Hi! It is simple to reproduce:
Jackson version and jackson-dataformat-xml version: 2.9.8
DTO
@JacksonXmlRootElement(localName = "test")
public class TestResult {
@JacksonXmlProperty(localName = "string")
@JacksonXmlElementWrapper(localName = "strings")
private List<String> strings;
public TestResult() {
}
public List<String> getStrings() {
return strings;
}
public void setStrings(List<String> strings) {
this.strings = strings;
}
}
A test method
void testElementWrapperWithNoElements() throws IOException {
ObjectMapper mapper = new XmlMapper();
String xml = "<test><strings></strings></test>";
TestResult res = mapper.readValue(xml, TestResult.class);
assert res != null && res.getStrings() == null;
}
Expected null value for the collection field but got an exception
com.fasterxml.jackson.databind.exc.MismatchedInputException:
Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING
token
at [Source: (StringReader); line: 1, column: 16] (through reference chain:
com.acme.TestResult["strings"])
at
com.acme.XmlSerializationTest.testElementWrapperWithNoElements(XmlSerializationTest.java:258)
пятница, 12 июля 2019 г., 8:09:37 UTC+3 пользователь Tatu Saloranta написал:
>
> On Wed, Jul 10, 2019 at 4:55 PM Dmitriy Grigoryev <[email protected]
> <javascript:>> wrote:
>
>> Hi!
>> I have the following formatted xml fragment of some service response:
>>
>> ...
>> <items>
>> </items>
>> ...
>>
>>
>> *Note! *There is *linebreak* between start and closing elements.
>>
>> And I have the following corresponding code fragment:
>>
>> @JacksonXmlProperty(localName = "item")
>> @JacksonXmlElementWrapper(localName = "items")
>> private List<Item> items;
>>
>> Why I get the following deserialization error ?
>>
>>
>> Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING
>> token
>>
>> I think that if we have this combination of annotations for a field then it
>> should consider only collection items and nothing else inside the wrapping
>> element.
>>
>> Is it bug or feature ?
>>
>>
> It is difficult to say since you are only including snippets and not the
> whole XML or whole class definition.
> If you include both (or maybe even reproduction), it will be easier to see
> what the problem is.
>
> But the way to troubleshoot things with Jackson XML module is usually to
> reverse the process: see what kind of output you would get for specific
> annotated class, and make that match what you expect as input.
>
> -+ Tatu +-
>
>
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