在具有双向连接的特定实体上运行findById（Long id）Jpa方法时，具有`java.lang.StackOverflowError：null`

Question

I am having a problem with a findById Jpa method for a specific Entity ( CtThhlastikaPressThreats ).
To clarify more about the project it uses Spring Boot, Jpa and MySQL.
There are Entities with bidirectional connections @OneToMany and @ManyToOne while also there is a mappedBy between them and a JoinColumn .

The specific Entity for which I am encountering the problem has a similar bidirectional connection as the DeigmaThhlastikwn Entity ( which has no problem, I once encountered a StackOverflow Exception but it was solved with an annotation of @JsonIgnore . I tried it on this one as well as you can see on the @ManyToOne side DeigmaThhlastikwnXPressThreats Entity but it didn't work )

CtThhlastikaPressThreatsController Rest Controller :

@RestController
@RequestMapping(CtThhlastikaPressThreatsController.BASE_URL)
public class CtThhlastikaPressThreatsController {

public static final String BASE_URL = "/v1/ctThhlastikaPressThreats";

private CtThhlastikaPressThreatsService ctThhlastikaPressThreatsService;

@Autowired
private CtThhlastikaPressThreatsRepositoryImpl ctThhlastikaPressThreatsRepository;

public CtThhlastikaPressThreatsController(CtThhlastikaPressThreatsService ctThhlastikaPressThreatsService) {
    this.ctThhlastikaPressThreatsService = ctThhlastikaPressThreatsService;
}

@CrossOrigin
@GetMapping({"/{id}"})
public CtThhlastikaPressThreats findById(@PathVariable Long id){
    return ctThhlastikaPressThreatsRepository.findCtThhlastikaPressThreatsById(id);
}

@CrossOrigin
@PostMapping()
public CtThhlastikaPressThreats addPressThreat(@RequestBody CtThhlastikaPressThreatDTO ctThhlastikaPressThreatDTO){
    try {
        return ctThhlastikaPressThreatsService.addPressThreat(ctThhlastikaPressThreatDTO);
    }catch (Exception e){
        throw e;
    }
}

@CrossOrigin
@GetMapping({"/getAllActCodes"})
public ArrayList<String> getAllActCodes(){
    try {
        return ctThhlastikaPressThreatsService.getAllActCodes();
    }catch (Exception e){
        throw e;
    }
}
}

CtThhlastikaPressThreats Entity :

package com.teicm.kerkinibackend.domain;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
public class CtThhlastikaPressThreats {

@Id
@Column(name = "id", nullable = false)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@OneToMany(cascade = CascadeType.ALL, mappedBy = "ctThhlastikaPressThreats")
private Set<DeigmaThhlastikwnXPressThreats> deigmaThhlastikwnXPressThreatsSet = new HashSet<>();

@Column(name = "act_code", unique = true, length = 50)
private String actCode;

@Column(name = "description_en")
private String descriptionEn;

@Column(name = "remarks")
private String remarks;

public CtThhlastikaPressThreats addPressThreat(DeigmaThhlastikwnXPressThreats deigmaThhlastikwnXPressThreats){
    deigmaThhlastikwnXPressThreats.setCtThhlastikaPressThreats(this);
    this.deigmaThhlastikwnXPressThreatsSet.add(deigmaThhlastikwnXPressThreats);
    return this;
}

public CtThhlastikaPressThreats() {
}

public CtThhlastikaPressThreats(String actCode, Set<DeigmaThhlastikwnXPressThreats> deigmaThhlastikwnXPressThreatsSet, String descriptionEn, String remarks) {
    this.actCode = actCode;
    this.deigmaThhlastikwnXPressThreatsSet = deigmaThhlastikwnXPressThreatsSet;
    this.descriptionEn = descriptionEn;
    this.remarks = remarks;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public String getActCode() {
    return actCode;
}

public void setActCode(String actCode) {
    this.actCode = actCode;
}

public Set<DeigmaThhlastikwnXPressThreats> getDeigmaThhlastikwnXPressThreatsSet() {
    return deigmaThhlastikwnXPressThreatsSet;
}

