DD4T 2.0 Java Spring MVC: How to fetch the component field value when it has multiple keywords as its values?

Question

In ViewModel class I am not able to fetch the field values; the field has multiple keywords as its value (say keyword1 and keyword2). Below is the snapshot of the

In ViewModel class I tried to use variable type as KeywordField as suggested in http://blog.trivident.com/viewmodel-functionality-in-dd4t-2-0-for-java-part-ii-creating-viewmodels/ but it gives below Exception:

java.lang.IllegalArgumentException: Can not set org.dd4t.contentmodel.impl.KeywordField field com.web.cms.model.PackageBundle.bonusItem to org.dd4t.contentmodel.impl.KeywordImpl
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
    at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
    at java.lang.reflect.Field.set(Field.java:764)
    at org.dd4t.databind.builder.AbstractModelConverter.setFieldValueOnField(AbstractModelConverter.java:94)
    at org.dd4t.databind.builder.AbstractModelConverter.setFieldValue(AbstractModelConverter.java:72)
    at org.dd4t.databind.builder.json.JsonModelConverter.deserializeGeneric(JsonModelConverter.java:296)
    at org.dd4t.databind.builder.json.JsonModelConverter.buildField(JsonModelConverter.java:208)
    at org.dd4t.databind.builder.json.JsonModelConverter.buildModelProperties(JsonModelConverter.java:116)
    at org.dd4t.databind.builder.json.JsonModelConverter.convertSource(JsonModelConverter.java:95)
    at org.dd4t.databind.builder.json.JsonDataBinder.buildModel(JsonDataBinder.java:175)

Answer 1

First of all, your Keyword Json structure should look something like this:

"Color" : {
    "Name" : "Color",
    "Value" : "Blue",
    "Values" : [ "Blue", "Red", "White" ],
    "NumericValues" : [ ],
    "DateTimeValues" : [ ],
    "LinkedComponentValues" : [ ],
    "FieldType" : 3,
    "CategoryName" : "Colors",
    "CategoryId" : "tcm:7-1020-512",
    "XPath" : "tcm:Metadata/custom:Metadata/custom:Color",
    "KeywordValues" : [ {
      "Description" : "",
      "Key" : "",
      "TaxonomyId" : "tcm:7-1020-512",
      "Path" : "\\Colors\\Blue",
      "ParentKeywords" : [ ],
      "MetadataFields" : { },
      "Id" : "tcm:7-2116-1024",
      "Title" : "Blue"
    }, {
      "Description" : "",
      "Key" : "",
      "TaxonomyId" : "tcm:7-1020-512",
      "Path" : "\\Colors\\Red",
      "ParentKeywords" : [ ],
      "MetadataFields" : { },
      "Id" : "tcm:7-2114-1024",
      "Title" : "Red"
    }, {
      "Description" : "",
      "Key" : "",
      "TaxonomyId" : "tcm:7-1020-512",
      "Path" : "\\Colors\\White",
      "ParentKeywords" : [ ],
      "MetadataFields" : { },
      "Id" : "tcm:7-2115-1024",
      "Title" : "White"
    } ]

If this is not OK, then you need to check your field type in the Schema and check with which version of the DD4T TBBs you are rendering content.

If that is OK, then the next step is to define the property correctly in your view model. Since you are adding multiple Keywords, the field is multi-value, which means you must enclose the individual keywords in a List:

@ViewModelProperty(entityFieldName = "Color")
private List<Keyword> color;

public List<Keyword> getColor () {
    return color;
}

public void setColor (final List<Keyword> color) {
    this.color = color;
}

If you debug this, then the actual values come out as as List of KeywordImpls:

Subsequently, you can then use the view model in your view as follows:

<c:if test="${!empty event.color}">
    <c:forEach items="${event.color}" var="colorKeyword">
        <c:out value="${colorKeyword.title}" />
    </c:forEach>
</c:if>