Unable to serialize top-level Java8 Stream #302
Comments
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Hmmh. Yes, so the work-around(s) used for It'd be nice to figure out something more general for iterable types (since they are not quite what |
cowtowncoder
added
2.10
good first issue
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Realized that support probably requires upgrade of JDK baseline for XML module to be Java 8 -- something that is probably reasonable for 2.11, but can not be done in a patch for 2.10. |
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At this point Java 8 requirement is no longer blocker, fwtw. |
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May I ask what the expected behavior is here? Serialization of both Iterable and Stream interfaces types just like how Collection works? |
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@JooHyukKim I would expect that Streams should be treated similarly to an Iterable - like a Collection but ideally without pulling the full Iterable or Stream into memory at one time. |
@pjfanning Hmm, what I can think of, to acheive the goal here is to obtain an instance of By using iterator, we can
What do you think? |
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Feels like the TypeUtil method should be changed to something like Or it might be possible to get access to the I would suggest adding the broken test cases and seeing if the first approach above is enough to fix it. |
I did try exactly that with |
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ModificationTypeUtil : public static boolean isIndexedType(Class<?> cls)
{
return (cls.isArray() && cls != byte[].class && cls != char[].class)
|| Collection.class.isAssignableFrom(cls) || Iterator.class.isAssignableFrom(cls) || Stream.class.isAssignableFrom(cls);
}Used Test case :
public void testElement() throws JsonProcessingException {
List<String> list = new ArrayList<>();
list.add("a");
list.add("b");
assertEquals("<ArrayList><item>a</item><item>b</item></ArrayList>",
OBJECT_MAPPER.writeValueAsString(list));
}
public void testElem() throws JsonProcessingException {
List<String> list = new ArrayList<>();
list.add("a");
list.add("b");
assertEquals("<Itr><item>a</item><item>b</item></Itr>",
OBJECT_MAPPER.writeValueAsString(list.iterator()));
}
public void testopLevelTwoElements() throws JsonProcessingException {
assertEquals("<Adapter><item>a</item><item>b</item></Adapter>",
OBJECT_MAPPER.writeValueAsString(Stream.of("a", "b").iterator()));
}
public void testTopLevelTwoElements() throws JsonProcessingException {
OBJECT_MAPPER.writeValueAsString(Stream.of("a", "b"));
}Direct Stream serialization Error messageFurther works (if agreed, I will push through)
@pjfanning May I ask for you thoughts? |
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use Iterable instead of Collection - Collection is a subclass of Iterable |
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Did you register the Jdk8Module in your Stream test? |
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@pjfanning no, just plain init. |
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jackson needs Jdk8Module to support Streams - see https://github.com/FasterXML/jackson-modules-java8 |
Hmm, using |
@pjfanning Oh, thank you! 🙏🏼🙏🏼 I missed to consider backward compatibility and just simply thought it would all work since baseline jdk is raised to 8. |
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I will try to tidy up everything that has come up in convos from this issue and #329, then try to come up with something. |
cowtowncoder
added
2.16
A
Streamnested in another object is serialized using a value wrapper just as a collection or array, serializing aStreamdirectly fails when more than one element is available as it tries to write a second root. If the Stream emits only a single element serialization works but without wrapping:The root element name is
Headfor Stream serialization as it's determined from the actual class nameReferencePipeline$Head.The cause lies in
TypeUtil.isIndexedType(Class<?>)which just checks for Arrays and Collections and only if this returns true, a field name is written (and _nextName set).It works for the nested Stream as
_nextNameis set due to the Stream being written as a field (multiple times).The text was updated successfully, but these errors were encountered: