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.
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'm following the EF Code-First approach in a project that works against an existing database, to which I'm adding tables as needed.
This database has a number of tables for which I need to generate POCO classes for, and so I was wondering if there was a straight-forward, clean approach, to generating simple POCO classes from the database ... from which I can continue to work with using the general Code-First paradigm?
You can use the Entity Framework Power Tools for that.
If you want just the simple Poco classes without any relations use this T4 template
Generate entity class from database table
EF and ORM.
I recently realized that is possible using POCO to have clean classes not plumbed with EF auto generated code.
I saw the new release of EF 4.1 and the use of Code First approach and DbContext.
My questions:
What is the difference between Code First approach and Poco approach?
Can we use Code First (DbContext and DbSet) instead of POCO + Repository pattern?
Thanks for your time on this.
They're completely different things, and you can use them together.
POCO means that your entity classes are "normal" classes, not dependent on any specific ORM layer.
A DbContext is an object that enables you to access the database in an object-oriented way (like ObjectContext in earlier versions of EF).
Have a look at this tutorial for examples.
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.