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BAEL-5830 Add code for setting default values for null fields with Jackson (#14265)

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sam-gardner 2023-06-19 16:15:16 +01:00 committed by GitHub
parent 4ad0de6842
commit 9bbd08c6a8
4 changed files with 114 additions and 0 deletions
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30
jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/defaultvalues/JsonSetterDefaultValue.java Normal file
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package com.baeldung.jackson.defaultvalues;
import com.fasterxml.jackson.annotation.JsonSetter;
public class JsonSetterDefaultValue {
private String required;
private String optional = "valueIfMissingEntirely";
@JsonSetter("optional")
public void setOptional(String optional){
if(optional == null){
this.optional = "valueIfNull";
}
}
public String getRequired() {
return required;
}
public String getOptional() {
return optional;
}
@Override
public String toString() {
return "NonAnnotatedDefaultValue{" + "required='" + required + '\'' + ", optional='" + optional + '\'' + '}';
}
}

20
jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/defaultvalues/NonAnnotatedDefaultValue.java Normal file
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package com.baeldung.jackson.defaultvalues;
public class NonAnnotatedDefaultValue {
private String required;
private String optional = "defaultValue";
public String getRequired() {
return required;
}
public String getOptional() {
return optional;
}
@Override
public String toString() {
return "NonAnnotatedDefaultValue{" + "required='" + required + '\'' + ", optional='" + optional + '\'' + '}';
}
}

27
jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/defaultvalues/NullsSkipDefaultValue.java Normal file
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package com.baeldung.jackson.defaultvalues;
import com.fasterxml.jackson.annotation.JsonSetter;
import com.fasterxml.jackson.annotation.Nulls;
public class NullsSkipDefaultValue {
private String required;
@JsonSetter(nulls = Nulls.SKIP)
private String optional = "defaultValue";
public void setOptional(String optional){}
public String getRequired() {
return required;
}
public String getOptional() {
return optional;
}
@Override
public String toString() {
return "NonAnnotatedDefaultValue{" + "required='" + required + '\'' + ", optional='" + optional + '\'' + '}';
}
}

37
jackson-modules/jackson-core/src/test/java/com/baeldung/jackson/defaultvalues/DefaultValuesUnitTest.java Normal file
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package com.baeldung.jackson.defaultvalues;
import org.junit.Test;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class DefaultValuesUnitTest {
@Test
public void givenAClassWithADefaultValue_whenReadingJsonWithoutOptionalValue_thenExpectDefaultValueInResult() throws JsonProcessingException {
String noOptionalField = "{\"required\": \"value\"}";
ObjectMapper objectMapper = new ObjectMapper();
NonAnnotatedDefaultValue createdObject = objectMapper.readValue(noOptionalField, NonAnnotatedDefaultValue.class);
assert(createdObject.getRequired()).equals("value");
assert(createdObject.getOptional()).equals("defaultValue");
}
@Test
public void givenAClassWithAJsonSetter_whenReadingJsonWithNullOptionalValue_thenExpectDefaultValueInResult() throws JsonProcessingException {
String nullOptionalField = "{\"required\": \"value\", \"optional\": null}";
ObjectMapper objectMapper = new ObjectMapper();
JsonSetterDefaultValue createdObject = objectMapper.readValue(nullOptionalField, JsonSetterDefaultValue.class);
assert(createdObject.getRequired()).equals("value");
assert(createdObject.getOptional()).equals("valueIfNull");
}
@Test
public void givenAClassWithAJsonSetterNullsSkip_whenReadingJsonWithNullOptionalValue_thenExpectDefaultValueInResult() throws JsonProcessingException {
String nullOptionalField = "{\"required\": \"value\", \"optional\": null}";
ObjectMapper objectMapper = new ObjectMapper();
NullsSkipDefaultValue createdObject = objectMapper.readValue(nullOptionalField, NullsSkipDefaultValue.class);
assert(createdObject.getRequired()).equals("value");
assert(createdObject.getOptional()).equals("defaultValue");
}
}