How to move things around in UI Components in magento2?

Question

I want to move fields on customer/index/edit. Creating another fieldset can be done with

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
<fieldset name="my-new-fields">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="label" xsi:type="string" translate="true">Additional Information</item>
        </item>
    </argument>
    <field name="blablupp">
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="label" translate="true" xsi:type="string">buueeyyy</item>
                <item name="visible" xsi:type="boolean">true</item>
                <item name="dataType" xsi:type="string">text</item>
                <item name="formElement" xsi:type="string">input</item>
                <item name="source" xsi:type="string">customer</item>
            </item>
        </argument>
    </field>
</fieldset>

And even hiding a field from an existing fieldset is easy by adding to the customer fieldset:

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
<fieldset name="customer">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="label" xsi:type="string" translate="true">Additional Information</item>
        </item>
    </argument>
    <field name="prefix">
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="visible" xsi:type="boolean">false</item>
        </argument>
    </field>
</fieldset>

But what I really want is to move a field from customer to another to simplify life for unexperienced admin users. How is that accomplished?

Answer 1

I am going to answer my own question:

I want to have a fieldset "company" in an separate tab with field "company_name" in customer edit form. The eav attribute is saved in customer entity.

Create the file Vendor\Module\view\adminhtml\ui_component\customer_form.xml

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="customer">
        <fieldset name="company">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="label" xsi:type="string">My custom fieldset</item>
                </item>
            </argument>
            <field name="company_name">
                <argument name="data" xsi:type="array">
                    <item name="config" xsi:type="array">
                        <item name="label" xsi:type="string">Firma</item>
                        <item name="visible" xsi:type="boolean">true</item>
                        <item name="dataScope" xsi:type="string">company_name</item>
                        <item name="dataType" xsi:type="string">varchar</item>
                        <item name="formElement" xsi:type="string">input</item>
                        <item name="sortOrder" xsi:type="number">5</item>
                        <item name="imports" xsi:type="array">
                            <item name="default" xsi:type="string">${ $.provider }:data.customer.company_name</item>
                        </item>
                    </item>
                </argument>
            </field>
        </fieldset>
    </fieldset>
</form>

Note the item. That imports the data form customer fieldset into my custom fieldset. But that only reads data. To alo write it back to the customer entity I needed to create an observer:

events.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="adminhtml_customer_prepare_save">
        <observer instance="Vendor\Module\Observer\Customer\AdminhtmlCustomerSaveBefore" name="vendor_module_observer_adminhtml_customer_save_before"/>
    </event>
</config>

Observer class:

<?php

namespace Vendor\Module\Observer\Customer;

use Magento\Customer\Model\Customer; 
use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;

class AdminhtmlCustomerSaveBefore implements ObserverInterface
{
    public function execute(
        Observer $observer
    )
    {
        /** @var  Customer $customer */
        $customer = $observer->getEvent()->getCustomer();
        $params = $observer->getEvent()->getRequest()->getParams();
        if (isset($params['company']['company_name'])) {
            $customer->setCustomAttribute('company_name', $params['company']['company_name']);

    }
}