Unable to unselect all multiselect values

[Vinai]

Magento version: 2.1.2

It is not possible to unselect and save all multiselect attribute values for a product.
After the save completes the state of the product attribute before the product was saved is unchanged.
It seems the problem is that the JS does not submit multiselect form elements with no selected values, at least on the server side completely unselected multiselect attribtues are not part of the $_POST['product'] array.

The exact same issue existed for years on M1 but was finally fixed there. It seems like this issue was introduced again for M2.

Preconditions

None special.

Steps to reproduce

1. Create a custom multiselect attribute. Ot just install the sample data (e.g. the issue can be reproduced using the features_bag or strap_bags attributes).
2. Open the product in the admin interface.
3. Select one or more values of the multiselect attribtue.
4. Save
5. Unselect all values of the multiselect attribute
6. Save again

Expected result

The product attribute should have no value for the product.

Actual result

The previously selected product attributes still are selected.

[Vinai]

@fooman gave the input that probably the can_be_empty property has to be set on the \Magento\Framework\Data\Form\Element\Multiselect instance.
For system configuration multiselect that can be done by adding the <can_be_empty> node to the system.xml file, but in case of EAV attributes I see no obvious way to do so since they are DB based.

[Vinai]

On a side note, the method \Magento\Framework\Data\Form\Element\Multiselect::getElementHtml() adds the CSS class admin__control-multiselect (amongst others). Should the class not also be usable on the store front?

[Vinai]

More info in case it's useful: the property can_be_empty would be set in \Magento\Backend\Block\Widget\Form::_applyTypeSpecificConfig() but that method is never called. There are 3 classes that would trigger the flow of control to enter that method, but none of three classes are used on the edit product form. Is this M1 legacy code that wasn't deleted?

\Magento\Catalog\Block\Adminhtml\Product\Edit\Action\Attribute\Tab\Attributes::_prepareForm()
\Magento\Catalog\Block\Adminhtml\Product\Attribute\NewAttribute\Product\Attributes::_prepareForm()
\Magento\Catalog\Block\Adminhtml\Product\Edit\Tab\Attributes::_prepareForm()

[ivanweiler]

It seems that same problem exists with configuration multiselects. For example
Stores>Configuration>General>Top destinations - not possible to unselect all and save in 2.1.2.

[antboiko]

Hi @Vinai , thanks for reporting this issue. We have internal ticket MAGETWO-57607 to track this issue on our side.

Best,
Anton.

[pravalitera]

It happens also on custom attributes with custom sources. I have put Magento\Eav\Model\Entity\Attribute\Backend\ArrayBackend as backend_model .

When i save in backoffice without options, i have a string in the before save with the previous options selected.
When i save in backoffice with one/more options, i have an array.

[erikhansen]

@antboiko Any update on this issue? A Magento Enterprise merchant I'm working with is experiencing this issue and they're looking for a patch. Before emailing support for a patch, I wanted to see if this was fixed in develop so that I can grab a patch?

[wsagen]

Any update on this?

[roseofgold]

I'd like to know how to get this fixed. It's driving me nuts. (Tested on both 2.1.2 and 2.1.6)

[redelschaap]

Bug is still present in 2.1.5.

[nkajic]

Seems like duplicate of #6253 #6281 #4545
and that this is fixed by
https://github.com/nagno/magento2/commit/b380502570b92449326ab6ed50e6ce0359287240

[drobinson]

@veloraven @magento-engcom-team Do you know where this was fixed for the 2.1 branch? I see the backport commit here but this does not fix the issue for me (introduces a new issue): 7ec8952

If there's a better place for me to describe the issue please let me know.

[WilliamChongSDG]

This issue still persist in Magento ver. 2.2.2

[danielmaier42]

Still present in Magento ver. 2.2.3

[mathieu-f]

I had the same issue because of multiselect having an empty value (ie. equal to '' or 0 or null) :

<select multiple="" class="admin__control-multiselect" data-bind="
    attr: {
        name: inputName,
        id: uid,
        size: size ? size : '6',
        disabled: disabled,
        'aria-describedby': noticeId,
        placeholder: placeholder
    },
    hasFocus: focused,
    optgroup: options,
    selectedOptions: value,
    optionsValue: 'value',
    optionsText: 'label'" name="product[customer_group]" id="MEAKNUP" size="6" aria-describedby="notice-MEAKNUP">
   <option data-title="NOT LOGGED IN" value="0">NOT LOGGED IN</option> <!-- here is the devil -->
   <option data-title="General" value="1">General</option>
   <option data-title="Conseillère" value="2">Conseillère</option>
</select>

