Add new field in system.xml that allows only numbers

Question

I want to add a new field in system.xml which allows only numeric values.

How can I validate that?

Here is my code

<config>
    <sections>
        <newsletter translate="label" module="newsletter">
            <label>Newsletter</label>
            <tab>phone</tab>
            <frontend_type>text</frontend_type>
            <sort_order>110</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>1</show_in_website>
            <show_in_store>1</show_in_store>
       </newsletter>
  </sections>
</config>

Answer 1

Usually in your file System.xml, if you needed to add a restriction to a field you have to add embedded validators into your file. There are numerous validators like

• validate-select
• required-entry
• validate-number
• validate-digits

and many more

In this case, you need to add validate-number like

<config>
        <sections>
            <newsletter translate="label" module="newsletter">
                <label>Newsletter</label>
                <tab>phone</tab>
                <frontend_type>text</frontend_type>
                <sort_order>110</sort_order>
                <show_in_default>1</show_in_default>
                <show_in_website>1</show_in_website>
                <show_in_store>1</show_in_store>
                <validate>validate-number</validate>
         </newsletter>
      </sections>
    </config>

That's it.