What is the difference between JsonIgnore
on Field vs JsonIgnore
on a getter of a field in Jackson?
@JsonIgnore
annotation is used to ignore fields from de-serialization and serialization, it can be put directly on the instance member or on its getter or its setter. The application of the annotation in any of these 3 points, leads to the total exclusion of the property from both the serialization and de-serialization processes (and this applies starting from Jackson 1.9; the version used in these examples is Jackson 2.4.3).
Note: Before version 1.9, this annotation worked purely on method-by-method (or field-by-field) basis; annotation on one method or field did not imply ignoring other methods or fields
Example
import java.io.IOException;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
class MyTestClass {
private long id;
private String name;
private String notInterstingMember;
private int anotherMember;
private int forgetThisField;
public long getId() {
return this.id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
@JsonIgnore
public String getNotInterstingMember() {
return this.notInterstingMember;
}
public void setNotInterstingMember(String notInterstingMember) {
this.notInterstingMember = notInterstingMember;
}
public int getAnotherMember() {
return this.anotherMember;
}
public void setAnotherMember(int anotherMember) {
this.anotherMember = anotherMember;
}
public int getForgetThisField() {
return this.forgetThisField;
}
@JsonIgnore
public void setForgetThisField(int forgetThisField) {
this.forgetThisField = forgetThisField;
}
@Override
public String toString() {
return "MyTestClass [" + this.id + " , " + this.name + ", " + this.notInterstingMember + ", " + this.anotherMember + ", " + this.forgetThisField + "]";
}
}
Output:
{"id":1,"name":"Test program","anotherMember":100}
MyTestClass [1 , Test program, null, 100, 0]
But still it is possible to change this behavior and make it asymmetric, for example to exclude a property only from the deserialization using the @JsonIgnore
annotation together with another annotation called @JsonProperty.