The old Entity Framework Power Tools extension used to generate the Code First Domain classes and mapping classes (which used the Fluent API for constraints etc).
I favour the use of mapping classes over data annotations as you have cleaner models.
The Visual Studio wizard which reverse engineers a domain from a database uses a combination of Data Annotations and fluent code in the Model event handler.
This is nowhere near as clean.
Does anyone know if there is a tool which reverse engineers a database in the same way as the Entity Framework Power Tools?
Thanks
Yes, the "Ef Reverse POCO template" favors fluent configuration: https://marketplace.visualstudio.com/items?itemName=SimonHughes.EntityFrameworkReversePOCOGenerator
Related
I am new to entity framework and MVC, and trying to understand what constitutes a good design approach for a new application.
There are several ways of using Entity Framework. However, for my project, the best looking option is DB First. I've played around with an EDMX file, and I have got as far as using the DbContext code generator to create my wrapper classes.
I plan on using the repository and unit-of-work patterns, and using ninject for DI.
However, it does not seem "proper", from a SoC point of view, that whilst my respository will hide the implementation of the data store (EF) from my code, the model classes themselves are very much EF flavoured.
It seems that using EDMX-based approaches to EF blur the separation of concerns. Only POCO support seems to allow a true separation, but POCO has some other limitations that I don't like.
Am I missing something, or does using EDMX have this drawback?
Are people using an auto mapper to convert between the entity model and another, clean, SoCced model?
thanks
Tian
I don't have a strong opinion on the Separation Of Concerns question, but I have used both the standard ADO.Net version of EF and POCO and it is not difficult at all to customise the output of the the T4 code generation script for POCO to address any concerns you have about the structure of the objects created. That sounds like it would probably be a good starting point for what you are looking to do.
Once you know you are looking for T4 templates there are quite a few tutorials and a lot of helpful SO questions that can give you an idea of what you need to do.
I guess that EF4.1 is recent to EF4.0, but I didn't find any book on EF4.1, but 2 books on EF4.0.
can I still buy the book on EF4.0 expecting that I will get most of the concept??
Thanks for helping.
According to The ADO.NET Team blog, there are two main features:
The DbContext API is a simplified abstraction over ObjectContext and a number of other types that were included in previous releases of the ADO.NET Entity Framework. The DbContext API surface is optimized for common tasks and coding patterns. DbContext can be used with Database First, Model First and Code First development.
Code First is a new development pattern for the ADO.NET Entity Framework and provides an alternative to the existing Database First and Model First patterns. Code First is focused around defining your model using C#/VB.NET classes, these classes can then be mapped to an existing database or be used to generate a database schema. Additional configuration can be supplied using Data Annotations or via a fluent API.
EF 4.0 books are good unless you are using one of those 2 features, because you won't find them in there.
But you have plenty of resources online about those new features (especially Code First).
You even have official tutorials:
Using DbContext
Code First walkthrough
It seems that most of the focus with MVC3 and EF4.1 is around "code first" - I can't seem to find any examples or tutorials that meet the following criteria:
uses an existing SQLServer database
has separate projects for web & data access (we will have multiple web apps sharing the same data access classes)
recommendations for validation
Does such an example or tutorial exist? Are there any documented "best practices" for how to accomplish this, or rationale for NOT having a solution structured this way?
It is quite common scenario and it depends if you want to use EDMX file for mapping or if you want to have mapping defined in code (like code first).
Both scenarios can be done as database first
You will create EDMX from existing database with build in EF tools in Visual Studio and you will use DbContext T4 generator template to get POCO classes and DbContext derived class
You will download EF Power Tools CTP and you will use its reverse engineering feature to generate code mapping, POCO classes and context for you
Neither of these approaches will add Data annotations. Data annotations on entities should not be used for client validation (that is bad practice) unless you are doing very simple applications. Usually your views have some more advanced expectations and validation in view can be different then on entity. For example insert view and update view can need different validations and it is not possible to perform it with single set of data annotation on the entity. Because of that you should move data annotations for validation to specialized view models and transform your entities to view models and vice versa (you can use AutoMapper to simplify this).
