I'm getting data from an external source with no ids and then I store it in my DB. I'm using Spring with JPA (Hibernate). The ids are autogenerated on the first commit.
The changes in the external data is to be updated every night.
The first commit is trivial. I just create new entities for each new data object and save.
But further on I need to track the changes and just update the existing DB entities that have changed (and add and remove).
It doesn't matter which existing entity is to be updated.
How would I need to approach this using Javers? Is there an example?
Currently I'm thinking about something like:
Get existing entities from the DB.
Create new entities from the external data.
?
The new entities have no id. I would like to use Javers get the diff without needing any id. Diff the collections only based on the values.
Following a sample entity. None of the values apart the id is unique. Only the comparison of all other values can be used to check the identity to an existing entity.
#Entity
#Data
public class TiwHier {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#NotNull
private Long id;
#NotBlank
private String prodId;
private String pnGuid;
private String parentPnGuid;
private String typ;
private String name;
private String text;
private String klasse;
}
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 have a model class that I store in Redis and I use Jpa Repository with Spring java. Normally(not with redis) jpa repository is saving the new data or updates(conditionally) if the given model is already exist in Db. Here, I want to add new item to redis but if it is not already exists on db otherwise update it just like usual Jpa implementation.
Here is my model:
#Getter
#Setter
#RedisHash("MyRecord")
public class MyRecordRedisModel {
private String id;
#Id
#Indexed
private String recordName;
private Date startDate;
private Date endDate;
}
And my repository class is just a normal spring jpa repo as follows:
#Repository
public interface IFRecordRedisRepository extends JpaRepository<IFRecordRedisModel, String> {
Page<IFRecordRedisModel> findAll(Pageable pageable);
}
Unique key must be the name (I totally do not care about uniquiness of the id). Thus, if the name is already exist in Db than do not add it again. I marked it as Indexed but still it is adding same data (with same recordName).
How can I make it unique?
This would require an additional query, but I think this solution would work for you. You can use query by Example to check if there exists a record with that name, and save conditionally, or do something else if it already exists.
IFRecordRedisModel exampleRecord = new IFRecordRedisModel();
exampleRecord.setRecordName(inputRecord.getRecordName());
if (!repository.exists(Example.of(exampleModel)))
repository.save(inputRecord);
else ..... // do something else
Say I have the following Collections
public #Data class Customer {
#Id
private String id;
private String firstName;
private String lastName;
#DBRef
private List<Address> addressList= new ArrayList<Address>();
}
and
public #Data class Address {
#Id
private String id;
private String address;
private String type;
private String customerID;
}
And each Customer has multiple addresses, and I have implemented MongoRepository. Saving customer for the First time is working pretty well customerRepo.save(customerObject) and before calling the save I am persisting multiple Address Objects and then setting those to the addressList.
Next time when I am updating the same document and want to add a New set of Address to the existing list it is overwriting the whole addressList array. So basically what I have to do now to set new address like thisexistingCustomerObject.getAddressList().addAll(my new List of address) if there are thousand(or more than thousand) of elements or I am slicing the addressList array the following procedure won't be a good idea. My question is what is the best way to achieve this scenario? say if I don't want to use MongoTemplate. Is it possible Just using the MongoRepository
I don't think you can do it in that way. Previously i had the same situation, and I tried the following
1.org.springframework.core.convert.converter.Converter even I have managed to manipulate the DBObject but functions like $push or $set(wrapping them under key) does not work over there.
2.AbstractMongoEventListener by overriding onBeforeSave but Object manipulation was not taking place during save.
However you can try altering the mentioned
you can try override MongoRepository save method, It would better if someone point to the right direction.
Otherwise for my scenario I had to create Custom repository(To update and delete document) which is working parallel with MongoRepository (for Insert and retrieve data/document), but I believe thats an ugly workaround. There has to be a cleaner way to do it.
Here is a part of Files.java
#Entity(name="files")
public class Files {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String title;
#ElementCollection
private List<String> filenames= new ArrayList<String>();
//<< getter and setter >>
}
it is correctly created the table 'Files' and 'Files_filenames' on mySql
and I can put data there on Controller with it
Files files = new Files();
files.setTitle(ufile.getTitle());
files.setFilenames(Arrays.asList(ufile.getFilename().split(",")));
so far, everything looks ok
However, when I try to get the data from the database, the filename always returns something like 'persistentbag' not ArrayList.
I would like to know how to get ArrayList from the database
I'm using Spring data JPA using Hibernate as a Jpa vendor.
Thanks in advance
PersistentBag is a List (i.e., it implements List), therefore you can use it as a regular List. There is no need to care about actual implementation of that List in this case.
I'm working on a Hibernate/Spring application to manage some movies.
The class movie has a many to many relationship with the class genre.
Both of these classes have generated id's using the GeneratedValue annotation.
The genre is saved through the movie object by using #Cascade(CascadeType.SAVE_UPDATE)
I have placed a unique constraint on the genre's type attribute (which is it's name; "Fantasy" for example).
What I would like to do now is have Hibernate check if there is already a genre with type "Fantasy" and if there is, use that genre's id instead of trying to insert a new record.
(The latter would obviously throw an error)
Finally what I need is something like select-before-update but more like select-before-save.
Is there such a function in Hibernate?
Some code:
Movie class
#Entity
public class Movie {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
private String name;
#Lob
private String description;
#Temporal(TemporalType.TIME)
private Date releaseDate;
#ManyToMany
#Cascade(CascadeType.SAVE_UPDATE)
private Set<Genre> genres = new HashSet<Genre>();
.... //other methods
Genre class
#Entity
public class Genre {
#Column(unique=true)
private String type;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private int id
....//other methods
You may be over-thinking this. Any select-before-update/select-before-save option is going to result in 2 DB round trips, the first for the select, and the second for the insert if necessary.
If you know you won't have a lot of genres from the outset, you do have a couple of options for doing this in 1 RT most of the time:
The Hibernate second-level cache can hold many if not all of your Genres, resulting in a simple hashtable lookup (assuming a single node) when you check for existence.
You can assume all of your genres are already existing, use session.load(), and handle the new insert as a result of the row not found exception that gets thrown when you reference a genre that doesn't already exist.
Realistically, though, unless you're talking about a LOT of transactions, a simple pre-query before save/update is not going to kill your performance.
I haven't heard of such a function in Hibernate select-before-update/select-before-save
In situations like these you should treat Hibernate as if it was JDBC.
First if you want to know if you even have such a Genre you should query for it.
if you do. then the SAVE_UPDATE will not create a new one when you add it to a movie.
if you don't, Hibernate will create a new Genre row in the database and add the connection to the many_to_many table for you.