to pass
"multiple=true" to an entity field?

任何想法如何使收藏无法多重选择?

最佳回答

您使用的字段类型 (“实体”) 如果设置“ 倍数” 错误, 则您需要将一个简单对象作为输入。 为了您的目的, 您可能想要使用调回转换格式在收藏和对象之间转换 :

$builder->add(
    $builder->create( userRoles , null, array( multiple  => false))
        ->addModelTransformer(new CallbackTransformer(
            // transform the collection to its first element
            function (Collection $coll) { return $coll[0]; },
            // transform the element to a collection
            function (MyEntity $entity) { return new ArrayCollection(array($entity)); }
        ))
);

如果您不使用最新的 Symfony2 母版, 您应该使用 < code> prependnNorm Transfer () 而不是 < code > admodel Transfer ()

问题回答

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