What is the correct way to specify a one-to-many relationship in Spring Web MVC (using Spring Roo)?
Example: A Person has a name and an email. A Team has a name. A Person has a membership in a Team, and a Team has zero or more members. The user would like to a) Set the membership for a person, b) Set the members for a Team.
If the relation is created using a reference field for Person, members are not visible in the view for Team. There's a similar result if the relation is created using a set field for Team (which really is a many-to-many relation anyway).
What am I missing?
What you need here is a bidirectional relationship (which is not created by default).
When you generate your entities, you need to add both the Set association in Team, AND the Person association in Team. It will probably also be a good idea (depending on your naming convention to add the mappedBy attribute in the OneToMany annotation on the generated Team Set. If you want to get this done by Roo, just used --mappedBy on the field set command. The value for this will be the field name of the Team reference in the Person entity.
With both references in place, roo should generate the correct scaffolding.
Related
Let's say I have a Setting entity with some fields like IntValue, dateValue, stringValue and some linked entities, like countries (ManyToMany to entity Country), languages (ManyToMany to Language) etc.
Settings are created by users and assigned to specific objects (not important here, but I wanted to clarify).
Now I suddenly need to have UserDefaultSetting, which will be the same, but with additional user field (ManyToOne to User entity).
I tried to extend existing Setting entity class with one more field added. The problem is, as I looked at the schema update SQL, it created new table for the new entity, but without all the tables needed to ORM connections (mostly ManyToMany). Just one table with "scalar" fields.
So previously I've had setting table with int_value, date_value etc. but also setting_country and setting_language tables, linking ManyToMany relations. After creating child entity, Doctrine created only user_default_setting table with int_value, date_value etc. and additionally user_id column, but I can't see any relation/link tables.
I know I should've been do it with abstract base entity class, but at the time I started, I didn't know that and now part of the project is on production (don't look at me like that, I blame the client) and I don't want to change that "base" class now. Can I inherit everything from non-abstract entity class in a way it will work?
UPDATE: everything explained. See Cerad's comment. Thanks!
I have entities "Article" and "Product". Now I want to add comments to these 2 entities. Should I create 2 different entities "ArticleComment" and "ProductComment" with the same properties, and build a ManyToOne relation to their respective entity, or create a single "Comment" entity and find a way to build a relation to both "Article" and "Product" entities. Considering solution #2, how could I do that ?
Considering solution #2, how could I do that ?
One way would be to use Single Table Inheritance
Single Table Inheritance is an inheritance mapping strategy where all classes of a hierarchy are mapped to a single database table. In order to distinguish which row represents which type in the hierarchy a so-called discriminator column is used.
This means that you can easily create two separate entities ArticleComment and ProductComment both extending Comment. Then you use the advantages DiscriminatorMap column provides.
Your Comment entity could hold a relation called parent for instance that would refer to either your Article or Product entities. By creating new instance of ArticleComment or ProductComment your discriminator map field would be automatically populated depending on which type you're using.
This would also give you advantages with using DQL to query related comments by their type. Example from documentation:
$query = $em->createQuery('SELECT u FROM Doctrine\Tests\Models\Company\CompanyPerson u WHERE u INSTANCE OF Doctrine\Tests\Models\Company\CompanyEmployee');
And more. You can read that chapter here. Of course this is just a sample and you can use completely different approach.
Suppose i have an Bundle to manage anything related to advertisements.
This bundle contains an Entity Advertisement. this has an field for relation purposes: lets say relation field
Suppose i have an Entity Company and an Entity Events in different Bundles
(In companies there are companies stored and in events there are events stored.)
Case:
The entities have a relation to multiple Advertisements.
A single Advertisement has a relation to only one of the entities.
From the perspective advertisement:
I want to be able to select one of the entities (entity.id) to view or update the reference (like dropdown)
From the perspective of an event or a company:
I want to be able to select/add/delete multiple advertisements (like the symfony collection form type)
all this preferred without the use of foreign-keys.
the entities are like "modules" so there can be more than just these entities.
I think you just have to use OneToOne (For Advertisement) and OneToMany (For Company and Events) relations.
It's easy to use, read this doc : http://docs.doctrine-project.org/en/2.0.x/reference/association-mapping.html
im starting to implement some security features in my application. When initially trying to implement some ACL I came acress two questions I could not figure out:
Where to implement the setting of acl
I could do it in the controller action where my entities are created or on the entity itself with lifecyclecallbacks. For example I have a Group Entity which holds some Userentities. It is easier to set the view or edit access on a lifecyclecallback for all group entities. I would prefer to make my controller as slim as possible. Or is this a bad approach? I would need the security container in my entity. What is your approach to this?
How to check for related entities:
Extending my previous example, I have a Group and this group can hold some appointments. In my actions where the appointments are shown or edited, I only want to check for the group. This is mainly for using the "view" rights. Meaning if someone is in the Group which holds the appointment, the person should also be able to view the appointment. I would like to implement this with JMSExtraSecurityBundle and SecureParam, but I have no Idea how to do that.
I want to create a relationship between a custom table (Websites) and the default aspnet tables related to Users.
I'm using code-first so for most FK relationships I would just do
public ModelName ModelName { get; set; }
With this, EF will automatically create the FK relationships. Very easy.
What's confusing is the most effective way to hook into the aspnet users/membership table. Do I create a new model Users that acts as an interface so that I can implement custom user code?
Is there a best way to do this that fits well into EF best practices? I basically just want to relate a user to the Websites table/model so that EF can do its thing.
"Do I create a new model Users that acts as an interface so that I can implement custom user code?"
If you want flexibility, I would say this is the way to go. This way it would be easier if you wanted to change to some sort of different Authentication DB structure in the future.
For example, have an "AppUser" Entity where the corresponding table has a foreign key to the "UserID" column of the aspnet_Membership table. This way you can simply add properties to your "AppUser" Entity instead of trying to change the MS table structure (which can be a real pain). You can still interact with the built-in MS Membership classes and functions from your MVC project using something like the MvcMembership starter Kit DLL's.
https://github.com/TroyGoode/MembershipStarterKit
Hope this helps!
This has few preconditions:
ASP.NET tables must be in the same database as your own tables
Previous precondition means that you must either create your database and tables manually (without automatic code-first generation) or you must use some custom initializer which will add non mapped ASP.NET tables as part of database recreation
If you want your model class to have relation with ASP.NET table you must model ASP.NET table as another entity. I'm not sure if you can use ASP.NET classes for that because for example MembershipUser doesn't have parameterless public constructor which is required for EF. So you will most probably need to create duplicate classes and their mappings and use these classes when referencing ASP.NET entities.