On a .NET application we could auto generate .edmx file from database and can see its diagram by double clicking on that .edmx file. Now my question is since .NET Core does not allow to generate .edmx file then how i can see database diagram visually like the picture bellow? Is there any valid way to do it on .NET Core?
Whats the diff between class diagram and database diagram?
Technically that's a diagram of your Conceptual Model, the Edmx file contains the Conceptual Model, and explicit mapping metadata to map the Conceptual Model to a Storage Model on one side, and an Object Model on the other side. EF has since moved away from the explicit mapping in the .Edmx and uses a combination of Conventions, Fluent Configuration and Class Annotations to generate the mapping at runtime. This is called "Code First", although in practice you often generate a "Code First" model from an existing Database.
In EF6 Code First the Conceptual Model and Storage Model still technically exist, they are just generated at runtime from your Object Model. In EF Core one of the main design goals was to remove the limitations and complexity of this older 3-Model design, and the Conceptual Model (which is what the design surface of an EDMX displays) is gone altogether. No Conceptual Model, no .Edmx, no graphical designer.
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I am going through an old project code in visual studio 2013. And wondering if there is a way I can definitely say whether this project is "Model First" or "Database first"?
Please refer below picture (not sure what else to provide):
Update:
I appears I did not clarify what I wanted to establish. I make another attempt. Basically as I understand when you add a new model using "Entity Data Model Wizard", you can choose Database First ("EF designer from database") or Model First ("Empty EF designer model"). At this time, we know whether we created database first or model first BUT
Is it possible to tell looking at an existing code base?
I did as suggested by Tieson T. and choose "Empty EF Designer model" and click Finish. I got a Model1.edmx file. I am assuming what I did was a Model First approach. So I still have a .edmx file which is there in my existing project (which in answer he suggest is a database first approach). I followed this link msdn.microsoft.com/en-us/data/jj205424.aspx.
It may not be an important question but I am asking out of curiosity.
Update 2:
I did created two models using both approaches and this is what it looks in VS:
I noticed a .sql file I generated from model. Is it an indication?
Yes. .edmx files are only used by the database-first template. You can test this by generating one of each of the available templates.
You can also read the MSDN documentation:
The Entity Data Model Tools are designed to help you build Entity Framework applications. With the Entity Data Model Tools you can create a conceptual model from an existing database and then graphically visualize and edit your conceptual model. [...] The tools generate or modify an .edmx file, which contains information that describes the conceptual model, the storage model, and the mappings between them.
I have 20 class.cs with x00s properties for my old project
and now i want to use EntityFramework
but I dont want to rewrite all this classes from begin
i just want to convert this class to DataModel.dbml or use some thing like add Existing Item
and I tried creat class with same name and copy the code inside them but the editor clear them after saving
how can i do that ?
There is plenty of resources regarding Plain Old CLR Objects and Entity Framework code first model on the web.
ADO.NET EF 4.0: Working with Plain Old CLR Objects (POCO) Classes
Code First step by step tutorial
But the gist of it is:
Entity Framework >4.0 supports POCO types that don’t need to inherit from a base class or
implement any interfaces to get persistence. There is also no need for metadata or mapping
attributes on type members, so you can use your existing code as simple entity classes.
An EDMX file that contains the conceptual model is still required. Add a new ADO.NET Entity Data Model to the project.
Using the toolbox, drag entities and associations from the toolbox and design the conceptual model. Simply make sure that the names on your POCO classes match the names of your conceptual entities.
Add entity keys as you would add primary keys in a db. Add associations like foreign keys in a db.
In Solution Explorer, click the EDMX file and then, in the Properties window, clear the Custom Tool property to turn off the automatic generation of .NET classes for your conceptual model.
Right click edmx design area and select 'Generate database from model'. DDL will be produced. Run that to create your db.
Make sure your POCO classes and POCO edmx model are in a separate assembly.
Create your custom ObjectContext derived data context with ObjectSet<T> members like here. Newer EF releases use System.Data.Entity.DbContext and System.Data.Entity.DbSet<T> instead.
You can use dbml too (Linq To Sql classes instead of EF), but you still need to generate your model from scratch, like you'd do with EF.
I want to convert my code-first project to Database first. Is there an automated way or should I just delete the entities and context code and create a model from the created database?
It appears Entity Framework Power Tools supports a feature called "Reverse Engineer Code-First". You can download it here.
There is no way to convert your code-first classes into database-first classes. Creating the model from the database will create a whole new set of classes, regardless of the presence of your code-first classes.
