How do you populate a Magento_UI dynamicRows element?

Question

I've got a <dynamicRows> element. When I render the object, I'm able to create new rows, and all of the fields appear.

However, I have no idea how to:

1. Populate the rows from the database
2. Save the rows back into the database

I've been looking at vendor\magento\module-swatches\view\adminhtml\ui_component\product_attribute_add_form.xml as a reference, and the only element that looks remotely like "data" is:

<item name="valuesForOptions" xsi:type="array">
 <item name="swatch_text" xsi:type="string">swatch_text</item>
</item>

But I can't figure out how that works, and what the "swatch_text" parameter does.

I've also added a <dataProvider> tag, but I'm not sure where to add it. I've added my UI xml below:

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd"> 
<button>
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="displayAsLink" xsi:type="boolean">true</item>
 <item name="title" xsi:type="string">Test</item>
 <item name="actions" xsi:type="array">
 <item name="0" xsi:type="array">
 <item name="targetName" xsi:type="string">product_form.product_form.business_card_modal</item>
 <item name="actionName" xsi:type="string">toggleModal</item>
 </item>
 </item>
 </item>
 </argument>
</button>
<modal name="business_card_modal">
 <settings>
 <options>
 <option name="buttons" xsi:type="array">
 <item name="0" xsi:type="array">
 <item name="text" xsi:type="string">Done</item>
 <item name="class" xsi:type="string">action-primary</item>
 <item name="actions" xsi:type="array">
 <item name="0" xsi:type="array">
 <item name="targetName" xsi:type="string">${ $.name }</item>
 <item name="actionName" xsi:type="string">actionDone</item>
 </item>
 </item>
 </item>
 </option>
 <option name="title" xsi:type="string">Business Card?</option>
 </options>
 <onCancel>actionDone</onCancel>
 <dataScope>data.product</dataScope>
 </settings>
 <dataSource name="mm_bizcard_data_source">
 <argument name="data" xsi:type="array">
 <item name="js_config" xsi:type="array">
 <item name="component" xsi:type="string">Magento_Ui/js/form/provider</item>
 </item>
 </argument>
 <settings>
 <validateUrl path="catalog/product_attribute/validate"/>
 <submitUrl path="catalog/product_attribute/save"/>
 </settings>
 <dataProvider class="MM\Bizcard\Model\Product\DataProvider" name="mm_bizcard_data_source">
 <settings>
 <requestFieldName>id</requestFieldName>
 <primaryFieldName>attribute_id</primaryFieldName>
 </settings>
 </dataProvider>
 </dataSource>
 <fieldset name="my_fieldset" class="MM\Bizcard\Ui\Component\Form\Fieldset">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="valuesForOptions" xsi:type="array">
 <item name="swatch_text" xsi:type="string">swatch_text</item>
 </item>
 <item name="label" xsi:type="string" translate="true">Bizcard Thing 2</item>
 <item name="sortOrder" xsi:type="number">1000</item>
 </item>
 </argument>
 <dynamicRows name="bizcard">
 <settings>
 <addButtonLabel translate="true">Add Label</addButtonLabel>
 <componentType>dynamicRows</componentType>
 </settings>
 <container name="record" component="Magento_Ui/js/dynamic-rows/record">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="isTemplate" xsi:type="boolean">true</item>
 <item name="is_collection" xsi:type="boolean">true</item>
 <item name="componentType" xsi:type="string">container</item>
 <item name="positionProvider" xsi:type="string">attribute_options.position</item>
 </item>
 </argument>
 <field name="testfield" component="Magento_Catalog/js/form/element/input" formElement="input">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="prefixName" xsi:type="string">option.order</item>
 <item name="prefixElementName" xsi:type="string">option_</item>
 </item>
 </argument>
 <settings>
 <dataType>text</dataType>
 <visible>true</visible>
 </settings>
 </field>
 <field name="position" component="Magento_Catalog/js/form/element/input" formElement="input">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="prefixName" xsi:type="string">option.order</item>
 <item name="prefixElementName" xsi:type="string">option_</item>
 </item>
 </argument>
 <settings>
 <additionalClasses>
 <class name="_hidden">true</class>
 </additionalClasses>
 <dataType>text</dataType>
 <visible>false</visible>
 <dataScope>position</dataScope>
 </settings>
 </field>
 <actionDelete>
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="componentType" xsi:type="string">actionDelete</item>
 <item name="dataType" xsi:type="string">text</item>
 <item name="label" xsi:type="string">Actions</item>
 <item name="sortOrder" xsi:type="string">100</item>
 </item>
 </argument>
 </actionDelete>
 </container>
 </dynamicRows>
 </fieldset>
</modal>
</form> 

How do I populate <dynamicRows> with data on page load?

Answer 1

Your <form> element seems to be missing it's configuration. You should have something like this:

 <argument name="data" xsi:type="array">
 <item name="js_config" xsi:type="array">
 <item name="provider" xsi:type="string">some_form.your_data_source</item>
 <item name="deps" xsi:type="string">some_form.your_data_source</item>
 </item>
 <item name="label" xsi:type="string" translate="true">Some Form</item>
 <item name="config" xsi:type="array">
 <item name="dataScope" xsi:type="string">data</item>
 <item name="namespace" xsi:type="string">some_form</item>
 </item>
 <item name="template" xsi:type="string">templates/form/collapsible</item>
 <item name="buttons" xsi:type="array">
 ...
 </item>
 </argument>

Where 'your_data_source' is the name supplied to the <dataSource>

The provider argument to the js_config is what makes the data source visible to the form.

Also, <dataSource> should be under <form>, not <modal>