public void setDeigmaThhlastikwnXPressThreatsSet(Set<DeigmaThhlastikwnXPressThreats> deigmaThhlastikwnXPressThreatsSet) {
    this.deigmaThhlastikwnXPressThreatsSet = deigmaThhlastikwnXPressThreatsSet;
}

public String getDescriptionEn() {
    return descriptionEn;
}

public void setDescriptionEn(String descriptionEn) {
    this.descriptionEn = descriptionEn;
}

public String getRemarks() {
    return remarks;
}

public void setRemarks(String remarks) {
    this.remarks = remarks;
}
}

DeigmaThhlastikwnXPressThreats Entity :

package com.teicm.kerkinibackend.domain;

import com.fasterxml.jackson.annotation.JsonIgnore;

import javax.persistence.*;

@Entity
public class DeigmaThhlastikwnXPressThreats {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "deigma_thhlastikwn_id")
@JsonIgnore
private DeigmaThhlastikwn deigmaThhlastikwn;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "ct_thhlastika_press_threats_id")
@JsonIgnore
private CtThhlastikaPressThreats ctThhlastikaPressThreats;

@Column(name = "kwdikos_eidous", length = 50)
private String kwdikosEidous;

@Column(name = "press_threat", length = 50)
private String pressThreat;

@Column(name = "importance", length = 50)
private String importance;

public DeigmaThhlastikwnXPressThreats() {
}

public DeigmaThhlastikwnXPressThreats(DeigmaThhlastikwn deigmaThhlastikwn, CtThhlastikaPressThreats ctThhlastikaPressThreats, String kwdikosEidous, String pressThreat, String importance) {
    this.deigmaThhlastikwn = deigmaThhlastikwn;
    this.ctThhlastikaPressThreats = ctThhlastikaPressThreats;
    this.kwdikosEidous = kwdikosEidous;
    this.pressThreat = pressThreat;
    this.importance = importance;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public DeigmaThhlastikwn getDeigmaThhlastikwn() {
    return deigmaThhlastikwn;
}

public void setDeigmaThhlastikwn(DeigmaThhlastikwn deigmaThhlastikwn) {
    this.deigmaThhlastikwn = deigmaThhlastikwn;
}

public CtThhlastikaPressThreats getCtThhlastikaPressThreats() {
    return ctThhlastikaPressThreats;
}

public void setCtThhlastikaPressThreats(CtThhlastikaPressThreats ctThhlastikaPressThreats) {
    this.ctThhlastikaPressThreats = ctThhlastikaPressThreats;
}

public String getKwdikosEidous() {
    return kwdikosEidous;
}

public void setKwdikosEidous(String kwdikosEidous) {
    this.kwdikosEidous = kwdikosEidous;
}

public String getPressThreat() {
    return pressThreat;
}

public void setPressThreat(String pressThreat) {
    this.pressThreat = pressThreat;
}

public String getImportance() {
    return importance;
}

public void setImportance(String importance) {
    this.importance = importance;
}
}

DeigmaThhlastikwn Entity :

package com.teicm.kerkinibackend.domain;

import javax.persistence.*;
import java.sql.Date;
import java.sql.Time;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "deigma_thhlastikwn")
public class DeigmaThhlastikwn {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", nullable = false)
private Long id;

@OneToMany(cascade = CascadeType.ALL, mappedBy = "deigmaThhlastikwn", fetch = FetchType.EAGER)
private Set<DeigmaThhlastikwnXEidh> deigmaThhlastikwnXEidhSet = new HashSet<>();

@OneToMany(cascade = CascadeType.ALL, mappedBy = "deigmaThhlastikwn", fetch = FetchType.EAGER)
private Set<DeigmaThhlastikwnXPressThreats> deigmaThhlastikwnXPressThreatsSet = new HashSet<>();

@Column(name = "kwdikos_deigmatos", nullable = false)
private String kwdikosDeigmatolhpsias;

