How to set default value in config.xml file for tables in Magento2 backend system configuration

Question

To create a table configuration in Magento2 backend, we can use some good tutorial in here: http://www.ibnab.com/en/blog/magento-2/magento-2-backend-guide-to-create-table-setting-in-the-system-configuration or https://magently.com/blog/magento-2-backend-configuration-frontend-model-part-33/

I read this tutorial in Magento 1 https://www.integer-net.com/how-to-create-tables-in-magento-system-configuration/.

They created a table configuration with default value. I knew that in Magento 1, we can set default array value for table in config.xml like that:

<default>
    <namespace_module>
        <settings>
            <shipping_costs>a:1:{s:18:"_1425462208957_957";a:2:{s:10:"from_price";s:1:"0";s:4:"cost";s:4:"4.90";}}</shipping_costs>
        </setting>
    </namespace_module>
</default>

I try to put the same array above from Magento 1 to config.xml file on Magento 2, but it does not work at all.

Here is my example:

system.xml:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
<system>
    <tab id="media" translate="label" sortOrder="300">
        <label>MEDIA</label>
    </tab>
    <section id="payment" translate="label" type="text" sortOrder="402" showInDefault="1" showInWebsite="1" showInStore="1">
        <label>Settings</label>
        <tab>media</tab>            
        <group id="setting" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
            <field id="interest_rates" translate="label comment" sortOrder="13" showInDefault="1" showInWebsite="0" showInStore="0">
                <label>Interest Rates</label>
                <frontend_model>Company\Module\Block\Adminhtml\System\Config\Fieldset\InterestRates</frontend_model>
                <backend_model>Magento\Config\Model\Config\Backend\Serialized\ArraySerialized</backend_model>                    
            </field>
        </group>
    </section>  
<system>    

File InterestRates

protected function _prepareToRender()
{
    $this->addColumn('duration', ['label' => __('Duration'), 'style' => 'width:60px']);
    $this->addColumn('effective_interest_rate', ['label' => __('Effective Interest Rate'), 'style' => 'width:170px']);
    $this->addColumn('special_effective_interest_rate', ['label' => __('Special Effective Interest Rate'), 'style' => 'width:170px']);
    $this->_addAfter = false;
    $this->_addButtonLabel = __('Add Interest Rate');
}

Picture demo

I want to set default value for text column Duration, Effective_Interest_Rate and Special Effective Interest Rate

Can someone give me an advice? How can I set default value for table configuration in Magento .

Answer 1

In your case, you can follow the same Magento 1 way, you have to enter a serialized array there. From my experience, the best way to generate that serialized array is to fill in the default data in the backend, save it and then copy the value from core_config_data table to the config.xml.

For example config xml:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <payment>
            <setting>
                <interest_rates>a:4:{s:18:"_1477023122716_716";a:3:{s:4:"from";s:1:"0";s:2:"to";s:5:"10000";s:3:"fee";s:3:"324";}s:18:"_1477023174715_715";a:3:{s:4:"from";s:5:"10001";s:2:"to";s:5:"30000";s:3:"fee";s:3:"432";}s:18:"_1477023192619_619";a:3:{s:4:"from";s:5:"30001";s:2:"to";s:6:"100000";s:3:"fee";s:3:"648";}s:18:"_1477023219483_483";a:3:{s:4:"from";s:6:"100001";s:2:"to";s:6:"300000";s:3:"fee";s:4:"1080";}}</interest_rates>
            </setting>
        </payment>
    </default>
</config>

We can use this site http://www.unserialize.com/ to check our serialized array.

Answer 2

Below code for set yes value to dropdown file Yes/No.

In config.xml file,

<?xml version="1.0"?>


<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <payment>
            <setting>
                <interest_rates>100</interest_rates>
            </setting>
        </payment>
    </default>
</config>

Answer 3

Sample for new carrier. You can easily set default value for all types of fields

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <carriers>
            <poczta_shipment>
                <active>1</active>
                <model>Your\PathTo\Model\Carrier</model>
                <name>Poczta Polska</name>
                <price>15.00</price>
                <title>Poczta</title>
                <tracking_url>url_for_tracking_code</tracking_url>
            </poczta_shipment>
        </carriers>
    </default>
</config>

EDIT:

Cant You use something like that:

    $this->addColumn('duration', ['label' => __('Duration'), 'style' => 'width:60px', 'default' => 'xxx']);

or

    $this->addColumn('duration', ['label' => __('Duration'), 'style' => 'width:60px', 'value' => 'xxx']);