I have an object that I want to save to both mysql and mongodb
object class is like:
Order:
public long id;
public String brokerID;//UUID
public String userID;//UUID
public String orderID;//UUID
public double price;
public long volume;
the long id field is for mysql to auto_increment and return to me as an OUT parameter,
when I am trying to save two different order objects to mongodb with Spring data, it gives me DuplicateKeyException as it assumes id is my key, and since it's not initialized, both objects have id = 0.
mongoOperation.insert(new Order(UUID.randomUUID().toString(), UUID.randomUUID().toString(), UUID.randomUUID().toString(), 500d, 500l));
mongoOperation.insert(new Order(UUID.randomUUID().toString(), UUID.randomUUID().toString(), UUID.randomUUID().toString(), 500d, 500l));
How am I able to save it to mongodb, rename id to something else?
OK, change the id to some other name like mysqlId resolves this issue
Related
We have model class saved in Redis as mentioned below:-
#Data
#NoArgsConstructor
#AllArgsConstructor
#RedisHash("book")
public class Book implements Serializable {
private static final long serialVersionUID = 2208852329346517265L;
#Id
private Integer bookID;
#Indexed
private String title;
#Indexed
private String authors;
private String averageRating;
private String isbn;
private String languageCode;
private String ratingsCount;
private BigDecimal price;
}
We have title and authors as our indexed property.
Now we wanted to search all the records from Redis by passing title and a list of authors using the spring crud repository as mentioned below.
public interface BookSpringRepository extends CrudRepository<Book, String> {
List<Book> findAllByTitleAndAuthors(String title, List<String> authors);
}
Service layer:-
#Override
public Optional<List<Book>> searchBooksByTitleAndAuthorNames(String title, List<String>
autherNames) {
return Optional.ofNullable(bookSpringRepository.findAllByTitleAndAuthors(title,
autherNames));
}
Here we are getting below exception
Unable to fetch data from Spring data Redis cache using List of Integer or
String.
Getting error while fetching - "Resolved
[org.springframework.core.convert.ConversionFailedException: Failed to convert from type
[java.lang.String] to type [byte] for value 'Ronak';
nested exception is java.lang.NumberFormatException: For input string: "Ronak"]."
We would not want to convert the list of string/integer to byte as it is a time-consuming process and as we tried took so much amount of time. Also when the results are retrieved we will again have to convert back to normal integer or string values.
The other option is to loop through the list and pass a single value at a time to the Redis crud repository and this time Redis crud repository is happy but that will be a loop call to Redis and network latency.
We cannot add ID attributes on authors' property as these can be duplicate records.
Does the spring crud repository support the LIKE query in search that way we can create a unique id having these authors' names and make put ID annotation on that new derived property to search the records using spring crud repository using LIKE or contains kind of query.
Any suggestions here are highly appreciated!!
Try to add serialization to your redis key and value. This might help :
https://medium.com/#betul5634/redis-serialization-with-spring-redis-data-lettuce-codec-1a1d2bc73d26
I'm using spring data mongo. I have a collection within a document that when I add an item to it I would like to assign a new automatically generated unique identifier to it e.g. (someGeneratedId)
#Document(collection = "questionnaire")
public class Questionnaire {
#Id
private String id;
#Field("answers")
private List<Answer> answers;
}
public class Answer {
private String someGeneratedId;
private String text;
}
I am aware I could use UUID.randomUUID() (wrapped in some kind of service) and set the value, I was just wondering if there was anything out of the box that can handle this? From here #Id seems to be specific to _id field in mongo:
The #Id annotation tells the mapper which property you want to use for
the MongoDB _id property
TIA
No there is no out of the box solution for generating ids for properties on embedded documents.
If you want to keep this away from your business-logic you could implement a BeforeConvertCallback which generates the id's for your embedded objects.