Magento\Catalog\Controller\Adminhtml\Product\Initialization\Helper\AttributeFilter prepare your attributes before saving it.

public function prepareProductAttributes(Product $product, array $productData, array $useDefaults)
{
    foreach ($productData as $attribute => $value) {
        $considerUseDefaultsAttribute = !isset($useDefaults[$attribute]) || $useDefaults[$attribute] === "1";
        if ($value === '' && $considerUseDefaultsAttribute) {
            /** @var $product Product */
            if ((bool)$product->getData($attribute) === (bool)$value) {
                unset($productData[$attribute]);
            }
        }
    }
    return $productData;
}

When a posted value is equal to empty string ('') it will compare it to the product value before saving.
The issue is that Magento cast both values in boolean. And when the previously selected product value was set to 0 (like "NOT LOGGED IN" in our example) it compares an empty string casted in boolean (= false) with a 0 casted in boolean (= false too) so the value is simply unset ... so the attribute isn't saved and there is no error.

In our specific case, we fixed it using a plugin to restore the value after the prepareProductAttributes function has been called.

I hope it will help.

[likemusic]

Why this issue is closed?

[VladimirZaets]

@likemusic

Why this issue is closed?

• This issue isn't reproduced on current 2.2 and 2.3 Magento branch

[devamitbera]

Still this issue also persist at magento 2.2.4 .

Have done with Vinai describe scenario and same issue is happening

@Vinai ,Is this issue resolved at your end?

@magento/community-engineering-team ,Can you please check this issue again

[aurelius15]

I hope this will help someone.
di.xml

<type name="\Magento\Catalog\Controller\Adminhtml\Product\Initialization\Helper\AttributeFilter">
        <plugin name="Vendor_Module::prepareProductAttributes" type="\Vendor\Module\Plugin\Product\AttributeFilter"/>
    </type>

Plugin\AttributeFilter.php

use \Magento\Catalog\Controller\Adminhtml\Product\Initialization\Helper\AttributeFilter as AttributeFilterHelper;

public function afterPrepareProductAttributes(AttributeFilterHelper $subject, $result, $product, $productData)
    {
        foreach ($productData as $attribute => $value) {
            $pos = strripos($attribute, '-prepared-for-send');
            if ($pos === false) {
                continue;
            }
            $attr = substr($attribute, 0, $pos);
            if (isset($result[$attr])) {
                continue;
            }
            $result[$attr] = '';
        }
        return $result;
    }

[ihor-sviziev]

@engcom-backlog-nazar @engcom-backlog-nickolas could you please recheck if this issue still there?
People were complaining that it wasn’t fixed

[ghost]

@ihor-sviziev, ok i will re check this issue

[magento-engcom-team]

Hi @engcom-backlog-nazar. Thank you for working on this issue.
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[ghost]

@ihor-sviziev seems like this already fixed in 2.3.0 release

[aurelius15]

@engcom-backlog-nazar

1. Select some attribute items and save
2. unselect all items this attribute and try to save

[ghost]

@aurelius15 same with

unselect all items this attribute and try to save

[ihor-sviziev]

@engcom-backlog-nazar did you checked this issue on 2.2 release line?

[ghost]

@ihor-sviziev yes, same on 2.2-develop

[ghost]

@ihor-sviziev can we close this issue ?

[ihor-sviziev]

@engcom-backlog-nazar sure, if we can’t reproduce this issue

[wenpingguo]

I cannot find the fix.
Can we have a patch for the fixes?
Many thanks

[adm-sport]

i have the same issue for the 2.2.8.. Does the 2.2.x have a fix for that? we are unable to unselect all values :'(

[lano-vargas]

Still an issue on 2.3.5 I'm facing same issue. key pair value not set in the post when all values are deselected.
Note: Fixed multi select in system.xml with can_be_empty.

[wasimhc]

It works on vendor\magento\module-payment\etc\adminhtml\system.xml
It also works on custom module too. If showInStore is used for multiselect and its 's showInStore is not specified, can_be_empty doesn't work at my end. If showInStore is removed from multiselect field in this case, can_be_empty works.