I like the Code First approach, but often I would prefer a visual model. The edmx model is a lot friendlier and neater for modelling a 'data model' than VS class diagrams, so it would be nice to generate an edmx from the code first POCOs and start round trip engineering, seeing as it is possible to generate POCOs from the edmx model.
You can use this vs extension to generate edmx diagram from code first dbContext, its read only as of now (extension is only in beta) http://visualstudiogallery.msdn.microsoft.com/72a60b14-1581-4b9b-89f2-846072eff19d
If you generate a database from your POCOs, you can then add a new EF item to your project and have it generate the model from the database. It's a little roundabout but it works well. I use it to check that the relations in code first models actually match what I intended.
Related
Can a Model First approach in MVC be implemented by avoiding the UML designer file? In my previous company Entity Model was written in a Xaml file. Then we used to run a T4 template tool and then get an Edmx file by choosing Generate views option. This would create class file and SQL scripts for procedures, Table Valued Functions which we later execute in SQL server to create database.
I am confused whether its code first or model first approach as we had not used any diagram to create entity relation.
This is model first.
But IMO "model first" is a misnomer making it more confusing than it should. In fact, it's "mapping first". An object-relational mapper (ORM), like Entity Framework, always deals with three main components --database, object-oriented code and the mapping between these two. Any of these three parts can be created first.
The other flavors are "database first": first the database, then the mapping (edmx) then the code (running t4 templates) and "code first: first the code, then the mapping (conventions, data annotations, and/or fluent) then the database (migrations).
I know entity framework designer is used to create the classes of model-first approach and then we create the database by using that class. But in code-first appraoch, it is possible to create the custom classes, within that classes the database is created automatically. Then what is the difference between code-first approach and model-first approach?
Code First is the more modern style of working with Entity Framework. As the name implies, you write the code first and the database model is generated for you, by using Entity Framework Migrations. In this scenario you are not using any graphical tool at all, everything is just pure code.
Model first means creating the abstract database model in the designer. The code is then generated by templates. If you update the model, the code will be regenerated.
I'm trying to figure out what the best way to go would be for Entity Framework code generation with a "database first" approach. I want the complete master description of the model to be the actual database schema with annotations stored in database in tables or extended properties. Not interested in a model first or code first approach. Not opposed to writing custom code to implement if it will yield the highest quality solution. Here are some ideas:
(1) Generate EDMX from the database. Use custom code to add annotations to the EDMX regarding uniqueness and other constraints that are not currently built in to EF. Use T4 templates to generate code from the EDMX.
(2) Write a custom tool that generates "code first" classes from the database. No EDMX files in the solution.
(3) Something else?
It seems like #1 requires deeper knowledge of EF and more actual work than #2, which I am now opposed to if there are significant benefits.
Any advice?
Well, nothing is easier than just dragging the tables from the server explorer to the edmx designer surface. That is how I do it. I don't do any customizations to the model so I can just delete parts of it an regenerate.
You can import the model from your database with EF. Right-click on the EF designer and choose "update model from database" option.
If you want a little more you can try http://radarc.net . It's a code generation tool which creates scaffolding and CRUDs. It uses T4 templates and code first so you can customize the way it generates code.
We are about to start using EF as our ORM. We have our own MetaData representing the databse stracture and we will generate whatever we need off of that.
We are wondering whether to use the "old" EDMX approace, or to use the new EDMX free approach (wiht DbSet and DbContext). As we do our own code/edmx generation it seems odd to generate an EDMX and then generate objects and context off of it.
The thing is I don't see much talk about about the EDMX free approach. Is it being used by anyone? Can someone with experience share their impressions? Are there known limitations? Are there pros and cons?
Asher
Are you asking if anybody is using code-first? :) By checking the number of questions in entity-framework-4.1 and code-first and ef-code-first I guess people are using it a lot. There were several questions about code-first x non code-first. Some of I answered:
EF POCO code only VS EF POCO with Entity Data Model
EF Model First or Code First Approach?
EF 4.1 Code-first vs Model/Database-first
Generally there are four approaches:
Model first (database generated from EDMX)
Database first (EDMX generated from database)
Code first (database generated from code mapping)
Database first with code mapping (code mapping manually created for existing database or manually updated mapping generated by EF Power Tools CTP)
Selection of the approach usually depends on the way how you want to develop application (as described in linked answers). It also depends if you want to use ObjectContext API or DbContext API. The former one is usually used with first two approaches (but the secret is it should work with code-first as well) the later one with all of them.
Code first has some limitations - it doesn't support all mapping features EDMX does for example:
Stored procedures mapping (it doesn't mean you cannot execute SP when using code first)
SQL functions mapping
Advanced EDMX features like defining queries, query views, model defined functions
etc.
What I don't understand is why are you trying to combine your code generation tool with EF. Either use your stuff or use EF's stuff. You will avoid complications and incompatibilities.
I am writing my first WPF and EF application. I am using SQL CE database and I have added few tables to the DB. The EF diagram is generated and now I want to generate the classes. I am new to EF and MVVM both.
When I right-click on a Table diagram, it gives option "Add Code Generation Item..". On selecting it, there are two options:
Add Entity Object Generator
Add Self-Tracking Entity Object Generator
I want to know what is the difference between the two. Which one should I use? I also want to know which one is latest and what is POCO?
A POCO is a Plain Old CLR Object... a simple class that has only properties.
http://en.wikipedia.org/wiki/Plain_Old_CLR_Object
There are 3 approaches that the Entity Framework delivers.
Model first (you create a model in visual studio and generate the database)
Database first (thats what you do, you generate a model from a existing database)
Code first (the newest one, you just write you POCOS and the entity framework generates the database)
I think it is enough to generate the diagram from database. The context and models should be available after this.
Neither of those is the POCO generator. The best way to get that is to install Entity Framework 4.1. You'll then see some new options in the list to add a code generation item.
I'm a pretty big fan of the DbContext/POCO generator added in 4.1 as the code it creates is VERY easy to work with compared to the older stuff, and it works well in a DB First setup like you're using (which is also what I use).
You can give this code generator a try:
http://salardbcodegenerator.codeplex.com/
It generates data annotations and implements INotifyPropertyChanged for CodeFirst approach.