I have 2 models, one called Employee and another one User,
Employee has one field pointing to User, one to one relationship.
My problem is that i need one query method to find the Employee that has the user with certain id. I need to find the Employee with certain User id.
I know the default query methods: .findOne, .findAll, but i need to create one, alright? how i can do that? i searched a lot but probably i am missing something. I didn't found how to do a query like that.
Thanks
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I am working on a multi-country application where I have different db schemas for each country. I want to understand how can i call a different query file based on the country a user belongs to.. One way i thought of was maintaining different query files for different countries (IqueryConstantsIndia, IQueryConstntChina etc) and to check the country of the user in the constructor of the repository class and then call the query file based on the same but how do i return a class name is what i am stuck with.. Can anyone help on this or if you think there is a better way of implementing this.
I've been researching this for a while and still couldn't find a satisfactory answer for my problem.
I have an entity on my postgres DB (product) that has a ManyToOne relationship with another entity (Dun).
Each product may have N duns.
On my PUT endpoint, the desired behavior would be:
Every time I update a product, it replaces all the duns with the ones provided on the endpoint.
Is there any way to handle it automatically by Hibernate/JPA?
In order to make it easier to test and explain the issue, I've uploaded a project on Github on the following link https://github.com/brunapereira/jpaexample
If there's no way to handle it automatically by JPA, what's the best way to solve it with code?
Thanks in advance,
First, you need to remove Duns by product id, then get the product by id, add the new duns then save back.
I'm making a system (using Spring + JPA with MySQL) that shows the best applicants for a certain job offer. The company and the applicants have their respective user account, and with that, they can fill in their personal/company information and their job profile/job offer conditions. With that, the system should match the job conditions (like 3+ years of experience in C) with the applicant's job profile.
My problem is that the User Account is created first, and should be independent, but these two different entities (Applicant and Company), with different attributes, are using it. So if I do something like create an applicant and company in the User Account, one of them will be always null.
How can I solve this? I guess the problem would be something like: how to implement a user account that can hold data from different entities that have different attributes (therefore, can't be grouped)? (In fact, I need one more entity, but I tried to simplify it to illustrate the problem more clearly).
I think, you should make marker interface, like public interface UserAccountable or smth. Implement this interface in your Applicant and Company classes. Then you can make a field in UserAccount class, like private UserAccountable someUser; and throught setters and getters you can assign and get this variable to Applicant or Company.
Hope this helps!
I found what I needed here: https://thoughts-on-java.org/complete-guide-inheritance-strategies-jpa-hibernate/
The problem was the mapping, not the class design per se. I could create interfaces and abstract classes to solve it in the Java world, but in the SQL world that's not possible, so the mapping is the key. In this case, I was looking for the Joined table mapping, but I realized I needed it just to not have null fields in my UserAccount, because I don't need a polymorphic query (e.g. give me the names of every 'user type' (Person, Company)), and it would be too costly performance wise to implement it that way, so I'll trade off space for performance, and I'll just reference all three user types in the User Account, leaving two of those three fields null forever.
PS: Single table mapping won't help because I do need to use not null conditions.
I have 2 different JSON Files. One with user details and other with order details. Order details table has a column user_id to match the user ordered for. I have to create a dynamo db table that has the order details nested inside the user details and insert the values from the Json files into this table using a spring-boot app. Can someone help me with this ? Do we have any example code ?
DynamoDB is NOT a relational DB so you can't have relations per se.
However, you have two ways (at least those come to my mind) to achieve what you want.
1) Have two tables: User and Order, the latter with userId field. When you load Order, get your userId and load also a User by the index id.
2) In your User.java you can have field List<Order> orders. Then you need to create Order.java and annotate this class with #DynamoDBDocument. This enables you to have custom objects in your #DynamoDBTable classes. Do not also forget about getters and setters since they are required.
I'm having trouble figuring out a data model for my project. I'm using Parse as the backend.
I intend to have users who are in groups, and the groups have text posts. What should be classes, and what should be rows in those classes.
I'm guessing a good way to do this would be, have a group, user, and post class.
The columns for the group class would be: GroupID, GroupName, postID, UserID
The columns for the user class would be: UserID, GroupsUserBelongsTo, user name, password, email
The columns for the post class would be: UserIDPostBelongsTo, GroupID, TextFile, TimeCreated
Is there anything I'm missing, or I should change.
You're thinking is a very SQL / rows based way and you shouldn't, this isn't SQL, it's objects and relationships.
So, your classes are fine, and the actual data is fine, but where you're using ids you should be using relationships. Post should just have a pointer to user. Perhaps, don't bother with a relationship from user to groups (you can query that using the other relationship), though you can, particularly if you will have lots of users / groups.
You may also want to consider roles to provide security for the groups.