Magento: Add default value to System Configuration Option fields

This article shows how to add default value to any system configuration option fields. System configuration option fields means those options under System -> Configuration.

Suppose, you have the following system.xml file. System.xml file is necessary to add admin configuration options.

system.xml

<?xml version="1.0" encoding="UTF-8"?>
    <config>
       <sections>         
    		<mysection translate="label" module="mymodule">
    			<label>My Section</label>
    			<tab>catalog</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> 
    			<groups>
    				<mygroup translate="label" module="mymodule">
    					<label>My Group</label>
    					<frontend_type>text</frontend_type>
    					<sort_order>99</sort_order>
    					<show_in_default>1</show_in_default>
    					<show_in_website>1</show_in_website>
    					<show_in_store>1</show_in_store>
    					<fields>
    						<myfield translate="label comment">
    							<label>My Field</label>							
    							<frontend_type>text</frontend_type>
    							<sort_order>1</sort_order>
    							<show_in_default>1</show_in_default>
    							<show_in_website>1</show_in_website>
    							<show_in_store>1</show_in_store>
    						</myfield>						
    					</fields>
    				</mygroup>
    			</groups>			
    		</mysection>			
        </sections>
    </config>

Now, to add default value to the admin configuration options, you need to write the following in config.xml file of your module. The should be inside config node.

config.xml

    <default>
    	<mysection>
    		<mygroup>                
    			<myfield>My Default Value</myfield>			
    		</mygroup>		
    	</mysection>
    </default>

Hope this helps. Thanks.