How to load a java.util.Set with snakeYAML


I try to load the following yaml sequence :

- Person(paul): firstName: Paul lastName: Lumbergh children : - Person(bill) - Person(jane)

which i tried to load in the following bean :

public class Person { private long id; private String firstName; private String lastName; private Person father; private Set<Person> children; }

I got this error which is due to the fact that snakeYaml load my sequence in a java.util.List instead of java.util.Set.

Is it a way to force snakeYAML to load a sequence in a java.util.Set ?

org.yaml.snakeyaml.error.YAMLException: org.yaml.snakeyaml.error.YAMLException: Cannot set property='children' with value='[Person [firstName=Bill, secondName=Lumbergh], Person [firstName=Jane, secondName=Lumbergh]]' (class java.util.ArrayList) in Person [firstName=Paul, secondName=Lumbergh] at org.yaml.snakeyaml.extensions.compactnotation.CompactConstructor$ConstructCompactObject.construct(CompactConstructor.java:163) at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:183) at org.yaml.snakeyaml.constructor.BaseConstructor.constructSequenceStep2(BaseConstructor.java:277) at org.yaml.snakeyaml.constructor.BaseConstructor.constructSequence(BaseConstructor.java:248) at org.yaml.snakeyaml.constructor.SafeConstructor$ConstructYamlSeq.construct(SafeConstructor.java:440) at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:183) at org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:142) at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:128) at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:480) at org.yaml.snakeyaml.Yaml.load(Yaml.java:411) at com.pearson.fixy.Fixy.loadEntities(Fixy.java:105) at com.pearson.fixy.Fixy.load(Fixy.java:126) at com.dvidea.TestFixy.test(TestFixy.java:24) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)


According to the yaml <a href="http://yaml.org/type/set.html" rel="nofollow">specification</a> the set syntax is the following one :

- Person(paul): firstName: Paul lastName: Lumbergh children : !!set ? Person(bill) ? Person(jane) –


You force SnakeYAML to use List instead of Set. Sets have different representation in YAML: <a href="http://yaml.org/type/set.html" rel="nofollow">http://yaml.org/type/set.html</a>

You can change the YAML document or instruct SnakeYAML to use sets instead of lists. You may need to look <a href="http://code.google.com/p/snakeyaml/source/browse/src/test/java/org/yaml/snakeyaml/issues/issue73/SetAsSequenceTest.java" rel="nofollow">in tests</a>


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