I got a problem with simple Spring Data issue. Let's assume we got two entities.
public class Request {
// all normal stuff
#ManyToOne
private Document doc;
}
public class Document {
private Long id;
private String name;
}
Simple relation. My question is - is it possible to retrieve Request entities using Spring Data Method-DSL and sorting by Document? So what I want to achieve is to create repository method like:
public List<Request> findAllOrderByDoc()
or similar:
public List<Request> findAllOrderByDocId()
Unfortunately when I try that I am given error message saying that there is no Doc field or it cannot be mapped to long. I assume it is possible to be done using QueryDSL and predicates but I am wondering if this pretty obvious and simple thing can be done by plain Spring Data?
Yes, sure.
you need to provide the direction:
public List<Request> findAllOrderByDocAsc()
public List<Request> findAllOrderByDocDesc()
Related
I have a spring app, that pushes data in an s3 bucket.
public class Ebook implements Serializable {
#Column(name= "cover_path", unique = true, nullable = true)
private String coverPath;
private String coverDownloadUrl;
#Value("${aws.cloudfront.region}")
private String awsCloudFrontDns;
#PostLoad
public void init(){
// I want to access the property here
System.out.println("PostConstruct");
String coverDownloadUrl = "https://"+awsCloudFrontDns+"/"+coverPath;
}
When a data is pushed, let's say my cover here, I get the key 1/test-folder/mycover.jpg which is the important part of the future http URL of the data.
When I read the data from database, I enter inside #PostLoad method and I want construct the complete URL using the cloudfront value. This value changes frequently so we don't want to save hardly in the database.
How could I do to construct my full path just after reading the data in database?
The only way to do this is to use a service that update the data after using repository to read it? For readbyId it can be a good solution, but for reading list or using other jpa methods, this solutions won't work because I have each time to create a dedicated service for the update.
It doesn't look good for Entity to depend on property.
How about EntityListener.
#Component
public class EbookEntityListener {
#Value("${aws.cloudfront.region}")
private String awsCloudFrontDns;
#PostLoad
void postload(Ebook entity) { entity.updateDns(awsCloudFrontDns); }
}
I recommend trying this way :)
Good day fellow hibernators!
I have a question on how the DistinctBy clause works in conjunction with Spring Data's projection
Assume I have 3 classes:
public class Task {
Long id;
#ManyToOne(fetch = LAZY)
#JoinColumn(name = "project_id")
private Project project;
#OneToOne
#JoinColumn(name = "contact_id")
private Contact assigned;
Boolean deleted;
// ...
}
public class Contact {
Long id;
// ...
}
public class Project {
Long id;
#OneToMany(fetch = LAZY, mappedBy = "project")
private Set<Task> tasks;
// ...
}
These would be my domain classes. Notice, Project does have a "One2Many" to Tasks, Contact does not. Now, I have 2 interfaces for my projections and the basic TaskRepo with 2 methods:
public interface JustProject {
Project getProject();
}
public interface JustAssignee {
Contact getContact();
}
public class TaskRepo extends CrudRepository<Task, Long>, JpaSpecificationExecutor<Task> {
List<JustAssignee> findDistinctByDeletedFalse();
List<JustProject> findDistinctByDeletedFalseAndDeletedFalse();
}
The way it works for me right now is that, findDistinctByDeletedFalse returns as many instances as there are distinct contacts for tasks (e.g. if there are 10 tasks but only 3 contacts, the method will return just 3 objects containing all the 3 distinct contacts). Same for findDistinctByDeletedFalseAndDeletedFalse but on project level.
Now I have a few questions here and would love to get some help in understanding how this works exactly.
is the distinct clause applied after the search is done?
my initial assumption was that this behavior would not work as it does now. I assumed that the distinct clause is applied before the result is fetched, meaning that it would be DISTINCT based on the underlying task model, not the returned JustContact or JustProject model.
is there any way I could somehow not abuse the ...AndDeletedFalse redundant appendix? I need both the two methods from the repo but I feel like I had to cheat just to obtain that result...
... am I doing something wrong? I wanted to get "all distinct contacts/projects assigned to all tasks" as elegant of a way as possible. I ended up thinking about this distinctby exactly because I was unsure on how it works and wanted to try mu luck out. I really didn't think it would work this way, but now that it does I would really want to understand why it does!
Many thanks <3
The DISTINCT keyword is applied to the query and therefore it's effect depends on the select list which in turn is controlled by the projection. Therefore if you have only project or only contact in your projection the DISTINCT will get applied to those values only. Note though, that this relies somewhat on the boundaries of the JPA specification and I wouldn't be surprised if you see different behaviour with different implementations. See https://github.com/eclipse-ee4j/jpa-api/issues/189 and https://github.com/eclipse-ee4j/jpa-api/issues/124 for somewhat related issues raised against the specification.
In oder to differentiate methods that otherwise only differ in the return value you might add any additional string between find and By in the method name. For example you might want to rename your methods to findDistinctContactsByDeletedFalse and findDistinctProjectsByDeletedFalse
I guess this is the best that you can get with Spring Data JPA. You might be able to use just a single method by using the dynamic projections approach, but I think this is a perfect use case for Blaze-Persistence Entity Views.
I created the library to allow easy mapping between JPA models and custom interface or abstract class defined models, something like Spring Data Projections on steroids. The idea is that you define your target structure(domain model) the way you like and map attributes(getters) via JPQL expressions to the entity model.