#Component
class BeforeConvertQuestionnaireCallback implements BeforeConvertCallback<Questionnaire> {
#Override
public Questionnaire onBeforeConvert(#NonNull Questionnaire entity, #NonNull String collection) {
for (var answer : entity.getAnswers()) {
if (answer.getId() == null) {
answer.setId(new ObjectId().toString());
}
}
return entity;
}
}
You could also implement this in a more generic manner:
Create a new annotation: #AutogeneratedId.
Then listen to all BeforeConvertCallback's of all entities and iterate through the properties with reflection. Each property annotated with the new annotation gets a unique id if null.
I see in most of the coders save data(using spring data) as:
savedEntity = repo.save(savedEntity);
Long id = savedEntity.getId();
I am confused about why most of them assign back the returned value to the saved Entity while the following code also works exact(I have tested myself):
repo.save(savedEntity);
Long id = savedEntity.getId();
Did I miss some benefit of assigning back?
for example, let the entity be:
#Entity
public class SavedEntity {
#Id
private int id;
private String name;
//getter, setters, all arg-constructor, and no-arg constructor
}
Consider the object of SavedEntity is
SavedEntity entity = new SavedEntity(1,"abcd");
now for your first question,
SavedUser entity1 = repo.save(entity);
Long id = entity1.getId();
this entity1 object is the return object getting from the database, which means the above entity is saved in the database succesfully.
for the Second Question,
repo.save(entity);
Long id = entity.getId();//which you got it from SavedEntity entity = new SavedEntity(1,"abcd");
here the value of id is the integer you mentioned in place of id(the raw value).
Most of the time the id (primary key) is generated automatically while storing the entity to the database using strategies like AUTO, Sequence etc. So as to fetch those id's or autogenerated primary key values we assign back the saved entity.
For example:
#Entity
public class Customer {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String firstName;
private String lastName;
}
In this case you'll not pass the id externally but it will create a value for it automatically while storing the data to DB.
I am using Spring Data's Rest Repositories from spring-boot-starter-data-rest, with Couchbase being used as the underlining DBMS.
My Pojo for the object is setup as so.
#Document
public class Item{
#Id #GeneratedValue(strategy = UNIQUE)
private String id;
#NotNull
private String name;
//other items and getters and setters here
}
And say the Item has an id of "xxx-xxx-xxx-xxx" and name of "testItem".
Problem is, that when I want to access the item, I need to be accessible by /items/testItem, but instead it is accessible by /items/xxx-xxx-xxx-xxx.
How do I get use its name instead of its generated id, to get the data.
I found out the answer to my own question.
I just need to override the config for the EntityLookup.
#Component
public class SpringDataRestCustomization extends RepositoryRestConfigurerAdapter {
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.withEntityLookup().forRepository(UserRepository.class).
withIdMapping(User::getUsername).
withLookup(UserRepository::findByUsername);
}
}
Found the info here, though the method name changed slightly.
https://github.com/spring-projects/spring-data-examples/tree/master/rest/uri-customization
If you want query the item by name and want it perform as querying by id,you should make sure the name is unique too.You cant identify a explicit object by name if all objects have a same name,right?
With jpa you could do it like:
#NotNull
#Column(name="name",nullable=false,unique=true)
private String name;
A single JSON is posting from Postman and having two entity names as employee and employee address. From that JSON, empName should be stored in first entity and empAddress should be stored in second entity.
How to do this in Spring Boot? I tried to write only Entities.
First Entity:
class Employee{
private int emId;
private String empName;
//Getters;
//Setter;
}
Second Entity:
class EmployeeAddress{
private int emId;
private String empAddress;
//Getters;
//Setter;
}
My JSON: the firt value in JSON need to be stored in first entity and second need to be stored in second entity. How to do this in Spring Boot from controller?
{
"empName": "sam",
"empAddress:"chennai"
}
You need a DTO.
Something like this:
class Employee{
private String empName;
private String empAddress;
}
So, you can return this object as a Json