@Column(name = "xrhmatodothsh")
private String xrhmatodothsh;

@Column(name = "ereunhths")
private String ereunhths;

@Column(name = "topothesia")
private String topothesia;

@Column(name = "date")
private Date date;

@Column(name = "time")
private Time time;

@Column(name = "diarkeia", length = 40)
private String diarkeia;

@Column(name = "tupos_vlasthshs")
private String tuposVlasthshs;

@Column(name = "tupos_oikotopou")
private String tupos_Oikotopou;

@Column(name = "epifaneia_deigmatolhpsias")
private Integer epifaneiaDeigmatolhpsias;

@Column(name = "latitude_egsa")
private Double latitudeEGSA;

@Column(name = "longitude_egsa")
private Double longitudeEGSA;

//    Preferred for Google Maps Markers
@Column(name = "latitude_wgs84")
private Double latitudeWGS84;

//    Preferred for Google Maps Markers
@Column(name = "longitude_wgs84")
private Double longitudeWGS84;

@Column(name = "grid_cell", length = 30)
private String gridCell;

@Column(name = "kwdikos_natura", length = 20)
private String kwdikosNatura;

@Column(name = "methodos_deigmatolhpsias")
private String methodosDeigmatolhpsias;

@Column(name = "parathrhseis")
private String parathrhseis;

@Column(name = "nomos")
private String nomos;

@Column(name = "picture")
@Lob
private Byte picture;

@Column(name = "file")
@Lob
private Byte file;

public DeigmaThhlastikwn() {
}

public DeigmaThhlastikwn(Set<DeigmaThhlastikwnXEidh> deigmaThhlastikwnXEidhSet, Set<DeigmaThhlastikwnXPressThreats> deigmaThhlastikwnXPressThreatsSet, String kwdikosDeigmatolhpsias, String xrhmatodothsh, String ereunhths, String topothesia, Date date, Time time, String diarkeia, String tuposVlasthshs, String tupos_Oikotopou, Integer epifaneiaDeigmatolhpsias, Double latitudeEGSA, Double longitudeEGSA, Double latitudeWGS84, Double longitudeWGS84, String gridCell, String kwdikosNatura, String methodosDeigmatolhpsias, String parathrhseis, String nomos, Byte picture, Byte file) {
    this.deigmaThhlastikwnXEidhSet = deigmaThhlastikwnXEidhSet;
    this.deigmaThhlastikwnXPressThreatsSet = deigmaThhlastikwnXPressThreatsSet;
    this.kwdikosDeigmatolhpsias = kwdikosDeigmatolhpsias;
    this.xrhmatodothsh = xrhmatodothsh;
    this.ereunhths = ereunhths;
    this.topothesia = topothesia;
    this.date = date;
    this.time = time;
    this.diarkeia = diarkeia;
    this.tuposVlasthshs = tuposVlasthshs;
    this.tupos_Oikotopou = tupos_Oikotopou;
    this.epifaneiaDeigmatolhpsias = epifaneiaDeigmatolhpsias;
    this.latitudeEGSA = latitudeEGSA;
    this.longitudeEGSA = longitudeEGSA;
    this.latitudeWGS84 = latitudeWGS84;
    this.longitudeWGS84 = longitudeWGS84;
    this.gridCell = gridCell;
    this.kwdikosNatura = kwdikosNatura;
    this.methodosDeigmatolhpsias = methodosDeigmatolhpsias;
    this.parathrhseis = parathrhseis;
    this.nomos = nomos;
    this.picture = picture;
    this.file = file;
}