A DTO model for your use case could look like the following with Blaze-Persistence Entity-Views:
#EntityView(Task.class)
public interface TaskAggregateDto {
// A synthetic "id" to get a grouping context on object level
#IdMapping("1")
int getGroupKey();
Set<ProjectDto> getProjects();
Set<ContactDto> getContacts();
#EntityView(Project.class)
interface ProjectDto {
#IdMapping
Long getId();
String getName();
}
#EntityView(Contact.class)
interface ContactDto {
#IdMapping
Long getId();
String getName();
}
}
The Spring Data integration allows you to use it almost like Spring Data Projections: https://persistence.blazebit.com/documentation/entity-view/manual/en_US/index.html#spring-data-features
public interface TaskRepo extends CrudRepository<Task, Long>, JpaSpecificationExecutor<Task> {
TaskAggregateDto findOneByDeletedFalse();
}
I'm just getting started with elasticsearch with spring which is both technologies which are completely new to me. I have uploaded data to an elasticseach index with logstash and I can search it successfully using kebana. However when I try to return from an index to a webpage using spring it only returns empty json-objects, but the right amount of empty objects. Did I upload the data incorrectly or is something wrong with my code? I don't understand why this is happening and would appreciate any help I can get. You can find some code below.
Code for type:
#Document(indexName="usmgbg_index", type="usmgbg_type")
public class Usmgbg {
#Id
private String ID;
private String Source, Name, Profession, Country, FileName, LastModified, OwnerID;
}
Repository:
#Repository
public interface UsmgbgRepository extends ElasticsearchRepository<Usmgbg, String>{}
Controller:
#RestController
public class UsmgbgController {
#Autowired
private UsmgbgRepository repository;
#GetMapping("usmgbg/findall")
public List<Usmgbg> findAllCustomers() {
List<Usmgbg> items = new ArrayList<>();
repository.findAll().forEach(items::add);
return items;
}
}
The output I'm getting from findAllCustomers looks like:
[{},{},{},{},....]
I realize this is an old question but I had the same issue (maybe for a different reason) and I solved it by adding getters and setters in the model.
Iterable is returned from findAll().
If you want to get list you should get content first.
Change
#Repository
public interface UsmgbgRepository extends
ElasticsearchRepository<Usmgbg, String>{
Page<Usmgbg> findAll();
}
And then
repository.findAll().getContent().forEach(items::add);
Or fix your code to iterate over the results.
Another solution is to use search method in ElasticsearchRepository using QueryBuilders API.
Iterable<Usmgbg>=
repository.search(QueryBuilders.matchAllQuery);
Adding my experience
spring-data requires getters to follow the POJO naming, i.e: getSomething()
so it did not work (spring-data did not send any fields to ElasticSearch when saving the #Document, resulting in an empty _source in ES) when having Lombok #Accessors(fluent = true), as it removes the get prefix on getters ...
I recently asked this question : Spring Mongodb - Insert Nested document?
And found out that Spring-Data-MongoDB does not support such behavior - so now I need a working alternative.
Now - to avoid having you look at the code on another page, I am going to paste it here from the other question... Here are my two POJOs :
#Document
public class PersonWrapper {
#Id
private ObjectId _Id;
#DBRef
private Person leader;
#DBRef
List<Person> delegates;
// Getters and setters removed for brevity.
}
public class Person
{
#Id
private ObjectId _Id;
private String name;
// Getters and setters removed for brevity.
}
Now, what I want to be able to do here - is send up a JSON object in my POST request as follows :
{
"personWrapper":
{
"_Id":"<ID HERE (MIGHT WANT SQL TO GENERATE THIS DURING CREATE>",
"leader":{
"_Id":"<ID HERE (MIGHT WANT SQL TO GENERATE THIS DURING CREATE>",
"name":"Leader McLeaderFace"
},
delegates:[{...},{...},{...}]
}
}
At this point - I would like the SQL side of this to create the individual records needed - and then insert the PersonWrapper record, with all of the right foreign keys to the desired records, in the most efficient way possible.
To be honest, if one of you thinks I am wrong about the Spring-Data-MongoDB approach to this, I would still be interested in the answer - because it would save me the hassle of migrating my database setup. So I will still tag the spring-data-mongodb community here, too.
If I understand well you want to cascade the save of your objects ?
ex : you save a PersonWrapper with some Person in the delegates property and spring data will save PersonneWrapper in a collection and save also the list of Person in another Collection.
It is possible to do that with Spring DATA JPA if you annotate your POJO with the JPA annotation #OneToMany and setup cascade property of this annotation. See this post
However the cascade feature is not available for Spring DATA mongoDB. See documentation .First you have to save the list of Person and then you save PersonWrapper.
I'm trying to get the created datetime of the last created item in a mongodb repository.
I could obviously use a findAll(Sort sort) function, and get the first element, but this would not be very practical on a large database.
Mongo queries do not support an "orderBy" query method so this is also not a solution.
The order of creation is in chronological order of "created" so if I can get the last created document in the collection that would be good too.
So my question is:
What is the best way to retrieve the last created document in a mongodb repo using Spring data?
My current code:
#Data
#Document
public class Batch
{
#Id
String id;
LocalDateTime created;
//other stuff
}
public interface BatchRepository extends MongoRepository<Batch,String>
{
//this does not work
//Batch findOneOrderByCreatedDesc();
}
Try the following one, it should work well
public interface BatchRepository extends MongoRepository<Batch,String>
{
Batch findTopByOrderByCreatedDesc();
}
Notice that the method name slightly differs from your variant, this difference is important as spring parses the method name and builds a query based on the result of parsing.