Magento 2.1 products grid serializer's values are not sending in form post

Question

I am working on admin form where i have a product's grid in edit form.It shows products in grid but when i check products and save form data product's checked values are not posted along with other fields.

Here is code.

in ui component i have added this code

<fieldset name="assign_products">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="label" xsi:type="string" translate="true">Attach Products</item>
            <item name="collapsible" xsi:type="boolean">true</item>
            <item name="sortOrder" xsi:type="number">40</item>
        </item>
    </argument>
    <container name="assign_products_container" >
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="sortOrder" xsi:type="number">160</item>
            </item>
        </argument>
        <htmlContent name="html_content">
            <argument name="block" xsi:type="object">companyname\modulename\Block\Adminhtml\Faqs\AssignProducts</argument>
        </htmlContent>
    </container>
</fieldset> 

in companyname\modulename\Block\Adminhtml\Faqs\AssignProducts

<?php

/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace companyname\modulename\Block\Adminhtml\Faqs;

class AssignProducts extends \Magento\Backend\Block\Template
{
    /**
     * Block template
     *
     * @var string
     */
    protected $_template = 'catalog/category/edit/assign_products.phtml';

    /**
     * @var \Magento\Catalog\Block\Adminhtml\Category\Tab\Product
     */
    protected $blockGrid;

    /**
     * @var \Magento\Framework\Registry
     */
    protected $registry;

    /**
     * @var \Magento\Framework\Json\EncoderInterface
     */
    protected $jsonEncoder;

    /**
     * AssignProducts constructor.
     *
     * @param \Magento\Backend\Block\Template\Context $context
     * @param \Magento\Framework\Registry $registry
     * @param \Magento\Framework\Json\EncoderInterface $jsonEncoder
     * @param array $data
     */
    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Framework\Registry $registry,
        \Magento\Framework\Json\EncoderInterface $jsonEncoder,
        array $data = []
    ) {
        $this->registry = $registry;
        $this->jsonEncoder = $jsonEncoder;
        parent::__construct($context, $data);
    }

    /**
     * Retrieve instance of grid block
     *
     * @return \Magento\Framework\View\Element\BlockInterface
     * @throws \Magento\Framework\Exception\LocalizedException
     */
    public function getBlockGrid()
    {

        if (null === $this->blockGrid) {
            $this->blockGrid = $this->getLayout()->createBlock(
                'company\modulename\Block\Adminhtml\Faqs\Tab\Product',
                'category.product.grid'
            );
        }
        return $this->blockGrid;
    }

    /**
     * Return HTML of grid block
     *
     * @return string
     */
    public function getGridHtml()
    {

        return $this->getBlockGrid()->toHtml();
    }

    /**
     * @return string
     */
    public function getProductsJson()
    {
        $products = $this->getCategory()->getProductsPosition();
        if (!empty($products)) {
            return $this->jsonEncoder->encode($products);
        }
        return '{}';
    }
    /**
     * Retrieve current category instance
     *
     * @return array|null
     */
    public function getCategory()
    {
        return $this->registry->registry('faqs');
    }
}

and in company\module\Block\Adminhtml\Faqs\Tab\Product

<?php

class Product extends \Magento\Backend\Block\Widget\Grid\Extended
{

    protected $productCollectionFactory;

    protected $faqsFactory;

    protected $registry;
    protected $_objectManager = null;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Backend\Helper\Data $backendHelper,
        \Magento\Framework\Registry $registry,
        \Magento\Framework\ObjectManagerInterface $objectManager,
        FaqsFactory $faqsFactory,
        \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
        array $data = []
    ) {
        $this->faqsFactory = $faqsFactory;
        $this->productCollectionFactory = $productCollectionFactory;
        $this->_objectManager = $objectManager;
        $this->registry = $registry;
        parent::__construct($context, $backendHelper, $data);
    }

    protected function _construct()
    {

        parent::_construct();
        $this->setId('productsGrid');
        $this->setDefaultSort('entity_id');
        $this->setUseAjax(true);

