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Apache Struts 2 Documentation
Debugging
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Modern IDEs provide excellent support for debugging. In addition, the framework provides support for inspecting framework-specific objects at runtime.

The Debugging Interceptor provides three debugging modes to provide insight into the data behind the page. The `xml` mode formats relevant framework objects as an XML document. The `console` mode provides a OGNL command line that accepts entry of runtime expressions, and the `browser` mode adds an interactive page that display objects from the Value Stack.

To use the debugging, first be sure that `struts.devMode` is set to `true` is enabled through the struts.properties file or `struts.xml` file, like:

    <constant name="struts.devMode" value="true" />

Then, whenever a page needs debugging, add `?debug=xml` or `?debug=console` or `?debug=browser` to the URL.

    - <debug>
      <parameters />
    - <context>
    - <struts.actionMapping>
      <class>class org.apache.struts2.dispatcher.mapper.ActionMapping</class>
      <name>showcase</name>
      <namespace>/</namespace>
      </struts.actionMapping>
      <attr />
      <__devMode>true</__devMode>
      <report.conversion.errors>false</report.conversion.errors>
      </context>
      <request />
      <session />
    - <valueStack>
    - <value>
      <actionErrors />
      <actionMessages />
      <class>class com.opensymphony.xwork2.ActionSupport</class>
      <errorMessages />
      <errors />
      <fieldErrors />
    - <locale>
      <ISO3Country>USA</ISO3Country>
      <ISO3Language>eng</ISO3Language>
      <class>class java.util.Locale</class>
      <country>US</country>
      <displayCountry>United States</displayCountry>
      <displayLanguage>English</displayLanguage>
      <displayName>English (United States)</displayName>
      <displayVariant />
      <language>en</language>
      <variant />
      </locale>
      </value>
    - <value>
      <class>class com.opensymphony.xwork2.DefaultTextProvider</class>
      </value>
      </valueStack>
      </debug>

For `?debug=xml` use Internet Explorer or an IE tab in FireFox

For `?debug=console` you may need to relax any popup blockers

## Next: Development Mode