Spring Data JPA - findByAlias vs. findUserByAlias - error with both - spring

Question

I am using spring boot 2 with JPA and Spring Security.
I have a handler method that, depending upon a dropdown, will find all links either similar to a specific title or posted by a specific user. I know my database is set up properly.
I am getting a null pointer exception at this line:
Optional<User> user = userRepository.findUserByAlias("searchTerm");
I have tried changing the method to findByAlias(...) with the same result.
This is the code for my UserRepository:
public interface UserRepository extends JpaRepository<User, Long> {
Optional<User> findByEmail(String email);
Optional<User> findUserByAlias(String alias);
Optional<User> findByAlias(String alias);
}
and this is my handler method wherein the error occurs at this line:
Optional<User> user = userRepository.findUserByAlias("searchTerm");
#GetMapping("/search")
public String showSearchResults(#RequestParam("searchTerm") String searchTerm, #RequestParam("searchBy") String searchBy, Model model) {
System.out.println("INSIDE showSearchResults + searchTerm =" + searchTerm);
List<Link> searchResults;
if(searchBy.equals("user")) {
System.out.println("INSIDE IF EQUALS 'user'");
// get the user by alias
Optional<User> user = userRepository.findUserByAlias("searchTerm");
// if the user is present the find all links by the user id
if (user.isPresent()) {
searchResults = linkRepository.findAllByUser_Id(user.get().getId());
} else {
searchResults = null;
}
}
if(searchBy.equals("title")){
searchResults = linkRepository.findAllByTitleLike("%" + searchTerm + "%");
} else {
searchResults = null;
}
model.addAttribute("searchTerm", new SearchTerm());
model.addAttribute("searchResults", searchResults);
return "search-results";
}
and this is my User class:
#Entity
public class User implements UserDetails {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private Long id;
#Column
private String email;
#Column
private String password;
#Column
private boolean enabled;
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(
name = "users_roles",
joinColumns = #JoinColumn(name = "user_id", referencedColumnName = "id"),
inverseJoinColumns = #JoinColumn(name = "role_id", referencedColumnName = "id")
)
private Set<Role> roles = new HashSet<>();
#Column
private String firstName;
#Column
private String lastName;
#Column
private String fullName;
#Column
private String alias;
#Transient
private String confirmPassword;
public User(){
}
public User(String email, String password, boolean enabled,
String firstName, String lastName,
String fullName, String alias) {
this.email = email;
this.password = password;
this.enabled = enabled;
this.firstName = firstName;
this.lastName = lastName;
this.fullName = fullName;
this.alias = alias;
}
public void addRole(Role role){
roles.add(role);
}
public void addRoles(Set<Role> roles) {
roles.forEach(this::addRole);
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public boolean isEnabled() {
return enabled;
}
public void setEnabled(boolean enabled) {
this.enabled = enabled;
}
public Set<Role> getRoles() {
return roles;
}
public void setRoles(Set<Role> roles) {
this.roles = roles;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getFullName() {
return firstName + " " + lastName;
}
public void setFullName(String fullName) {
this.fullName = fullName;
}
public String getAlias() {
return alias;
}
public void setAlias(String alias) {
this.alias = alias;
}
public String getConfirmPassword() {
return confirmPassword;
}
public void setConfirmPassword(String confirmPassword) {
this.confirmPassword = confirmPassword;
}
#Override
public Collection<? extends GrantedAuthority> getAuthorities() {
List<SimpleGrantedAuthority> authorities = new ArrayList<>();
for(Role role : roles){
authorities.add(new SimpleGrantedAuthority(role.getName()));
}
return authorities;
}
#Override
public String getUsername() {
return null;
}
#Override
public boolean isAccountNonExpired() {
return true;
}
#Override
public boolean isAccountNonLocked() {
return true;
}
#Override
public boolean isCredentialsNonExpired() {
return true;
}
}
So I have two questions:
1.) First and most importantly - why am I getting null pointer exception? I'm at a loss as to how to go about debugging this.
2.) What is the difference between findByAlias and findUserByAlias?
Any advice would be much appreciated.
Thank you for your help,
Marc

Answer 1

How is your userRepository injected into your controller? It seems that is the most likely reason for the null pointer.