How to add min value for a field in custom Module system.xml file?

Question

I want to add minimum value attribute for a admin interface field in my custom module. Can anyone suggest me how I can add min attribute in field? Here is my system.xml code:

<field id="uspsintexpress" translate="label" type="text" sortOrder="70" showInDefault="1" showInWebsite="1" showInStore="1">
<label>USPS Int'l Express Days</label>
</field>

Answer 1

Option 1

You can add minimum value validation by backend_model, for example.

<field id="base_url" translate="label comment" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
 <label>Base URL</label>
 <backend_model>Magento\Config\Model\Config\Backend\Baseurl</backend_model>
 <comment>Specify URL or {{base_url}} placeholder.</comment>
</field>

Then you can find the beforeSave method at \m9agento210\vendor\magento\module-config\Model\Config\Backend\Baseurl.php

public function beforeSave()
{
 $value = $this->getValue();
 try {
 // You can write some validation here.
 } catch (\Magento\Framework\Exception\LocalizedException $e) {
 throw $error;
 }
}

This is an example, you can implement this in your custom module.

Option 2

 <field id="custom_email" translate="label comment" sortOrder="0" type="text" showInDefault="1" showInWebsite="0" showInStore="0">
 <label>Enter Email Id</label>
 <validate>validate-email</validate>
 </field>

Some Important validation classes are

'validate-no-html-tags' => 'HTML tags are not allowed'
'validate-select' => 'Please select an option.'
'required-entry' => 'This is a required field.'
'validate-number' => 'Please enter a valid number in this field.'
'validate-digits' => 'Please use numbers only in this field. Please avoid spaces or other characters such as dots or commas.'
'validate-date' => 'Please enter a valid date.'
'validate-email' => 'Please enter a valid email address. For example [email protected].'
'validate-url' => 'Please enter a valid URL. Protocol is required (http://, https:// or ftp://)'
'validate-not-negative-number' => 'Please enter a number 0 or greater in this field.'
'validate-zero-or-greater' => 'Please enter a number 0 or greater in this field.'
'validate-state' => 'Please select State/Province.'
'validate-cc-number' => 'Please enter a valid credit card number.'
'validate-data' => 'Please use only letters (a-z or A-Z), numbers (0-9) or underscore(_) in this field, first character should be a letter.'

Hope it helps.

• Pankaj Sharma: Thanks Krishna, ie. Okay. is there not any way to validate field directly in system.xml. I just need to add min='1' in my admin XML file ?
• Krishna ijjada: @ Pankaj Sharma, As of my knowledge, there is no direct config validation like min='1' . You can follow the custom validation options added in the answer.
• Pankaj Sharma: Okay fine, if I proceed with option 2. Do you have any idea, how I can create a validation method for my requirement? value should be grater then 0. Remember I am creating a custom model.
• Krishna ijjada: You can simple go with option one by creating custom validation and return response. Please check the core validation once I added in the answer. This may be the quick approach.

Answer 2

Finally, I got Solution for my Question. Here is solution system.xml code:

<field id="uspsintexpress" translate="label" type="text" sortOrder="70" showInDefault="1" showInWebsite="1" showInStore="1">
<label>USPS Int'l Express Days</label>
<validate>validate-greater-than-zero</validate>
</field>