// Custom method for adding a new PressThreat for a specific DeigmaThhlastikwn allong with specifying the parent's id in the child object.
public DeigmaThhlastikwn addPressThreat(DeigmaThhlastikwnXPressThreats deigmaThhlastikwnXPressThreats){
    deigmaThhlastikwnXPressThreats.setDeigmaThhlastikwn(this);
    this.deigmaThhlastikwnXPressThreatsSet.add(deigmaThhlastikwnXPressThreats);
    return this;
}

public DeigmaThhlastikwn addXEidh(DeigmaThhlastikwnXEidh deigmaThhlastikwnXEidh){
    deigmaThhlastikwnXEidh.setDeigmaThhlastikwn(this);
    this.deigmaThhlastikwnXEidhSet.add(deigmaThhlastikwnXEidh);
    return this;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public Set<DeigmaThhlastikwnXEidh> getDeigmaThhlastikwnXEidhSet() {
    return deigmaThhlastikwnXEidhSet;
}

public void setDeigmaThhlastikwnXEidhSet(Set<DeigmaThhlastikwnXEidh> deigmaThhlastikwnXEidhSet) {
    this.deigmaThhlastikwnXEidhSet = deigmaThhlastikwnXEidhSet;
}

public Set<DeigmaThhlastikwnXPressThreats> getDeigmaThhlastikwnXPressThreatsSet() {
    return deigmaThhlastikwnXPressThreatsSet;
}

public void setDeigmaThhlastikwnXPressThreatsSet(Set<DeigmaThhlastikwnXPressThreats> deigmaThhlastikwnXPressThreatsSet) {
    this.deigmaThhlastikwnXPressThreatsSet = deigmaThhlastikwnXPressThreatsSet;
}

public String getKwdikosDeigmatolhpsias() {
    return kwdikosDeigmatolhpsias;
}

public void setKwdikosDeigmatolhpsias(String kwdikosDeigmatolhpsias) {
    this.kwdikosDeigmatolhpsias = kwdikosDeigmatolhpsias;
}

public String getXrhmatodothsh() {
    return xrhmatodothsh;
}

public void setXrhmatodothsh(String xrhmatodothsh) {
    this.xrhmatodothsh = xrhmatodothsh;
}

public String getEreunhths() {
    return ereunhths;
}

public void setEreunhths(String ereunhths) {
    this.ereunhths = ereunhths;
}

public String getTopothesia() {
    return topothesia;
}

public void setTopothesia(String topothesia) {
    this.topothesia = topothesia;
}

public Date getDate() {
    return date;
}

public void setDate(Date date) {
    this.date = date;
}

public Time getTime() {
    return time;
}

public void setTime(Time time) {
    this.time = time;
}

public String getDiarkeia() {
    return diarkeia;
}

public void setDiarkeia(String diarkeia) {
    this.diarkeia = diarkeia;
}

public String getTuposVlasthshs() {
    return tuposVlasthshs;
}

public void setTuposVlasthshs(String tuposVlasthshs) {
    this.tuposVlasthshs = tuposVlasthshs;
}

public String getTupos_Oikotopou() {
    return tupos_Oikotopou;
}

public void setTupos_Oikotopou(String tupos_Oikotopou) {
    this.tupos_Oikotopou = tupos_Oikotopou;
}

public Integer getEpifaneiaDeigmatolhpsias() {
    return epifaneiaDeigmatolhpsias;
}

public void setEpifaneiaDeigmatolhpsias(Integer epifaneiaDeigmatolhpsias) {
    this.epifaneiaDeigmatolhpsias = epifaneiaDeigmatolhpsias;
}

public Double getLatitudeEGSA() {
    return latitudeEGSA;
}

public void setLatitudeEGSA(Double latitudeEGSA) {
    this.latitudeEGSA = latitudeEGSA;
}

public Double getLongitudeEGSA() {
    return longitudeEGSA;
}

public void setLongitudeEGSA(Double longitudeEGSA) {
    this.longitudeEGSA = longitudeEGSA;
}

public Double getLatitudeWGS84() {
    return latitudeWGS84;
}

public void setLatitudeWGS84(Double latitudeWGS84) {
    this.latitudeWGS84 = latitudeWGS84;
}

public Double getLongitudeWGS84() {
    return longitudeWGS84;
}

public void setLongitudeWGS84(Double longitudeWGS84) {
    this.longitudeWGS84 = longitudeWGS84;
}

