It looks like Joomla MVC uses JTable as their ORM. Problem is that they can only handle one table and my application uses relational data.
Is it possible to use Joomla classes to map my Models to relational data or do I have to use a 3rd party for this (doctrine, propel)?
Not sure if this all makes sense because sometimes Joomla seems to use the JModel as a data provider (executing queries) and the JTable looks more like a model than JModel.
Related
I am using hibernate 3 using spring 3.5 for a SaaS application. I am expecting upto 10-15 customers , not more. I do not want to implement separate db or schema per customer as its too complicated and costly for a small enterprise like mine. I am currently using a multi-tenant strategy which works fine for a host of small features. Here is the use case where my design fails:
For reporting feature each customer will have a different table for data (because of various reasons like legacy, source of data etc). Table structure differs and so does service/controller behaviors.
I am currently planning to create separate Controllers, Services (DAOs), etc for each customer, thus mapping each of such customer tables with a separate hibernate class. But this approach is not clean and for every new customer I add (which is not that often though), I would need to add its table, and also code a hibernate entity class mapped to the new table, which is not ideal as it needs coding. Is there a way to manage/map such dynamic tables using hibernate which gets added when a new customer is added ?
Use Hibernate 4 multi-tenancy support, see the documentation here. There is support for separate databases per tenant, separate schemas per tenant and partitioning of the same table per tenant.
Is there a way to manage/map such dynamic tables using hibernate which
gets added when a new customer is added ?
I don't know if this is directly supported by Hibernate. From the manual, the supported multi-tenant options are:
schema
database
discriminator
Discriminator is mentioned but is not supported in the current release of Hibernate (version 4.2). That leaves schema and database. You mentioned in your question that neither of these are currently applicable to your setup. So unless you're willing to do some major restructuring, you'll probably need to proceed with a different approach.
Option 1:
If I were you, I'd write a view that presents the data from each tenant's table. You can add the tenant ID as a column in the view. Map the reporting class to the view with Hibernate. When you run a query against the view, set the current tenant's ID as a query parameter.
If you go this route, you won't need to add new controllers and POJOs when you add a customer. Just modify the view to also include the new customer's data and it should work.
Option 2:
Hibernate can bind native SQL query results to entities. You can have one entity that represents the data in any reporting table (this assumes that the separate per-customer tables have a similar structure).
In your reporting DAO, you'd fetch a SQL query from a properties file or specify a named SQL query based on the current tenant identifier. Note that the named query approach will only meet your needs (no recompilation of Java classes) if you have things mapped with HBM files. If your mapping is done with annotations, you'd need to rebuild the project to add a named query.
We are building an ASP MVC3 application, where we are building the service layer and Entity model. A third party is building Views/Controllers.
Now the tricky bit is the Model. Where should it go?
My opinion is the MVC web application will just have View and controller. Our service library will have business logic and EF. But I think we should not expose EF entities directly to the web application. (or should we? ) Instead we should look at the views and create view model classes for each views. This might require creating multiple view model classes for each view.
Can anyone provide their opinion on if this is right design? If so, where should view models reside? should we create another library just for view models?
I would suggest making your models as POCO objects with CRUD functionality- you shouldn't expose the EF entities. This way your service library can be reused in other applications or interfaces if needed.
If the POCO objects you provide won't work directly as view models, then it's up to the team writing the controller to create a view model from your service objects (POCOs). That would probably (hopefully) be a very simple view model, using your POCOs as properties (maybe a view model is a list of one of your POCOs, or a combination of a couple different POCOs).
That's just my two cents...
When developing with MVC with an ORM
I dont like the idea that the ORM will make changes in my DB.
My application is a data driven application and the DB is the the first thing i created.
Isn't that an overhead to maintain the data scheme both in the model and in the DB?
How do i manage it?
Any ORM that is more suitable to this kind of work method?
I dont like the idea that the ORM will make changes in my DB
ORM don't have to make any changes in your database structure. If you have existing database you can simply use it without requiring any automated changes.
Isn't that an overhead to maintain the data scheme both in the model and in the DB?
How do you want to present your data in MVC? Are you going to use classes representing your data from the database? If yes then you have a reason why ORM exists. ORM maps relational data from database to classes = it loads them for you and persists them for you (= you don't have to deal with database access and SQL). If you are going to use object oriented strongly typed approach then ORM will not be overhead for you.
If you are not going to use such approach you don't have to use MVC. Just use ASP.NET with SQL data sources or ASP.NET dynamic data.
Any ORM that is more suitable to this kind of work method?
You have no special method.
Almost every ORM has some support tools or extensions which allows you creating basic mapping and sometimes also classes from existing database. In EF you will simply add Entity Data model to your project and in wizard selects tables you want in your application.
