javascript - Symfony - 自定义 FieldType form_widget 渲染

Question

简短的长问题，在对此进行了大量研究并找到了很多关于如何扩展现有字段类型、继承它们或更改后端某些内容的信息之后，但对于前端的实际渲染绝对没有，我是来问这个问题的。

手头“问题”的简短解释:我需要一个 EntityType 字段(ChoiceType - HTML Select)来使用我自己的过滤逻辑并动态地从 ajax 调用中提取结果，立即替换下拉列表中列出的选项。

当前代码(有效):在 FormType.php 中

//in buildForm
{
    $builder->add('trainer', EntityType::class, [
            'class' => Trainer::class,
            'choices' => $training->trainer_list ?? [],
            'label' => 'seminar.trainer.form.trainer.label',
            'placeholder' => 'form.trainer.placeholder',
            'required' => false,
            'attr' => ['class' => 'trainer2select'] // has no outcome whatsoever?!
        ])
    $builder->addEventListener(FormEvents::PRE_SUBMIT, [$this, 'onPreSubmit']);
}

function onPreSubmit(FormEvent $event) {
    $form = $event->getForm();
    $data = $event->getData();

    $trainer = $this->em->getRepository(Trainer::class)->find($data['trainer']);

    $form->add('trainer', EntityType::class, [
        'class' => Trainer::class,
        'data' => $trainer,
        'label' => 'seminar.trainer.form.trainer.label',
        'placeholder' => 'form.trainer.placeholder',
        'required' => false,
    ]);
}

在 Twig 上:

{% if field == 'trainer' %}
     {{ form_row(attribute(form, field), {'id': 'trainer'}) }}
{% else %}
     {{ form_row(attribute(form, field)) }}
{% endif %}

{% block javascripts %}
<script>
    var lastTime;
    var timeoutEvents = [];
    $(document).ready(() => {
        function trainer_changed() {
            let input = event.target;
            lastTime = Date.now();

            timeoutEvents.push(setTimeout(() => {
                if (Date.now() - lastTime < 150)
                    return;
                jQuery.ajax({
                    url: '{{ path('trainer_select_ajax') }}',
                    type: 'GET',
                    data: {
                        search: input.value,
                        start: {{ seminar.event.start.date | date('Y-m-d') }},
                        end: {{ seminar.event.end.date | date('Y-m-d') }}
                    },
                    success: function (trainers) {
                        let trainer = $('#trainer');
                        trainer.get(0).options.length = 1;  // reset all options, except for the default
                        trainers.forEach(tr => {
                            trainer.append(new Option(tr.text, tr.id));
                        });
                        let search = $($("input.select2-search__field").get(1));
                        if (search.get(0)) {
                            search.get(0).oninput = null;  // detach our event handler so we don't loop
                            search.trigger('input');  // rebuild the dropdown choices
                            search.get(0).oninput = trainer_changed;  // reattach our event handler
                        }
                    }
                });
                lastTime = Date.now();
                timeoutEvents.forEach(e => {
                    clearTimeout(e);
                });
            }, 200));
        }
        function select_opened() {
            let trainerinput = $('input.select2-search__field').get(1);
            if (trainerinput) {
                trainerinput.oninput = trainer_changed;
            }
        }
        $('#select2-trainer-container').click(select_opened);
    });
</script>
{% endblock %}

因此，显然 EntityType 字段是使用 select2 扩展呈现的。我显然可以用 javascript 替换功能，但我只想定义我自己的“AjaxEntityType”，让 form_widget 按我的意愿呈现。我可以在多个项目中使用的东西，而无需使用一些愚蠢的技巧，例如提供默认类名和调用 javascript 在全局页面加载后更改呈现。那么……怎么办？

我检查过的资源已被证明对我想要实现的目标毫无值(value):https://symfony.com/doc/current/form/form_customization.html , https://symfony.com/doc/current/form/form_themes.html还有更多。

编辑澄清:我正在寻找的最佳情况是自定义 FieldType 的简约示例，该示例始终呈现为 <select id="FieldTypeWidget"> ，将始终调用 $('#FieldTypeWidget').select2({ajax: {foo}, searchFunction: {bar}});

在 https://github.com/tetranz/select2entity-bundle我可以找到一个示例来说明如何在 bundle 中提供此功能，但是在我的应用程序中是否有更简单的方法？

Answer 1

我会说你正在看的是 this Symfony documentation page 中解释的内容

这是他们的示例，根据您的需要进行了一些修改:

src/Form/Type/AjaxEntityType.php

<?php

namespace App\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Form\Extension\Core\Type\EntityType;

class AjaxEntityType extends AbstractType
{
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            /**
             * This is the default of your field, 
             * add or remove based on your needs, 
             * your goal, is to only keep sensible defaults 
             * that you want on every single objects of this class
             */
            'required' => false,
        ]);
    }

    public function getParent()
    {
        return EntityType::class;
    }
}

这里是“魔法”发生的地方:
当你的类被称为 WhateverNameType 时，Symfony 只会删除它的 Type 部分并对其进行规范化(简化为 lcfirst 它)。
所以 WhateverNameType 将以 whateverName 结尾。
然后，您只需要知道在呈现 form_widget 中调用表单元素以结束正确的命名 block :whateverName_widget

templates/form/fields.html.twig

{% use 'form_div_layout.html.twig' %}

{% block ajaxEntity_widget %}
    {{ parent() }}
    <script>
        $('#{{ form.vars.id }}').select2({ajax: {foo}, searchFunction: {bar}});
    </script>
{% endblock %}

另请注意文档页面中的便捷提示:

You can further customize the template used to render each children of the choice type. The block to override in that case is named "block name" + entry + "element name" (label, errors or widget) (e.g. to customize the labels of the children of the Shipping widget you'd need to define {% block shipping_entry_label %} ... {% endblock %}).

还请记住，如稍后在同一页上所述，您的表单模板覆盖必须正确注册:

config/packages/twig.yaml

twig:
    form_themes:
        - 'form/fields.html.twig' 
        # you might have this configuration already, 
        # for example, if you use bootstrap theming. 
        # If so, just copy the configured template path stated here 
        # in the 'use' statement of the file form/fields.html.twig

然后直接使用它:

$builder->add('trainer', AjaxEntityType::class, [ class => Trainer::class, ]);

也值得一读:

• https://symfony.com/doc/4.2/form/form_themes.html#form-fragment-naming
• 发挥魔力的实际代码:https://github.com/symfony/symfony/blob/a0c566504cc4fedb4785199fabfc224e41afd1b8/src/Symfony/Component/Form/FormRenderer.php#L130