public String getGridCell() {
    return gridCell;
}

public void setGridCell(String gridCell) {
    this.gridCell = gridCell;
}

public String getKwdikosNatura() {
    return kwdikosNatura;
}

public void setKwdikosNatura(String kwdikosNatura) {
    this.kwdikosNatura = kwdikosNatura;
}

public String getMethodosDeigmatolhpsias() {
    return methodosDeigmatolhpsias;
}

public void setMethodosDeigmatolhpsias(String methodosDeigmatolhpsias) {
    this.methodosDeigmatolhpsias = methodosDeigmatolhpsias;
}

public String getParathrhseis() {
    return parathrhseis;
}

public void setParathrhseis(String parathrhseis) {
    this.parathrhseis = parathrhseis;
}

public String getNomos() {
    return nomos;
}

public void setNomos(String nomos) {
    this.nomos = nomos;
}

public Byte getPicture() {
    return picture;
}

public void setPicture(Byte picture) {
    this.picture = picture;
}

public Byte getFile() {
    return file;
}

public void setFile(Byte file) {
    this.file = file;
}
}

Just to inform, adding a new CtThhlastikaPressThreats is done successfully. Also the MySQL schema is created automatically on Run .

The project's github page is on https://github.com/alexgil1994/kerkinibackend

The Stack trace of the Error is ( and it keeps the same way recurcivelly, i didn't insert the whole stack because you can see already it repeats itself ) :

2018-11-19 21:59:48.808 ERROR 1372 --- [nio-8080-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Handler dispatch failed; nested exception is java.lang.StackOverflowError] with root cause

java.lang.StackOverflowError: null
at org.springframework.data.repository.util.ClassUtils.unwrapReflectionException(ClassUtils.java:154) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:646) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:117) ~[spring-data-jpa-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at com.sun.proxy.$Proxy112.findCtThhlastikaPressThreatsById(Unknown Source) ~[na:na]
at sun.reflect.GeneratedMethodAccessor63.invoke(Unknown Source) ~[na:na]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:206) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at com.sun.proxy.$Proxy94.findCtThhlastikaPressThreatsById(Unknown Source) ~[na:na]
at com.teicm.kerkinibackend.repositories.CtThhlastikaPressThreatsRepositoryImpl.findCtThhlastikaPressThreatsById(CtThhlastikaPressThreatsRepositoryImpl.java:37) ~[classes/:na]
at com.teicm.kerkinibackend.repositories.CtThhlastikaPressThreatsRepositoryImpl$$FastClassBySpringCGLIB$$f23e415a.invoke(<generated>) ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at com.teicm.kerkinibackend.repositories.CtThhlastikaPressThreatsRepositoryImpl$$EnhancerBySpringCGLIB$$b6491b5e.findCtThhlastikaPressThreatsById(<generated>) ~[classes/:na]
at sun.reflect.GeneratedMethodAccessor64.invoke(Unknown Source) ~[na:na]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:359) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:644) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:117) ~[spring-data-jpa-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.1.RELEASE.jar:2.1.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at com.sun.proxy.$Proxy112.findCtThhlastikaPressThreatsById(Unknown Source) ~[na:na]
at sun.reflect.GeneratedMethodAccessor63.invoke(Unknown Source) ~[na:na]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:206) ~[spring-aop-5.1.1.RELEASE.jar:5.1.1.RELEASE]
at com.sun.proxy.$Proxy94.findCtThhlastikaPressThreatsById(Unknown Source) ~[na:na]
at com.teicm.kerkinibackend.repositories.CtThhlastikaPressThreatsRepositoryImpl.findCtThhlastikaPressThreatsById(CtThhlastikaPressThreatsRepositoryImpl.java:37) ~[classes/:na]

I apologize for any wrong-doings, the project is at the early stages of my Thesis.

Any help is really appreciated.

