Why is convertRequestParameter protected

[sleroux]

Hi everybody.

I need to access to a GET request parameter.

org.jboss.seam.web.Parameters#convertRequestParameter does exactly what I want. But this method is protected.

So my question: Why is the convertRequestParameter method in org.jboss.seam.web.Parameters protected, whereas in the same time, the convertMultiValueRequestParameter method is public?

Sylvain.

[sleroux]

Ok,

I mis-read the code and thought that the requestParam argument was the name of the parameter. But it's the value.

protected Object convertRequestParameter(String requestParameter,
                                         Class type)

So I will use getRequestParameters+convertMultiValueRequestParameter in something like this:

Map<String,String[]> paramMap = parameters.getRequestParameters();
int my_value parameters.convertMultiValueRequestParameter(paramMap, "my_param", Integer.class);

Maybe this behavior should be encapsuled in a class?

SL

[pmuir]

Sylvain Leroux wrote on Mar 25, 2008 03:10 PM:


Maybe this behavior should be encapsuled in a class?

Huh? It already is, Parameters.

[sleroux]

I wrote class, but I thought more about a missing method for the Parameters class. Let me explain myself:

As far as I understand, I need 2 method calls just to retrieve the value of a parameter. Something like parameters.getRequestParameter("my_param", MyClass.class) sounds definitively more natural...

And if I said that, it was not (only) by laziness: because of those two calls, It's difficult to use the value of a request parameter in an EL expression (like in an action of a jPDL pageflow - that's what I tried to do).

Sylvain.

[pmuir]

We could create getConvertedRequestParameter(String name, Class<?> type) - file a request in JIRA.

[sleroux]

Done: JIRA JBSEAM-2801

---

For now, here's how I resolved this issue by using a custom component in order to access to a request parameter from a jPDL action:

/**
 * Give access to request parameters from EL expressions.
 * 
 * @usage
 * <tt>#{param_helper.getConvertedRequestParameter('paramName', stringClass)}</tt>
 * 
 * @author Sylvain Leroux
 *
 */
@Scope(EVENT)
@Name("param_helper")
public class ParameterHelper {
    Map<String, String[]>           requestParameters;
    org.jboss.seam.web.Parameters     parameters;
    
    @Create
    public void initParameterHelper() {
     parameters = org.jboss.seam.web.Parameters.instance();
     requestParameters = parameters.getRequestParameters();
    }
    
    public Object getConvertedRequestParameter(String name, Class<?> type) {
     return parameters.convertMultiValueRequestParameter(requestParameters, name, type);
    }

    public static ParameterHelper instance()
    {
       return (ParameterHelper) Component.getInstance(ParameterHelper.class, ScopeType.EVENT);
    }

    /**
     * Give access to <tt>String.class</tt> from an EL expression (which cannot access
     * <em>static fields</em>).
     * @return String.class
     */
    @Factory(scope=APPLICATION)
    public Class<String> getStringClass() {
     return String.class;
    }

    /**
     * Give access to <tt>Integer.class</tt> from an EL expression (which cannot access
     * <em>static fields</em>).
     * @return Integer.class
     */
    @Factory(scope=APPLICATION)
    public Class<Integer> getIntegerClass() {
     return Integer.class;
    }
    
    /* ... other class accessors here ... */
}

Please note that getStringClass, getIntegerClass, ... are required since, AFAIK, I cannot access static fields from an EL expression. I certainly should have put those methods in a separate (APPLICATION scoped) component.