    }

    protected function _addColumnFilterToCollection($column)
    {
        // Set custom filter for in category flag
        if ($column->getId() == 'in_product') {
            $productIds = $this->_getSelectedProducts();
            if (empty($productIds)) {
                $productIds = 0;
            }
            if ($column->getFilter()->getValue()) {
                $this->getCollection()->addFieldToFilter('entity_id', ['in' => $productIds]);
            } elseif (!empty($productIds)) {
                $this->getCollection()->addFieldToFilter('entity_id', ['nin' => $productIds]);
            }
        } else {
            parent::_addColumnFilterToCollection($column);
        }
        return $this;
    }
    /**
     * prepare collection
     */
    protected function _prepareCollection()
    {
        $collection = $this->productCollectionFactory->create();
        $collection->addAttributeToSelect('name');
        $collection->addAttributeToSelect('sku');
        $collection->addAttributeToSelect('price');
        $this->setCollection($collection);
        return parent::_prepareCollection();
    }
    /**
     * @return $this
     */
    protected function _prepareColumns()
    {

        $model = $this->_objectManager->get('\company\m\Model\Faqs');
        $this->addColumn(
            'in_product',
            [
                'header_css_class' => 'a-center',
                'type' => 'checkbox',
                'name' => 'in_product',
                'align' => 'center',
                'index' => 'entity_id',
                'values' => $this->_getSelectedProducts(),
            ]
        );
        $this->addColumn(
            'entity_id',
            [
                'header' => __('Product ID'),
                'type' => 'number',
                'index' => 'entity_id',
                'header_css_class' => 'col-id',
                'column_css_class' => 'col-id',
            ]
        );
        $this->addColumn(
            'name',
            [
                'header' => __('Name'),
                'index' => 'name',
                'class' => 'xxx',
                'width' => '50px',
            ]
        );
        $this->addColumn(
            'sku',
            [
                'header' => __('Sku'),
                'index' => 'sku',
                'class' => 'xxx',
                'width' => '50px',
            ]
        );
        $this->addColumn(
            'price',
            [
                'header' => __('Price'),
                'type' => 'currency',
                'index' => 'price',
                'width' => '50px',
            ]
        );
        return parent::_prepareColumns();
    }
    /**
     * @return string
     */
    public function getGridUrl()
    {
       // echo "tttttt";
       // exit;
        return $this->getUrl('*/*/productsgrid', ['_current' => true]);
    }
    /**
     * @param  object $row
     * @return string
     */
    public function getRowUrl($row)
    {
        return '';
    }
    protected function _getSelectedProducts()
    {
        $faq = $this->getFaqObj();
        return $faq->getProducts($faq);
    }
    /**
     * Retrieve selected products
     *
     * @return array
     */
    public function getSelectedProducts()
    {
        $faq = $this->getFaqObj();
        $selected = $faq->getProducts($faq);
        if (!is_array($selected)) {
            $selected = [];
        }
        return $selected;
    }
    protected function getFaqObj()
    {
        $faqId = $this->getRequest()->getParam('faq_id');
        $faq   = $this->faqsFactory->create();
        if ($faqId) {
           $faq->load($faqId);
        }
        return $faq;
    }
    /**
     * {@inheritdoc}
     */
    public function canShowTab()
    {
        return true;
    }
    /**
     * {@inheritdoc}
     */
    public function isHidden()
    {
        return true;
    }
}

Answer 1

I faced the same problem solved it by adding modulename_edit in data-form-part="modulename_edit"ui component name. hope it will some one else too

$blockGrid = $block->getBlockGrid();
$gridJsObjectName = $blockGrid->getJsObjectName();

?>
<?php  echo $block->getGridHtml(); ?>
<input type="text" name="category_products" id="in_category_products" data-form-part="modulename_edit" value="" />
<script type="text/x-magento-init">
    {
        "*": {
            "NameSpace_Modulename/js/assign_product": {
                "selectedProducts": <?php /* @escapeNotVerified */ echo $block->getProductsJson(); ?>,
                "gridJsObjectName": <?php /* @escapeNotVerified */ echo '"' . $gridJsObjectName . '"' ?: '{}'; ?>
            }
        }
    }
</script>
<!-- @todo remove when "UI components" will support such initialization -->
<script>
    require('mage/apply/main').apply();
</script>