Update - Solved:

After following the suggestions in the answers the problem was solved. There is farther explanation under the Correct Answer at one of my comments.
Also if anyone is interested to see all the changes with details you can have a look at the commit that solved the problem at :
https://github.com/alexgil1994/kerkinibackend/commit/230c1df96623363c61317216913b310c1c7ec231

Answer 1

I'd start by adding the following to you application.properties file so you can see exactly what sql statements are called.

# Log sql statements and their parameters
logging.level.org.hibernate.SQL=debug
logging.level.org.hibernate.type.descriptor.sql=trace

@JsonIgnore won't help with reading the data. That only comes into when you're using Jackson to convert the objects to Json. ie when you return data from the RestController.

I just had a look at the ctThhlastikaPressThreatsRepository.findCtThhlastikaPressThreatsById method in the repo on github. It appears to be calling itself, that'll cause the stack overflow.

public CtThhlastikaPressThreats findCtThhlastikaPressThreatsById(Long id){
    try {
        // TODO: 11/17/2018 !!! -- Try as an Optional findById(id) instead!!!
        return ctThhlastikaPressThreatsRepository.findCtThhlastikaPressThreatsById(id);
    }catch (Exception e){
        throw  e;
    }
}

It's very confusing how you are using spring and jpa. I would either use your own @Repository (the Impl version you have) or stick with the extending the CrudRepository. Don't try and do both.

If you want to use the CrudRepository, all you need is to have something like you already have.

public interface CtThhlastikaPressThreatsRepository extends CrudRepository<CtThhlastikaPressThreats, Long>, org.springframework.data.repository.Repository<CtThhlastikaPressThreats, Long> {

    Optional<CtThhlastikaPressThreats> findById(Long id);

    CtThhlastikaPressThreats findCtThhlastikaPressThreatsById(Long id);

    @Query(nativeQuery = true, value = "SELECT DISTINCT ct.act_code FROM ct_thhlastika_press_threats ct ORDER BY act_code ASC")
    ArrayList<String> findDistinctByActCodeOrderByActCode();
}

You should be able to remove the Impl version and just use this.

I'd suggest you write some test classes to make debugging easier.

eg

@RunWith(SpringJUnit4ClassRunner.class)
@DataJpaTest
public class CtThhlastikaPressThreatsRepositoryImplTest {

    @Autowired
    private CtThhlastikaPressThreatsRepository ctThhlastikaPressThreatsRepository;

    @Test
    public void findByIdTest() {
        CtThhlastikaPressThreats pressThreats = new CtThhlastikaPressThreats();
        pressThreats.setActCode("actcode");
        pressThreats.setDescriptionEn("description");
        pressThreats.setRemarks("remarks");
        ctThhlastikaPressThreatsRepository.save(pressThreats);

        CtThhlastikaPressThreats found = ctThhlastikaPressThreatsRepository.findById(pressThreats.getId()).orElse(null);
        assertEquals("description", found.getDescriptionEn());

        CtThhlastikaPressThreats found2 = ctThhlastikaPressThreatsRepository.findCtThhlastikaPressThreatsById(pressThreats.getId());
        assertEquals("description", found2.getDescriptionEn());
    }

    @Test
    public void listCodesTest() {
        CtThhlastikaPressThreats pressThreats = new CtThhlastikaPressThreats();
        pressThreats.setActCode("actcode1");
        pressThreats.setDescriptionEn("description1");
        pressThreats.setRemarks("remarks1");
        ctThhlastikaPressThreatsRepository.save(pressThreats);
        pressThreats = new CtThhlastikaPressThreats();
        pressThreats.setActCode("actcode2");
        pressThreats.setDescriptionEn("description2");
        pressThreats.setRemarks("remarks2");
        ctThhlastikaPressThreatsRepository.save(pressThreats);
        List<String> expected = Arrays.asList(new String[] {"actcode1", "actcode2"});

        ArrayList<String> found = ctThhlastikaPressThreatsRepository.findDistinctByActCodeOrderByActCode();
        assertTrue(found.containsAll(expected) && expected.containsAll(found));
    }
}