JPA - Converter class is not being invoked as expected - spring

Question

I cannot figure out why my converter class is not being called. I have the following Entity class:
import org.springframework.validation.annotation.Validated;
import javax.persistence.Column;
import javax.persistence.Convert;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.util.List;
#Entity
#Validated
#Table(name = "c_mark", schema="common")
public class CMark {
#Id
#Column(name = "c_mark_id")
private String id;
#Column(name = "cl_fk")
private String cFk;
#Column(name = "s_con")
#Convert(converter = StringListConverterCommaDelim.class)
private List<String> sCon;
#Override
public String toString() {
return "ClassificationMarking{" +
"id='" + id + '\'' +
", cFk='" + cFk + '\'' +
", s_con='" + s_con + '\'' +
'}';
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getCFk() {
return cFk;
}
public void setCFk(String cFk) {
this.cFk = cFk;
}
public List<String> getSCon() {
return sCon;
}
public void setSCon(List<String> sCon) {
this.sCon = sCon;
}
}
Here is the converter class:
import javax.persistence.AttributeConverter;
import javax.persistence.Converter;
import java.util.Arrays;
import java.util.List;
import static java.util.Collections.emptyList;
#Converter
public class StringListConverterCommaDelim implements AttributeConverter<List<String>, String>
{
private static final String SPLIT_CHAR = ",";
#Override
public String convertToDatabaseColumn(List<String> stringList) {
return stringList != null ? String.join(SPLIT_CHAR, stringList) : "";
}
#Override
public List<String> convertToEntityAttribute(String string) {
return string != null ? Arrays.asList(string.split(SPLIT_CHAR)) : emptyList();
}
}
Here is the repo interface that defines the insert method:
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
public interface CMarkRepository extends JpaRepository <ClassificationMarking, String> {
#Transactional
#Modifying
#Query(value = "INSERT INTO c_mark(c_fk, s_con) " +
"values(:c_fk, :s_con)", nativeQuery = true)
int insertCMark(#Param("c_fk") String c_fk, #Param("s_con") String s_con);
}
, and finally the method that invokes the insert:
public int postCMark(CMark cMark) {
CMark cm = null;
int status = 0;
try {
status = cMarkingRepository.insertCMark(cMark.getCFk(), cMark.getSCon());
} catch ( Exception e) {
e.printStackTrace();
}
return status;
}
My expectation is that the conversion takes place from the insertCMark() call? I am not sure. In any event, the converter is never called. I would be grateful for any ideas. Thanks!

Answer 1

You're not inserting the whole Entity. So I guess from Spring perspective you just give normal String parameters and Spring probably doesn't know the parameter should somehow be converted.
Despite that shouldn't you even get a compile error because you try to call insertCMark(String, String) as insertCMark(String, List<String>)?
Right now I would say that there is no need for some fancy Spring magic.
You can just tweak the getSCon() method to return a String and convert it in there. Or when you need it for something else to create a second method getSConString():
public String getSCon() {
return this.sCon != null ? String.join(SPLIT_CHAR, this.sCon) : "";
}
Another way is to use your current Converter by hand when calling insertCMark:
public int postCMark(CMark cMark) {
CMark cm = null;
int status = 0;
AttributeConverter<List<String>, String> converter = new StringListConverterCommaDelim();
String sCon = converter.convertToDatabaseColumn(cMark.getSCon());
try {
status = cMarkingRepository.insertCMark(cMark.getCFk(), sCon);
} catch ( Exception e) {
e.printStackTrace();
}
return status;
}