Re: Checkbox (CORRECTION)

[don clasen <dc...@yahoo.com>]

Sorry the statement regarding the checkbox value in
the HTTP Request in my previous response:

"...and does not include it if the checkbox is
checked..."

should have been

"...and does not include it if the checkbox is NOT
checked..."


--- don clasen <dc...@yahoo.com> wrote:
> See comments below.
>
> --- Ralph Schaer <sc...@ess.ch> wrote:
> > Nightly Build 2000/06/13
> >
> > >The initial thinking was that a <struts:checkbox>
> > would represent the value
> > of a
> > >single boolean property in your bean.
> >
> > OK. Now I understand. But there are still a few
> > problems.
> >
> >
> > example 1
> > ---------
> >
> > JSP:  <struts:checkbox
> >
> name="administrator">administrator</struts:checkbox>
> >
> > Source: TestForm implements ActionForm
> >
> >   private boolean admin = false;
> >
> >   public boolean getAdministrator() {
> >     return admin;
> >   }
> >
> >   public void setAdministrator(boolean admin) {
> >     this.admin = admin;
> >   }
> >
> > The user select the checkbox and press the submit
> > button
> > The browser sends the following request to the
> > server:
> >
>
http://localhost:8080/test.do?submit=OK&administrator=on
> >
> > The admin property in TestForm is still false
> > because "on" is not mapped to
> > true
> >
> > This is easy to fix. After line 125 in
> > BeanUtils.java add the follwing code:
> >      else if (value.equalsIgnoreCase("on"))
> >         return (new Boolean(true));
> >
> >
> > With this fix example 1 is working
> >
> >
> > example 2
> > ---------
> >
> > JSP: same as example 1
> > Source: private boolean admin = true;
> >
> > The checkbox is now selected. The user DESELECT
> the
> > checkbox and press the
> > submit button
> > The browser sends the follwing request to the
> > server:
> > http://localhost:8080/test.do?submit=OK
> >
> > The admin property is still true because there is
> no
> > "administrator" in the
> > query string.
> > Thats very annoying that the browser doesn't send
> > something like
> > "administrator=off"
> >
> > I have no idea how to handle this case.
> >
> >
>
>
>
> I don't understand why we don't just map any
> non-null
> value to true and any null value to false. The
> browser
> includes the checkbox in the request parameters only
> if it is checked (thus request.getParameter() will
> not
> be null) and does not include it if the checkbox is
> checked (and request.getParamter() will return
> null).
>
> With a checkbox, the actual value is irrelevant in
> the
> incoming request, it's simply either included (on
> (not
> null) ==> true) or not included (off (null) ==>
> false). If you're depending on the actal value, you
> should be using a radio button control.
>
>
> >
> > example 3a
> > ----------
> >
> > more than one checkbox.
> > with existing tag
> >
> > JSP: <struts:checkbox
> > name="blue">blue</struts:checkbox>
> >      <struts:checkbox
> > name="red">red</struts:checkbox>
> >      <struts:checkbox
> > name="green">green</struts:checkbox>
> >      <struts:checkbox
> > name="yellow">yellow</struts:checkbox>
> >      <struts:checkbox
> > name="black">black</struts:checkbox>
> >
> > Source:
> >   private boolean blue = false;
> >
> >   public boolean getBlue() {
> >     return blue;
> >   }
> >
> >   public void setBlue(boolean blue) {
> >     this.admin = blue;
> >   }
> >
> >   //Same for red, green, yellow, black
> >
> > Disadvantag: Every checkbox needs a property and a
> > get/set method. Adding a
> > new checkbox to the jsp page
> >              needs a code change in the Form
> >
>
>
> This example screams out "Use a radio button named
> color, not a checkbox".
>
>
>
> >
> > example 3b
> > ----------
> >
> > My suggestion: mapping checkbox to String[]
> >
> > JSP: <struts:checkbox
> > name="colour">blue</struts:checkbox>
> >      <struts:checkbox
> > name="colour">red</struts:checkbox>
> >      <struts:checkbox
> > name="colour">green</struts:checkbox>
> >      <struts:checkbox
> > name="colour">yellow</struts:checkbox>
> >      <struts:checkbox
> > name="colour">black</struts:checkbox>
> >
> > Source:
> >   private String[] colour = null;
> >
> >   public String[] getColour() {
> >     return colour;
> >   }
> >
> >   public void setColour(String[] colour) {
> >     this.colour = colour;
> >   }
> >
> > This is the way JSP maps checkboxes to java with
> the
> > setProperty tag (<jsp:setProperty name="test"
> > property="*"/>)
> >
> >
> > !!Also this approach has the problem mentioned in
> > example 2!!!
> >
> >
>
>
> See my comment on the last example. If a page
> developer uses checkboxes as in this example instead
> of radios, I'm not sure you'd even get consistent
> results across browsers. I know IE doesn't permit
> multiple controls with the same name (outside of
> radio
> buttons). Also, you'd have to include a JavaScript
> validation function in onClick for all of these that
> would clear the others when one was checked. THe
> browser does this for you with radios.
>
>
>
>
>
> > >It might end up making the most sense to create a
> > new tag for this purpose,
>
=== message truncated ===



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