I've made an application in ASP.NET MVC. I first created an database in SQL Server and then installed the Entity Framework in Visual Studio and used the Entity Data Model Wizard, I selected the 'Code First from database', and it generated the derived DbContext Class and the models from the database.
My question is basically, why is it called 'Code First' when all the classes are generated based on the database - I've basically written no code, apart from the SQL.
Normally Code first refers to generating the database from your POCO but typically when you are targeting an existing database you can have the VS tools create the classes for you to get up and running quickly.
That is the impression I go from typing Code First from database into google.
Code-First from an Existing Database:
Entity Framework provides an easy way to use code-first approach for
an existing database. It will create entity classes for all the tables
& views in your existing database and configure it with
DataAnnotations attributes and Fluent API.
Additional source:
ScottGu's Blog - Using EF “Code First” with an Existing Database
EF “Code First” works great with existing databases, and enables a
very nice code-centric development approach with them. In particular,
it enables you to use clean “plain old classes” (aka POCO) for your
model objects, and cleanly map them to/from the database using either
the default mapping conventions or by overriding them with custom
schema mapping rules.
Related
We have some ASP.NET webforms applications, and we want to migrate to ASP.NET MVC 5 and Entity Framework.
We have a lot of stored procedures in SQL Server, so we need to call them in from the ASP.NET MVC application.
The question is: which one is more suitable?
Entity Framework database-first
Entity Framework code-first
Although this is strongly biassed and opinion based:
I would go for code first: always... (well.. except if the application is on the end of it's lifetime)
As for your stored procedures; you can add them by applying a custom migration.
2 of the main benefits:
no tooling dependencies (diagrams and such) (in the past these could be slow)
no manual touching the database and full configuration by code (so the code is always right)
Since it's a migration; you might want to generate your code first code based on an existing db.
Use SQL Server database project to manage your schema, and DB First with EF.
Let's say I am developing a few ASP.NET MVC applications working with data in an existing database just over by stored procedures, no and never linq to entities or anything else. That database contains lots of schemas and all my web applications needs the different schemas as well.
Here is my point:
I have a x.Model project in my solution that contains my ADO.NET Entity Model to create return types for all of my stored procedures in my existing db.
I have x.Repository.y projects in my solution where y is the schema name in the database. These projects contains classes having functions to call the stored procedures from the appropriate schema by ADO.NET Entity Model's context. So I have to have reference of x.Model in these repository projects.
And I have ASP.NET MVC projects that uses the necessary injected repositories from x.Repository.y projects. I use some of these return types of stored procedures as models in my views, so I need a reference to x.Model project too. But in that case this reference gives all the context to client web applications. I don't want my whole or partial db entities is reachable in my web applications. I just want them to know about necessary repository classes.
Is it possible? How can I do that?
If I remove x.Model project and create the ADO.NET Entity Models containing just the appropriate schemas stored procedures in my x.Repository.y projects then the referencing web applications again knows about this schema's whole db entities.
Thanks in advance,
Maybe, better way to use Model First or Code First approach. So, you can describe pure (without references to DbContext and other Data classes) entities. Then, create mapping in x.Repository project. And referene your Model to ASP.NET MVC site. So, you will have only entities and repositories but mapping and DbContext will be hidden inside one reference (you can mark mapping classes as internal).
Is there a way to create a model from an ado.net SqlDataReader? I would really prefer to use Asp.net MVC 5 coming from Ruby on Rails rather than Webforms, but I need a way to display the data from an existing database on the view. Or could I possibly do this without creating a model by handling this in the controller? I don't want to create a model based on column names in the table in case the table (or db schema) changes later on.
Use Entity Framework`s DbContext.
Looking around, the normal solution would be to reverse-engineer the model from the database found here: http://www.codeproject.com/Articles/671590/Reverse-Engineering-an-Existing-Database-in-your-A
Unfortunately, this is something that usually has to be done through Visual Studio, which I will not always have access to once the application is in production mode. If the schema changes, I would not be able to use the Update Model from Database... command in VS 2013. Therefore, I'll have to use Asp.net Web Forms for my Database-First application.
I have an MVC 4 app that I am working on and using the code first implementation except I cheated a bit and created my database first then generated my entity classes (poco) from my database using the EF power tools (reverse engineer). I guess you can say I did database first method but I have no edmx file just the context class and my entity classes (poco)
I have a few projects in the works using MVC and EF with pocos but just the one project I used the tool to generate my pocos from the database.
My question is about the mapping files that get created when I generate my pocos using the tool. What is the purpose of these Map files? I figured the map files are needed when generating the db from the model like with the true code first method, in my case where I am using a tool to generate my model from the database do the map files have any influence on how my app uses the entity classes?
The mapping files are to fluent files help Code First generate the database from your model, as well as help EF create the proper relationships.
They can map properties - things like setting a primary key, max length, data type.
They can also map relationships - set things like foreign keys, and defining relationships that don't follow standard CF naming conventions.
Even though you're not generating your database from the app, CF will use this system to ensure that the database it's pointing to is compatible with your model, and in the case of foreign keys and things setup related properties. For example, if you wanted to name a FK something other than NavigationPropertyId, you would need fluent to tell the engine what property to set in the database.
I need to use parameterized table-valued functions to retrieve the data for an association (the TVFs abstract the actual database tables), but would like to use all the good stuff provided by the EF. So looking at the generated Navigation Property code from the EDMX, I see that the RelationshipManager wraps the population etc. of the association.
So my question: can I retrieve the results I need from the DB (via the TVFs) and attach them to the context before the generated calls to the RelationshipManager, and also stop the RM itself from accessing the database?
EF4 does not support TVF. TVFs are available only in .NET 4.5 where you can use them in Linq-to-entities queries. .NET 4.5 also by default uses POCO entities which are now strongly recommended where RelationshipManager is not used inside the entity (except dynamic proxies for lazy loading).