I'm trying to persist a LinkedHashMap in a blob field of my db.
My entity looks as follows
#Entity
public class Event {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private long timestamp;
#Lob
private Map<String, Object> payload;
...
My repository looks as follows
#Repository
public interface EventRepositoryInterface extends CrudRepository<Event, Long> {
}
When trying to store my Event object I get the following error message
java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to java.sql.Blob
Any clues about what's wrong?
BLOB is used for storing binary data, BLOB values are treated as binary strings (byte strings). They have no character set, and sorting and comparison are based on the numeric values of the bytes in column values.
I'll suggest that you use TEXT instead.
And also you must use JPA #EntityListeners or Callbacks Methods #PrePersist: and #PostLoad your code become
#Entity
public class Event {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private long timestamp;
#Column(columnDefinition = "TEXT")
private String payload
#Transient
private Map<String, Object> payloadOb;
#PrePersist
public payloadMapToText(){
this.payload = mapToString(this.payloadOb);
}
#PostLoad
public payloadTextToMap(){
this.payloadOb = stringToMap(this.payload);
}
}
You need to add more annotation to the mapping:
#Lob
#MapKeyColumn(name = "key_column")
#Column(name = "value_column")
#ElementCollection
private Map<String, Object> payload;
This is the needed setup, where the map is defined as Map<Basic, Basic>
Related
What is the standard object design for accepting a POST request from a client, saving the record to the database, and then returning a response back to the client? I'm working with the Spring framework.
Should I be sending back the entity and hiding properties that aren't necessary for the response?
#RestController
public class SomeController {
private final SomeService service;
#PostMapping(value = "/post/new", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<SomeEntity> post(#RequestBody final SomeEntity someEntity) {
SomeEntity savedEntity = service.save(someEntity);
return ResponseEntity.ok(savedEntity);
}
}
#Entity
#Table(name = "posts")
public class SomeEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "title")
private String title;
#Column(name = "body")
#JsonIgnore
private String body;
#JsonIgnore
#Column(name = "deleted_ind")
private boolean deleted;
#JsonIgnore
#Column(name = "author")
private String author;
#Column(name = "created_at")
private LocalDateTime createdAt;
}
or would I accept some sort of POST request object that I convert to an entity, then re-assemble the entity into a response?
#JsonIgnoreProperties(ignoreUnknown = true)
public class SomePostRequestResource {
private String title;
private String body;
private String createdAt;
}
#RequiredArgsConstructor
#RestController
public class SomeController {
private final SomeService service;
private final SomeResourceAssembler resourceAssembler;
#PostMapping(value = "/post/new", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<SomePostRequestResource> post(
#RequestBody final SomePostRequestResource someResource
) {
SomeEntity savedEntity = service.convertToEntityAndSave(someResource);
SomePostRequestResource response = resourceAssembler.toResource(savedEntity);
return ResponseEntity.ok(response);
}
}
But then maybe I only want to send back the createdAt, would I hide the other properties in the SomePostRequestResource, or do I need another object to represent the response, which only has the property I want to send back?
I would also appreciate any book or article suggestions related to desigining objects for use with a RESTful API. I have seen articles concerning how to design and name the endpoints, but not so many concerning how to design the objects on the backend.
I would recommend you create a DTO class for the incoming/outgoing data containing the filed that are set/viewable by the client like:
public class SomeEntityIncomingDto {
private String title;
....
}
public class SomeEntityOutgoingDto {
private Long id;
private String title;
....
}
On the other hand, You won't need to map your persistence entities to DTOs and vice versa manually, you can use a library like ModelMapper or MapStruct that handles the conversion automatically.
I have two entities
#Entity
public class Module {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
private String name;
private String descr;
#OneToMany(cascade = {CascadeType.ALL})
#JoinColumn(name="ID", referencedColumnName="ID")
private List<Permissions> perms;
}
#Entity
public class Permissions {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
private Integer clientId;
private String role;
private Character endorseCreate;
private Character endorseUpdate;
private Character endorseDelete;
private Character endorseView;
I am trying to fetch data by first Module.name and Permissions.clientId and Permissions.role
Something like in sql
select * from Module m, Permissions p where m.id=p.id and p.clientId=1 and p.role='ADMIN'
How can I achieve using JPA, I am using spring data aswell.
Can a method be declared in CRUD Repo provided by spring data?
I think the issue is I am unable to find way to pass values to fetch data.
Any help is greatly appreciated
I use Spring Boot and I'd like to save these objects in redis:
#RedisHash("Myobj")
public class Trace implements Serializable {
#Id
#JsonProperty
private final String id;
#JsonProperty
private final TraceType type;
#JsonProperty
private final String clientId;
#JsonProperty
private final String topicId;
#JsonProperty
private final String url;
#JsonProperty
private final String payload;
#JsonProperty
private final Date date;
How can I store these objects and later get some values using the following query:
get all objects for the particular clientId from date date1 to date2.
