OptionWriter.renderFromMap fails when map key is null [SPR-7024]

[spring-projects-issues]

Shai Yallin opened SPR-7024 and commented

When using a Map as the items values for an OptionWriter-based tag and ommiting the itemValue property (valueProperty is null), OptionWriter still creates BeanWrappers around the map key and values although they are never used.

As a result of that, one is unable to use null as a map key, which may be useful for instance when the map contains enum values as keys and their localized names as values. In this scenario, it may be useful to include null as a map key which represents an empty field value.

affected code:
{{
Object mapKey = entry.getKey();
Object mapValue = entry.getValue();
BeanWrapper mapKeyWrapper = PropertyAccessorFactory.forBeanPropertyAccess(mapKey);
BeanWrapper mapValueWrapper = PropertyAccessorFactory.forBeanPropertyAccess(mapValue);
Object renderValue = (this.valueProperty != null ? mapKeyWrapper.getPropertyValue(this.valueProperty) :
mapKey.toString());
Object renderLabel = (this.labelProperty != null ? mapValueWrapper.getPropertyValue(this.labelProperty) :
mapValue.toString());
renderOption(tagWriter, mapKey, renderValue, renderLabel);
}}

fix suggestion: only create the wrappers if this.valueProperty != null

---

Affects: 3.0.1

Referenced from: commits a614430

[spring-projects-issues]

Juergen Hoeller commented

We'll also have to make the mapKey.toString() and mapValue.toString() code null-safe then, since that would be executed instead of the BeanWrapper calls... I suppose you would rather expect null to turn into an empty String there, i.e. not into "null" or the like?

Juergen

[spring-projects-issues]

Shai Yallin commented

Definitely. As I said, my use case is enums as map keys and their localized names (via a message source) as map values. Such a field is bound to an enum field on the model attribute, so an empty string in the option values should be translated to a null enum value. I hope that the property editor already does that...

[spring-projects-issues]

Juergen Hoeller commented

I've adapted this for 3.0.2 now. This will be available in tonight's 3.0.2 snapshot - feel free to give it an early try if you chance, and let me know whether it works for you.

Juergen