Consistent 404 from custom module URL... Why?

Question

I'm trying to make a really simple module to add the Category Thumbnail back to Magento 2.2.1 and having a real time with it. I've been working on this simple issue for many hours, and read many pages with no real progress.

Here's my app/code/Tridium/Thumbnail/etc/adminhtml/routes.xml file:

<?xml version="1.0"?>

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="admin">
        <route id="thumbnail" frontName="thumbnail">
            <module name="Tridium_Thumbnail" />
        </route>
    </router>
</config>

And my app/code/Tridium/Thumbnail/view/adminhtml/ui_component/category_form.xml file:

<?xml version="1.0" encoding="UTF-8"?>

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="content">
        <field name="thumbnail">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="dataType" xsi:type="string">string</item>
                    <item name="source" xsi:type="string">category</item>
                    <item name="label" xsi:type="string" translate="true">Category Thumbnail</item>
                    <item name="visible" xsi:type="boolean">true</item>
                    <item name="formElement" xsi:type="string">fileUploader</item>
                    <item name="elementTmpl" xsi:type="string">ui/form/element/uploader/uploader</item>
                    <item name="previewTmpl" xsi:type="string">Magento_Catalog/image-preview</item>
                    <item name="required" xsi:type="boolean">false</item>
                    <item name="sortOrder" xsi:type="number">40</item>
                    <item name="uploaderConfig" xsi:type="array">
                        <item name="url" xsi:type="url" path="thumbnail/image/upload"/>
                    </item>
                </item>
            </argument>
        </field>
    </fieldset>
</form>

The controller is at app/code/Tridium/Thumbnail/Controller/Adminhtml/Image/Upload.php.

The thumbnail image field appears just fine on the Category Form, but it will not upload because the URL continually throws a 404.

The URL it is attempting to upload the file to looks like:

<admin_path>/thumbnail/image/upload

Please, any thoughts about this?

I've looked around to see if there is a way to output all the parsed routes, but there doesn't seem to be. It seems that would be a really helpful addition to the magento binary...

Answer 1

Can you please add before attribute and try again.

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="admin">
        <route id="thumbnail" frontName="thumbnail">
            <module name="Tridium_Thumbnail" before="Magento_Backend" />
        </route>
    </router>
</config>

Please flush the cache.