Sure the last paragraph was simplified. Each ORM has learning curve and its specialties so it will not be so "simple".
For .NET 4 Entity Framework, the tooling let's you go both directions; generate a database from a model and generate a model from a database. These features give you flexibility when implementing your change management protocols. I'm not sure what options are available for NHibernate.
Entity Framework references:
http://msdn.microsoft.com/en-us/library/bb386876.aspx
http://msdn.microsoft.com/en-us/library/bb399249.aspx
http://www.simple-talk.com/dotnet/.net-framework/entity-framework-4460---learn-to-create-databases-from-the-model/
A Stackoverflow comparison of the two:
Deciding between NHibernate vs Entity Framework?
I've been using ASP.net MVC for about two years now and I'm still learning the best way to structure an application.
I wanted to throw out these ideas that I've gathered and see if they are "acceptable" ways in the community to design MVC applications.
Here is my basic layout:
DataAccess Project - Contains all repository classes, LINQ-to-SQL data contexts, Filters, and custom business objects for non-MS SQL db repositories (that LINQ-to-SQL doesn't create). The repositories typically only have basic CRUD for the object they're managing.
Service Project - Contains service classes that perform business logic. They take orders from the Controllers and tell the repositories what to do.
UI Project - Contains view models and some wrappers around things like the ConfigurationManager (for unit testing).
Main MVC Project - Contains controllers and views, along with javascript and css.
Does this seem like a good way to structure ASP.NET MVC 2 applications? Any other ideas or suggestions?
Are view models used for all output to views and input from views?
I'm leaning down the path of making view models for each business object that needs to display data in the view and making them basic classes with a bunch of properties that are all strings. This makes dealing with the views pretty easy. The service layer then needs to manage mapping properties from the view model to the business object. This is a source of some of my confusion because most of the examples I've seen on MVC/MVC2 do not use a view model unless you need something like a combo box.
If you use MVC 2's new model validation, would you then validate the viewmodel object and not have to worry about putting the validation attributes on the business objects?
How do you unit test this type of validation or should I not unit test that validation messages are returned?
Thanks!
Interesting.
One thing I do differently is that I split off my DataAccess project from my Domain project. The domain project still contains all the interfaces for my repositories but my DataAccess project contains all the concrete implementations of them.
You don't want stuff like DataContext leaking into your domain project. Following the onion architecture your domain shouldn't have any dependencies on external infrastructure... I would consider DataAccess to have that because it's directly tied to a database.
Splitting them off means that my domain doesn't have a dependency on any ORM or database, so I can swap them out easily if need be.
Cheers,
Charles
Ps. What does your project dependency look like? I've been wondering where to put my ViewModels. Maybe a separate UI project is a good idea, but I'm not entirely sure how that would work. How do they flow through the different project tiers of your application?
I have used the Entity Framework to start a fairly simple sample project. In the project, I have created a new Entity Data Model from a SQL Server 2000 database. I am able to query the data using LINQ to Entities and display values on the screen.
I have an Oracle database with an extremely similar schema (I am trying to be exact but I do not know all the details of Oracle). I would like my project to be able to run on both the SQL Server and Oracle data stores with minimal effort. I was hoping that I could simply change the configuration string of my Entity Data Model and the Entity Framework would take care of the rest. However, it appears that will not work at seamlessly as I thought.
Has anyone done what I am trying to do? Again, I am trying to write an application that can query (and update) data from a SQL Server or Oracle database with minimal effort using the Entity Framework. The secondary goal is to not have to re-compile the application when switching back and forth between data stores. If I have to "Update Model from Database" that might be ok because I wouldn't have to recompile, but I'd prefer not to have to go this route. Does anyone know of any steps that might be necessary?
What is generally understood under the term "Persistence Ignorance" is that your entity classes are not being flooded with framework dependencies (important for N-tier scenarios). This is not the case right now, as entity classes must implement certain EF interfaces ("IPOCO"), as opposed to plain old CLR objects. As another poster has mentioned, there is a solution called Persistence Ignorance (POCO) Adapter for Entity Framework V1 for that, and EF V2 will support POCO out of the box.
But I think what you really had in mind was database independence. With one big configuration XML that includes storage model, conceptual model and the mapping between those two from which a typed ObjectContext will be generated at designtime, I also find it hard to image how to transparently support two databases.
What probably looks more promising is applying a database-independent ADO.NET provider like the one from DataDirect. DataDirect has also announced EF support for Q3/2008.
http://blogs.msdn.com/jkowalski/archive/2008/09/09/persistence-ignorance-poco-adapter-for-entity-framework-v1.aspx
The main problem is that the entity framework was not designed with persistence ignorance in mind. I would honestly look at using something other than entity framework.