I have a Database , and I am proceeding with EF DB first approach .
Right click on Model folder
--> select new item
-->ADO.net Entity Data model.
then selecting the DB & finally clicking Finish.
After that I am not getting the Model Diagram of my DB. Not getting any Diagram for any of the tables.
The Default view is ADO.net Entity Data model Designer
Where is the issue? EF version is latest Stable(6.1.3).
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Did you select the tables?
https://magnusmontin.files.wordpress.com/2013/05/wizard2.png?w=590&h=515
Or remove ef and then later add your project
Your answer is that your current version of the asp.net web application form's entity framework does not match the entity framework version while you create your DB first model
Related
I have one table in the database with the name "Users", a year ago one of the developers added a model using database-first approach, and I don't know which entity framework version they used.
Now i want to change some of the fields datatypes in SQL.
The problem is that I am not able to update model using the refresh window and also tried to delete model and add it again, but after that there was a name that has been changed in Users to User.
The current entity framework version is 6.1.3
Just go to your DataBase.edmx and right click "Update Model from Database..." and then refresh the tables
For the table name check link please -> What is the meaning of the "Pluralize or singularize generated object names" setting?
And Ricardo has already written the update.
My ASP.NET MVC 4 application uses Entity Framework 6 and a database-first approach. It is already in production environment, and now wants to add new column to the Deposit table and this column is not null. The production table already has a lot of data.
How should I manage this changes, in code-first approach, can anyone help me out? What should I do, I am new to Entity Framework.
If you will continue to use the database-first approach you can do something like that:
1) run a script to migrate DB:
ALTER TABLE Deposit ADD <column_name> INT NULL
GO
UPDATE Deposit SET <a valid not null values for your column>
GO
ALTER TABLE Deposit ALTER COLUMN <column_name> INT NOT NULL
GO
2) Since you are using the db-first approach you need update edmx model (.edmx file) which is already attached to db. If I remember correctly, you can do it from context menu in Solution Explorer.
I'm wondering if this is even possible. I'm writing an app in MVC using ASP.NET Core and EF Core. For the most part I've been doing code-first migrations (that's all I know how to do, as yet) for my entities.
Someone added a table to the database I'm using, and rather than deleting their table and doing it the code-first way, I'd like to just bring their table over using a DB first migration.
Is that even possible to mix and match DB-first/code-first techniques?
If it is, how do I do it? I can't seem to find anything about bringing over just one table. Only migrating a whole database, which is not what I want.
Yes, it's possible. The steps are the following:
Right click on your Models folder.
Select Add -> Add new Item
In the Add New Item Window, select Data -> ADO.NET Entity Data Model. (This would create a new DbContext, but we going to merge the two DbContext) Click Add
In the Entity Data Model Wizard select Code First from database.
Select your connection String.
Click in no, exclude sensitive data...
Uncheck Save connection settings.
Click next
Select the new Table
Click finish
In this point VS would generate two files: a new DbContext and the model for the table.
Now open de new DbContext cut the DbSet of your model and paste in your original DBContext, too cut the content of the OnModelCreating method and paste at the end of the OnModelCreating method of your Original DbContext.
The final step is add a new Migration ignoring the changes.
For example:
Add-migration NewTableAdded -IgnoreChanges -verbose
Environment : EF 6, SQL 2012
Setup: Database First, LazyLoading disabled
The question might appear more generic but will try to explain it in the best possible way.
I have a large application using ASP.NET MVC and grouped the entity based on the logical functionality. Hence we built multiple EDMX files
There is scenario in which we have to use the similar entity in two EDMX file.
School has relation to Teachers and Students.In first EDMX file, i used school and Teachers.In Second EDMX file, i used school and students
But only one Entity class getting created. If i run the custom tool on second EDMX context file, then the entity(school.cs) on my first edmx getting disappeared and it appears on the second one..
Why this strange behaviour occurs?
Here is the code in my first EDMX file
As you see here, i m not accessing school entity and also i disabled Lazyloading. But it complains that it couldnt find school file. Note: Courses has navigation property to school. But i didnt include it here.. Why its occuring so?
var courses= DB.courses
.AsNoTracking()
.Select(e =>
new CourseDTO()
{
CourseID= e.CourseID,
Name= e.CourseName,
Desc= e.Desc,
isActive= e.isActive
})
.OrderBy(e => e.CourseID);
The problem is, I m able to include one entity in the EDMX file only..
In first EDMX, it has navigation property to Teachers
In second EDMX , it has navigation property related to Students. But only Entity file exists at a time.. With only one Entity file, the code breaks
Note: This is just sample..Not my original application
Thanks #GertArnold. Meanwhile, i tried to create folders and kept the EDMX file inside it. Means i created seperate folder for each logical group and then included edmx file inside it. This in turn made the edmx file entities have different name space(i mean the entity classes) and also it enabled to have the same entity across multiple EDMX files. It sounds to have resolved my problem.
I didnt try to have them included under different namespace.. The whole idea started when i realized that even though i have two EDMX files, the associated entities(.csfiles) are created in the same physical location. I tried to create sub folders and included the EDMX files. It resolved the problem and i found it is having different name space
:):)
So I have a database and have created a model from it. Everything works just fine. But now I want to add more tables to my database and produce models from them.
Is that possible with EF Database first? Do I have to recreate all models for it to add new ones? All tables are of course from same database.
Example:
Let's say I have Table1, Table2, and Table3.
And by using DBContextGenerator in VS I've generated models from .edmx file. So I'd have Model1, Model2, and Model3 for corresponding database tables, and I'd like to add Table4 and Model4.
Do I have to recreate everything or is it possible to add somehow?
Open up your .edmx in design view.
Right click in there somewhere and choose "Update Model from Database".
On the "Add" tab, expand "Tables", and find your new database tables.
Check them, and click finish.
I've done this regularly as the DB changes and tables are added during development, it's been very reliable.
To generate the classes, do the following:
Right click on the .tt file of the solution explorer.
Click on the "Run custom tool".
Click on "OK" for the warning.
new classes will be generated.