I was thinking about how to create a Proposal object like this in JHipster: so a User can create a Proposal and other users can vote for it.
entity Proposal {
proposalText String minlength(2) maxlength(100) required
proposalVotes Integer
}
entity Vote {
numberOfPoints Integer
}
relationship ManyToOne {
Vote{proposal(id) required} to Proposal{vote}
Proposal{user(id) required} to User{proposal}
Vote{user(id) required} to User{vote}
}
In Spring I would create that #Transient proposalVotes Integer and the Controller would go and find all the Votes that a Proposal has and add them together to get to the result to be sent to the frontend. That property would not be stored in the database.
If I use JHipster and I add a proposalVotes property, the result would be saved in the database and could be changed in the dialogs(... and I do not like the result), so my question is:
What is the best practice in JHipster when you need a property that is calculated everytime his object is called?
Think of the number of comments in a Blog with Posts, if it is more familiar.
Where do you calculate the result: I would do it in the ProposalResource, but I’m not sure and I haven’t seen any use case like this in the examples, but it looks like a common case.
Thanks a lot
PD: If there is any example in Github, that could be great!
Actually if you are generating entities using JDL(Jhipster domain language) then you wont get any option to make field Transient as JDL is database design mechanism and Transient fields are not going to be placed in DB.
Solution is that after importing JDL to our app you can add Transient fields in your entity class.
Related
Is there a way to set the initial number of votes (assignedVotesPoints) of my entity (ProposalUser) to let's say 100 when the entity is created using JDL?
entity ProposalUser {
creationDate Instant required,
assignedVotesPoints Long
}
I know I could modify the Spring part to somehting like:
private Long assignedVotesPoints = 100L;
But I would like to do it using JDL.
Thanks to all.
No it's not possible currently, feel free to propose a feature request on github though it might be rejected due to policy 2 https://www.jhipster.tech/policies/#-policies
It would have more chances to be accepted if you propose to contribute code that implements it.
I use jhipster and I would like to modify the User entity and add fields and relationships.
I use jhipster entity user and this command is not good.
How can I do it?
User is not a JHipster entity, the generator does not manage it. You must edit the code manually or add a related entity where you put additional fields, see doc: https://www.jhipster.tech/tips/022_tip_registering_user_with_additional_information.html
If you encounter a problem where you need to alter the User entity, Its recommend not doing that. Modifying this default entity might break your app depending on the nature of the changes.
Instead, there are other available solutions like:
creating an entity composed of the User entity
extending the User entity
Using composition
by using OneToOne relation like this
entity ApplicationUser {
additionalField Integer min(42) max(42)
}
relationship OneToOne {
ApplicationUser{internalUser} to User
}
Or
Using inheritance
This solution does the same thing as the previous one, but isn’t as straightforward as the first one because you need to:
create a new entity by hand,
adapt the code to make it use this new entity,
potentially manage yourself the database migration to persist this new entity (depending on the nature of the changes).
More info: https://www.jhipster.tech/user-entity/
I've just started using Jhipster for a simple project with a very simple datamodel (so far).
I have a question regarding the generated code for the one-to-many relationship:
Is it possible to generate with List instead of a Set, so I can have my child-items ordered?
If no, what is the best solution to solve my problem? I see 2 ways:
Change the generated code manually to use a List and then use liquibase (mvn liquibase:diff) to update my database ?
Have an attribute on the child-item to handle the order ?
What is the best way to handle the "problem" ?
Best regards
Martin Elkkjær
You can use the Spring #OrderBy annotation to sort your sets by the child entity. See http://www.objectdb.com/api/java/jpa/OrderBy
#Entity
public class Person {
...
#OrderBy("zipcode.zip, zipcode.plusFour")
public Set<Address> getResidences() {...};
...
}
I'd also recommend the following blog that explains how Sets/Lists differ for Hibernate and JPA: https://vladmihalcea.com/hibernate-facts-favoring-sets-vs-bags/ (where I found the answer originally)
I need to create my own entities using the JHipster using the command "yo jhipster:entity myEntity" that have many-to-one relationship with the User entity that comes by default in JHipster.
I have tried unsuccessfully to create in the wizard a relationship with the entity "user" and the field "login" but it is not working.
What is the good way to do this with JHipster? Or do I have to create the entity without JHipster tool (but I need the CRUD!).
Thanks,
Yann
Just an update - jhipster 2.5.0 was released a few days ago adding support for this. Created this answer since the formatting in comments make i pretty hard to read.
When creating a relation for your entity simply answer the questions like this
? Do you want to add a relationship to another entity? Yes
? What is the name of the other entity? user
? What is the name of the relationship? owner
? What is the type of the relationship? many-to-one
? When you display this relationship with AngularJS, which field from 'user' do you want to use? login
Possible values on how to display the relation could be: id, login, first_name, last_name, email
See https://jhipster.github.io/2015/03/01/jhipster-release-2.5.0.html for moreinformation
Just to add to the correct answer by #stoffer, if you're using the jdl it will look like:
relationship ManyToOne {
Owner{user(email)} to User{owner(name)}
}
at a good sample in an official document is say :
entity Blog {
name String required minlength(3),
handle String required minlength(2)
}
relationship ManyToOne {
Blog{user(login)} to User
}
jdl-samples/blog.jh
If you are using the 1.x version, this wasn't made to work, so basically you should do it by hand, without the generator (but it is definitely doable).
For the 2.x version, we have refactored the User object to have an ID field -> this should make this a lot easier, but as this is not released yet, we don't have a feedback at the moment.
I have come into this issue and solved it by using a simple one-to-one relationship first that will extend the user entity, because it is simple and manageable easily and can make the extended entity be the owner of the relationship, then you can create the many-to-one relationship with your entity, like this example:
entity MyEntity {
MyField Type
...
}
entity ApplicationUser {
additionalField Type
...
}
relationship OneToOne {
ApplicationUser{internalUser} to User
}
relationship ManyToOne {
MyEntity{appUser} to ApplicationUser{myEntities}
}
For more details and approach refer to this jHipster page.
I'm developing an application with Domain Drive Design approach. in a special case I have to retrieve the list of value objects of an aggregate and present them. to do that I've created a read only repository like this:
public interface IBlogTagReadOnlyRepository : IReadOnlyRepository<BlogTag, string>
{
IEnumerable<BlogTag> GetAllBlogTagsQuery(string tagName);
}
BlogTag is a value object in Blog aggregate, now it works fine but when I think about this way of handling and the future of the project, my concerns grow! it's not a good idea to create a separate read only repository for every value object included in those cases, is it?
anybody knows a better solution?
You should not keep value objects in their own repository since only aggregate roots belong there. Instead you should review your domain model carefully.
If you need to keep track of value objects spanning multiple aggregates, then maybe they belong to another aggregate (e.g. a tag cloud) that could even serve as sort of a factory for the tags.
This doesn't mean you don't need a BlogTag value object in your Blog aggregate. A value object in one aggregate could be an entity in another or even an aggregate root by itself.
Maybe you should take a look at this question. It addresses a similar problem.
I think you just need a query service as this method serves the user interface, it's just for presentation (reporting), do something like..
public IEnumerable<BlogTagViewModel> GetDistinctListOfBlogTagsForPublishedPosts()
{
var tags = new List<BlogTagViewModel>();
// Go to database and run query
// transform to collection of BlogTagViewModel
return tags;
}
This code would be at the application layer level not the domain layer.
And notice the language I use in the method name, it makes it a bit more explicit and tells people using the query exactly what the method does (if this is your intent - I am guessing a little, but hopefully you get what I mean).
Cheers
Scott