form:option problem

[matrix]

Hi,
I am using form:option tag to show some option values in Drop Down menu.
While iterating over collection of Entry type objects.(java.util.Map.Entry)

where Entry<Key,Value> is <Integer,Object>.

<c:forEach items="${collection}" var="tmp" >
   <form:option value="${tmp.key}"  label="${tmp.value.desc}"/>
</c:forEach>

it show no value for options.

<option value="">Option Label 1</option>
<option value="">Option Label 2</option>
<option value="">Option Label 3</option>
<option value="">Option Label 4</option>

But in this case.

<c:forEach items="${collection}" var="tmp" >
   <c:out value="${tmp.key}" />:<c:out  value="${tmp.value.desc}"/>
</c:forEach>

Result is OK as expected.

1:Option Label 1
2:Option Label 2
3:Option Label 3
4:Option Label 4

If anybody can explain why it is showing different behavior.

Thanks in advance

[jonnio]

The form option KEY looks for the .toString() method of the key value if the source is a map. You shouldn't need to specify the key or the value if you have implemented the map the way spring wants you to.

[lumpynose]

I didn't know you could do that with a hash map. This is how I got it to work (with spring 2.5 annotations):
controller:

@Controller
@RequestMapping("/post6.zug")
public final class Post6Controller {

(stuff omitted)

    @ModelAttribute("referenceData6")
    public Set<Map.Entry<String, Integer>> referenceData() {
        final Map<String, Integer> map = new HashMap<String, Integer>();

        for (int i = 1; i < 6; i++) {
            final String optionLabel = String.format("option%02d", i);

            map.put(optionLabel, i);
        }

        log.debug("map: {}", map);

        return (map.entrySet());
    }

(stuff omitted) 

jsp:

(stuff omitted)
                <form:select path="selectPath">
                    <form:option label="select an item" value="" />
                    <form:options
                        items="${referenceData6}"
                        itemValue="value"
                        itemLabel="key"
                    />
                </form:select>
(stuff omitted) 

generated html:

                <select id="selectPath" name="selectPath">
                    <option value="">select an item</option>
                    <option value="5">option05</option><option value="3">option03</option><option value="4">option04</option><option value="1">option01</option><option value="2" selected="selected">option02</option>
                </select> 

[lumpynose]

I'm not sure, but this may be more like what you're doing, but I'm not using a HashMap:

    @ModelAttribute("referenceData5")
    public ReferenceData5 referenceData() {
        final Collection<FormOption> formOptions = new ArrayList<FormOption>();

        for (int i = 1; i < 6; i++) {
            final String optionLabel = String.format("option%02d", i);

            final FormOption formOption = new FormOption(optionLabel, i);

            formOptions.add(formOption);
        }

        log.debug("formOptions: {}", formOptions);

        final ReferenceData5 referenceData5 =
            new ReferenceData5(formOptions);

        return (referenceData5);
    } 

public final class ReferenceData5 {
    private final Collection<FormOption> formOptions;

    ...

    public Collection<FormOption> getFormOptions() {
        return (formOptions);
    } 

public final class FormOption {
    private final String selectLabel;
    private final int selectValue;

    public FormOption(final String _selectLabel, final int _selectValue) {
        this.selectLabel = _selectLabel;
        this.selectValue = _selectValue;
    }

(usual getters and setters omitted) 

                <form:select path="selectPath">
                    <form:option label="select an item" value="" />

                    <form:options
                        items="${referenceData5.formOptions}"
                        itemValue="selectValue"
                        itemLabel="selectLabel"
                    />
                </form:select> 

[matrix]

Thanks a lot...

[ysbelman]

Examples above helped me with my use-case... there's another example with enum type.

enum type declared with getLongName(), getKey() methods that will be used by the <form> tag:

public enum LandZoningType{
	CONSERVATION_PASSIVE_RECREATION("CP", "Conservation/Passive Recreation"), 
	SINGLE_FAMILITY_RESIDENTIAL_R1("R1", "Single Family Residential, large lot size"),
	SINGLE_FAMILITY_RESIDENTIAL_R2("R2", "Single Family Residential, smaller than R-1"),
	
	final public String longName;
	final public String code;
	
	public String getLongName(){
		return longName;
	}
	
	public String getCode(){
		return code;
	}
	
	public String getKey(){
		return toString();
	}
		
	LandZoningType(String code, String longName){
		this.code = code;
		this.longName = longName;
	}
}

service layer creating a collection of enum type instances:

public  Collection<LandZoningType> getLandZoneTypes(){
	final Collection<LandZoningType> types = new ArrayList<LandZoningType>();
	for (LandZoningType st : LandZoningType.values()){
		types.add(st);
	}
	return types; 
}

jsp:

<form:select path="landZoneType" items="${landZoneTypes}" itemValue="key" itemLabel="longName"/>

[lumpynose]

Nice.

Nothing's more fun that optimizing someone else's code; could you do this instead

private final Set<LandZoningType> zoningType = EnumSet.allOf(LandZoningType.class);

public  Collection<LandZoningType> getLandZoneTypes(){
    return(zoningType);
}

Or would it be an EnumMap?

private final Map<LandZoningType> zoningTypes = new EnumMap(LandZoningType.class);
...
public  Collection<LandZoningType> getLandZoneTypes(){
    return(zoningTypes);
}

I can't remember if I've ever used an EnumMap so I don't remember how to use them so the above (either of them) may not compile (the Map is obviously missing something). And I'm not sure if the return for the latter one should instead be

    return(zoningTypes.entrySet());

Enums aren't used enough as far as I'm concerned.