Anyway it is possible to add data annotations to generated classes via buddy classes but as mentioned it is not a good practice.
Is there a template or tool to generate code from the database directly? I want to use model first scenario but do not want .edmx file for mappings. There is a database with many tables and I do not want to write all the classes (I am lazy) for that. So, is there a template to generate the code and set the annotations/use fluent api for defining the relationships, etc automatically from the existing database?
This would be helpful in the following scenario as well. Say, I was using .edmx with POCOs and now I do not want the mappings in the .edmx file. I want the mappings in the code. It would be great to have a tool or a template to generate the mappings in the code from the existing database.
I am starting on learning EF 4.1. I think "Code first becomes model first in version 2 i.e. after the database is created/released (in version 1) and needs some changes". Is that really true? I'd love to hear some comments. Thanks.
Check out the 'Reverse Engineer Code First' feature of the EF Power Tools CTP1 that was just released.
For generating classes, you can use POCO t4 template generation. Have a look at this detailed link which will help you getting started. That way you will get all the classes generated.
For mapping, you can use Code-Only style for Entity Framework but generating classes and context using POCO template will have far more advantage over creating the mapping yourself. Imagine adding new tables or modifying the tables, it will involve more work. But I will certainly love to know if there is any mapping tool for that.
It is possible that you are using EF-provider Devart dotConnect for Oracle when working with Oracle database. In this case the following information will help you to choose the tool.
The first version of Entity Framework Power Tools also contained the capability of generating a Code-First model with fluent mapping from an existing database. Although useful, this functionality is limited as regards its flexibility: the developer can only set the connection string; following that, classes are generated from all database objects available to the user. That is not extremely convenient, since in Oracle, for example, numerous schemas containing hundreds and sometimes thousands of tables are available to the user.
Rather than resort to this limited functionality, the users of Devart ADO.NET providers can avail themselves of impressively robust design-time development capabilities of Entity Developer, an EF-designer delivered with Devart providers. Also possible is the choice between the Database-First approach, as provided in EF Power Tools, and the Model-First approach, within which Code-First classes are created in the EDM-designer.
When compared to EF Power Tools, the Database-First approach to the development of EF Code-First models also allows selecting objects that must be available in the model, setting naming rules for the generation of class names and properties and so on. Besides, the resulting model can be modified and improved in the designer.
To better meet developers' needs, Code-First code generation in Entity Developer both for C# and VB is based on the T4-template that is easily accessible and can be modified in feature-rich T4 Editor contained in Entity Developer.
For more information on Code-First development in Entity Developer, see "Entity Developer – EF Code First DbContext Template"
http://www.devart.com/blogs/dotconnect/index.php/entity-developer-ef-code-first-dbcontext-template.html
I currently generate XML from my single source of truth and save it as an Entity Framework EDMX file and then use the EntityClassGenerator object to create the classes from the diagram. Is there a way to generate the classes without having to create the XML file first?
I haven't heard back from Ladislav Mrnka, so I'll put his comment here as an answer. Using the Entity Framework's new Code-First, I can have a code-centric development workflow where my generator will create POCOs and a custom DbContext, then my database will be generated from the POCOs using convention instead of configuration. No need for an EDMX at all!
Here's a good explanation of it: http://weblogs.asp.net/scottgu/archive/2010/12/08/announcing-entity-framework-code-first-ctp5-release.aspx
EF needs the metadata from the EDMX at runtime. Even if you could use CodeModel or something to generate the entity classes, they would be useless to the EF runtime without the metadata describing the storage model, mapping etc.
Fabio Scopel has a webcast on youTube where he shows this Beta Tool (back then) called Entity Framework Reverse Engineer.
Check the link Entity Framework 5.0 - Code First Reverse Engineering existing DataBase