Re: [Springframework-developer] Small change in DataBinder's bind() behavior

[<jue...@we...>]

Dmitriy,
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I wouldn't build generic string trimming capability into DataBinder =
itself: We already have StringTrimmerEditor for this, which can be =
registered as custom editor.
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That said, I do see your use case for required fields. What about =
redefining required fields to accept empty strings? I.e. to change the =
required check as follows:
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  if (pv =3D=3D null || pv.getValue() =3D=3D null ||
      (pv.getValue() instanceof String && !StringUtils.hasText((String) =
pv.getValue()))) {

I consider redefining the required check like this, without an extra =
config property. IMO, this is sensible for a required check anyway, from =
a semantic point of view...
=20
Juergen
=20

________________________________

Von: spr...@li... im Auftrag =
von Dmitriy Kopylenko
Gesendet: Di 05.10.2004 05:00
An: spr...@li...
Betreff: [Springframework-developer] Small change in DataBinder's bind() =
behavior


Juergen,

I was browsing the source for DataBinder and co. and playing with =
"required fields" functionality and DataBinder's tests and I've noticed =
the following - it's not possible to configure the DataBinder to trim =
the unwanted spaces from the required fields. Consider the following =
test case:

TestBean alef =3D new TestBean();
DataBinder binder =3D new DataBinder(alef, "person");
binder.setRequiredFields(new String[]{"name", "touchy", "date"});

MutablePropertyValues pvs =3D new MutablePropertyValues();
pvs.addPropertyValue(new PropertyValue("touchy", "    "));
pvs.addPropertyValue(new PropertyValue("name", null));

binder.bind(pvs);

BindException ex =3D binder.getErrors();
assertEquals("Wrong amount of errors", 3, ex.getErrorCount());

This will fail because it will not recognize required "touchy" field as =
not being present because it contains spaces. It would really be nice to =
control trimming of such "accidentally set spaces" for required fields =
so the bind() method could then treat them as "missing required field".

I've added the flag to DataBinder ("trimSpacesInStringFields") and small =
piece of logic in DataBinder.bind(PropertyValues):

// check for missing fields
        if (this.requiredFields !=3D null) {
            for (int i =3D 0; i < this.requiredFields.length; i++) {
                PropertyValue pv =3D =
pvs.getPropertyValue(this.requiredFields[i]);
               =20
                //This is what I added
                if(this.trimSpacesInStringFields && pv !=3D null && =
pv.getValue() !=3D null && pv.getValue() instanceof String) {
                    pv =3D new PropertyValue(pv.getName(), =
((String)pv.getValue()).trim());
                }
               =20
                if (pv =3D=3D null || "".equals(pv.getValue()) || =
pv.getValue() =3D=3D null) {
                    // create field error with code "required"
                    String field =3D this.requiredFields[i];
                    this.errors.addError(
                            new FieldError(this.errors.getObjectName(), =
field, "", true,
                            =
this.errors.resolveMessageCodes(MISSING_FIELD_ERROR_CODE, field),
                            getArgumentsForBindingError(field), "Field =
'" + field + "' is required"));
                }
            }
        }
...// the rest is omitted

Then by modifying test case a little, it works perfectly:

        TestBean alef =3D new TestBean();

        DataBinder binder =3D new DataBinder(alef, "person");
        binder.setRequiredFields(new String[]{"name", "touchy", =
"date"});
       =20
        //Set the new flag
        binder.setTrimSpacesInStringFields(true);

        MutablePropertyValues pvs =3D new MutablePropertyValues();
        pvs.addPropertyValue(new PropertyValue("touchy", "    "));
        pvs.addPropertyValue(new PropertyValue("name", null));

        binder.bind(pvs);

        BindException ex =3D binder.getErrors();
        System.out.println(alef.getTouchy().length());
        System.out.println(ex);
        assertEquals("Wrong amount of errors", 3, ex.getErrorCount());

I think it would be a very handy feature (for us at least), unless I =
missed something fundamental.

Thoughts?

Regards,
Dmitriy.