I use
#Repository
public interface TraceRepository extends CrudRepository<Trace, String> {
to save data this way:
traceRepository.save(trace);
THANK YOU VERY MUCH IN ADVANCE! It's very important for me. Thank you.
I am using JPA with Hibernate in spring boot.
I have two jpa entities
#Entity
#Table(name="courses_type")
public class CoursesType implements Serializable {
private static final long serialVersionUID = 1L;
#Id
private int id;
#Column(name="course_id")
private int courseId;
#Column(name="level")
private int level;
private int credential;
private String status;
private String type;
#Column(name="updated_by")
private int updatedBy;
#Column(name="updated_on")
private Timestamp updatedOn;
#ManyToOne(fetch=FetchType.LAZY, optional=false)
#JoinColumn(name="credential", referencedColumnName="value_id",insertable=false,updatable=false)
#Where(clause="status='live'")
private BaseAttributeList credentialData;
#ManyToOne(fetch=FetchType.LAZY, optional=false)
#JoinColumn(name="level", referencedColumnName="value_id",insertable=false,updatable=false)
#Where(clause="status='live'")
private BaseAttributeList courseLevelData;
... setters and getters
}
Second Entity
#Entity
#Table(name="attribute_list")
public class AttributeList implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name="value_id")
private int valueId;
private String status;
#Column(name="value_name")
private String valueName;
}
Now I am trying to write a JPQL Query in CourseTypeRepo
#Query("Select sct.courseId, sct.credential, sct.credentialData from CoursesType"
+ " sct where sct.courseId IN(?1) and sct.status = ?2")
List<CoursesType> getDataWithAttributes1(ArrayList<Integer> courseId, String status);
Now when I am iterating the result, I am getting class Cast Exception that
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.domain.CoursesType
Basically what I am trying to fetch the complete data using one jpql query.
How should I fix this?
If don't want to fetch full object but only some its properties you have to provide a projection then use it in your query method, for example:
public interface PartialCoursesType {
Integer getCourseId(),
Integer getCredential(),
BaseAttributeList getCredentialData()
}
#Query("select sct.courseId as courseId, sct.credential as credential, sct.credentialData as credentialData...")
List<PartialCoursesType> getDataWithAttributes1(ArrayList<Integer> courseId, String status);
To make the trick works you have to use aliases in the query...
I have a MySQL database and I want to retrieve some data as json.
And I have an entity Offre wich has #OneToMany relation with the AssociationCandidatOffre entity.
and I have an api which calles this method in my repository :
offreRepository.findAll();
Offre entity :
#Entity
public class Offre implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "CODE_OFFRE")
private Long codeOffre;
private String titre;
#OneToMany(mappedBy = "offre")
private Collection<AssociationCandidatOffre> associationCandidatOffres;
public Collection<AssociationCandidatOffre> getAssociationCandidatOffres() {
return associationCandidatOffres;
}
public void setAssociationCandidatOffres(Collection<AssociationCandidatOffre> associationCandidatOffres) {
this.associationCandidatOffres = associationCandidatOffres;
}
//... getters/setters
}
AssociationCandidatOffre entity :
#Entity
public class AssociationCandidatOffre implements Serializable {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
private Long idAssociation;
private String lettreMotivation;
private String tarifJournalier;
private Date dateDisponibilite;
#ManyToOne
private Candidat candidat;
#ManyToOne
private Offre offre;
#JsonIgnore
#XmlTransient
public Candidat getCandidat() {
return candidat;
}
#JsonSetter
public void setCandidat(Candidat candidat) {
this.candidat = candidat;
}
#JsonIgnore
#XmlTransient
public Offre getOffre() {
return offre;
}
#JsonSetter
public void setOffre(Offre offre) {
this.offre = offre;
}
//... getters/setters
}
the problem is when I call the api /offres to return me a json object I get this error message instead :
Failed to write HTTP message: org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: could not extract ResultSet (through reference chain: java.util.ArrayList[0]->com.***.Rekrute.entities.Offre["associationCandidatOffres"]);
nested exception is com.fasterxml.jackson.databind.JsonMappingException: could not extract ResultSet (through reference chain: java.util.ArrayList[0]->com.***.Rekrute.entities.Offre["associationCandidatOffres"])
when I use #JsonIgnore in the getAssocationCandidatOffres I dont get any errors but I want that association in the json result as well.
Normally, this shouldn't generate any error since I have #JsonIgnore in the other side of the relation which is getOffre().
how can I solve this problem ?
You can't convert a bidirectional relation of an enitity to JSON.
You get an endless loop.
JSON-Parser starts with the entity Offer and reads the associated AssociationCandidatOffre via getAssociationCandidatOffres(). For every AssociationCandidatOffre the JSON-Parser read getOffre() and starts again. The parser don't know when he must end.