[英]Jackson XML deserialization of abstract type results in fields with null values
當嘗試將 XML 反序列化為擴展抽象基 class 的 object 時,我看到引用列表包含預期數量的元素,但這些對象上的所有字段都是 null。
僅當我為抽象 class 創建一個 XML 讀取器時才會發生這種情況。如果我直接反序列化為具體實現,則所有字段都具有預期值。
我在下面添加了最低限度的工作示例
預期為 output(作為 json 以提高可讀性)
{
"References": [ { "id": "1", "Type": "Secondary Image" } ]
}
實際 output(作為 json 以提高可讀性)
{
"References": [ { "id": null, "Type": null } ]
}
測試數據
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Foo TypeID="ConcreteA">
<Reference ID="1" Type="Secondary Image">
<Values/>
</Reference>
</Foo>
摘要基地 class
@JsonIgnoreProperties(ignoreUnknown = true)
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "TypeID", visible = true)
@JsonSubTypes({
@JsonSubTypes.Type(value = ConcreteClassA.class, name = "ConcreteA")
})
public abstract class AbstractBase {
@JacksonXmlProperty(localName = "TypeID", isAttribute = true)
private String typeId;
@JsonIgnore
private List<Reference> references = new ArrayList<>();
@JacksonXmlElementWrapper(useWrapping = false)
@JacksonXmlProperty(localName = "Reference")
public List<Reference> getReferences() {
return references;
}
@JsonSetter
public AbstractBase setReferences(List<Reference> references) {
this.references.addAll(references);
return this;
}
}
具體實施
public class ConcreteClassA extends AbstractBase {}
測試用例
public class DeserializationTest {
@Test
public void deserializedAbstractClass_fieldsShouldNotBeNull() throws JsonProcessingException {
var mapper = new XmlMapper()
.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true)
.deactivateDefaultTyping()
.registerModule(new JacksonXmlModule());
var xmlData = readTestData();
var reader = mapper.readerFor(AbstractBase.class);
var deserializedObject = reader.readValue(xmlData);
assert(deserializedObject instanceof ConcreteClassA);
var concreteClassA = (ConcreteClassA) deserializedObject;
assert(concreteClassA.getReferences().get(0).getId() != null);
}
@Test
public void deserializedConcreteClass_fieldsShouldNotBeNull() throws JsonProcessingException {
var mapper = new XmlMapper()
.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true)
.configure(MapperFeature.USE_BASE_TYPE_AS_DEFAULT_IMPL, true)
.registerModule(new JacksonXmlModule());
var xmlData = readTestData();
var reader = mapper.readerFor(ConcreteClassA.class);
var deserializedObject = reader.readValue(xmlData);
assert(deserializedObject instanceof ConcreteClassA);
var concreteClassA = (ConcreteClassA) deserializedObject;
assert(concreteClassA.getReferences().get(0).getId() != null);
}
private String readTestData() {
try {
var datafile = getClass().getClassLoader().getResource("TestData.xml");
return Files.lines(Paths.get(datafile.toURI())).collect(Collectors.joining());
} catch (Exception e) { return ""; }
}
}
事實證明,我已經設法解決了多個問題。
此問題已通過升級到 2.12 得到解決,這意味着不再需要執行此操作來處理展開的元素。
我通過讓 setter 接受單個元素,然后將其添加到列表中來解決這個問題
@JsonSetter(value = "Reference")
public AbstractBase setReferences(Reference reference) {
this.references.add(references);
return this;
}
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