However, you might not want to delete your code-first classes right away. The entity framework database-first model creates partial classes for all of the entity objects. If you have any business logic (anything besides the plain old properties) in your code-first classes, you can declare them as partial, remove the properties, and maintain the business logic. Essentially, you're letting EF generate the properties in the *Designer.cs file, while you define the business logic in your .cs files.
Maybe its just me but I am not a big fan of using the DBContext Generator as it adds overhead to development.
I like using the Entity Framework DBContext API but want to get rid of the hand coding of POCO classes. I am wondering if there are any T4 templates out there that can connect to MySQL or SqlServer and Generate the POCO classes from the database. Using the DBContext Generator template you have to update your database, update your model, re-run the T-4 templates to generate POCO classes. I would like to cut the steps down so that I don't have to generate and maintain a model.
Are there any T4 alternatives to the DBContext Generator that create the POCO classes and don't require an edmx model file?
There was alternative in EF Power Tools CTP1 but that is far away from power of DbContext Generator. Moreover those generations features from power tools were only for initial class generation. It didn't include any possibility for updates once you do any changes in the database.
You have probably missed point of DbContext generator. This generator creates classes from mapping defined in EDMX. It is very easy to use - it has just single additional step with updating model. If you have model and T4 template in the same project you will even not need to regenerate classes yourselves - it will happen automatically once you save changes in EDMX (so it will be only two steps).
What you are looking for would still have two steps (updating model and running the template) so the difference is "none". What you are looking for would not provide any significant boost to your process. It will only make all mapping more complex because you will have to hardcode it into template - that is also reason why such template probably doesn't exist.
I've begun experimenting with LINQ to SQL and what I am doing is basically creating classes with LINQ mapping decorators - thereby choosing which parts of the db table schema I want to incorporate into my classes.
A simple example:
private DateTime? _LocalCopyTimestamp = (DateTime)SqlDateTime.MinValue;
[Column(Name = "recaLocalCopyTimestamp", Storage = "_LocalCopyTimestamp", CanBeNull = true)]
public DateTime? LocalCopyTimestamp
{
get
{
return this._LocalCopyTimestamp;
}
set
{
this._LocalCopyTimestamp = value;
}
}
I am not using and am not willing to resort to modeling tools due to project contraints (the way schema changes are handled and because there is an existing database schema and it is a bit too organic and non-strict)
Is there a way to have this flexibility with the Entity Framework without having to include schema information files and/or lots of distinct code files?
Could I then also create classes that "use" more than one underlying table?
Can anyone point me to documentation regarding this?
The feature you are requesting (write C# classes and generate your model from those) is termed by the Entity Framework team "Model First." It does not exist in the current, shipping version of the Entity Framework, but is a planned feature for the next version. If you watch the Entity Framework talks from PDC, you can see demonstrations of this new feature. With the current version, you do not have to write "many" mapping files, but you do need one (the EDMX file), and it must be XML.
Yes, you can create entity classes which use more than one underlying table. This is called "Entity splitting." Step-by-step instructions at the link. In general, you will find that the Entity Framework supports many more complicated mapping scenarios than LINQ to SQL.
I'm afraid that I have to completely disagree with Marc regarding writing EDMX without use of the designer. Writing EDMX without using the designer is not only possible, but for projects exceeding a certain side, it is all but inevitable. A few points on this:
For most of the early history (pre-RTM; "ObjectSpaces") of the Entity Framework, writing the XML files manually was the only way to use the tool. The designer is a recent feature, and is considerably less stable than the Entity Framework itself.
There are certain Entity Framework features, such as complex types, which are not supported in the designer at all.
Certain mapping scenarios, such as not mapping individual columns, or mapping tables without a foreign key relationship, which may be necessary for legacy databases, are not supported in the designer.
As I mentioned in (1) the designer is quite a bit buggier than the Entity Framework itself. So on larger projects you will probably end up having to clean up after the designer's mistakes.
Entity Framework uses the EDM to model data; this is a set of 3 complex schema files (storage, conceptual, mapping), most commonly stored as resources in the project (via the designer which uses a single EDMX file to generate all 3 schema files).
It doesn't support attributed classes for this information. The only sensible way to write EDM is via the designer (essentially, a modelling tool which you dislike).
Re classes the "use" more than one underlying table; yes, a single Entity Framework entity at the conceptual layer (i.e. classes) can span multiple storage tables. This is especially useful for some inheritance examples, but can (IIRC) be used by flat models too. You do this via the "mappings" between the storage and conceptual layers (most commonly; on the tab in the designer).