I know this isn't the designed method of using EntityFramework but I have a much easier time designing the database in SQL Management Studio to create indexes, link foreign keys, etc... all visually. But I really want to use the automatic database updates for the future when deploying updates to customers.
I designed the original database in SQL Management Studio then created the EntityFramework code first from that database. But if I want to add another table so far, I end up dropping everything then regenerating the DB from SQL Management Studio. This has been ok for the first part of my framework development but now things are starting to get a little more complex.
I've tried to learn the code first mechanism but some of the more complex items have bit me and I don't have a lot of time to allot for this. I was hoping there was a hybrid way of designing in SQL Management Studio then utilizing the database deployment functionality built into EntityFramework.
I'm working on getting the POCO reverse generator running here but having some issues. Ultimately, I think that is the way I'll want to go. But I did find a temporary workaround with existing tools built into VS2019 until I get that tool working.
I made a copy of the name of the model because I had a custom initializing for the connection string.
Delete the model file
I right clicked the folder where the codefirst files are placed in my solution then add-new item
Select ADO.NET Entity Data Model and named id the same as the one in step 1
Select Code First from Database
Deselect saving connection string (it won't overwrite and the needed one is already in the app.config)
Select the tables to import
In my case I deselected the Pluralize object names
Finish
Update the master model file with the custom initializer
In the package manager console enter: add-migration (I'm assuming you already have migrations set up)
name the migration
add-migration [name in step 12] (this applies the migration)
It might seem like a lot of steps, but it's actually not. And so far with a couple of days of playing around with it, I'm not running into any issues.
Related
I'm trying to upgrade my app to ASP.NET Core 2, with EF Core 2 (and SQLite), in other words netcoreapp2.0. I followed the upgrade guide.
I also recreated migrations, and noticed the new ones are quite different from the ones I remember from 1.1 (different commands sent to the db, different syntax, etc). But my model is the same, and after generating migrations, everything compiles properly.
BUT, when I try to create the db programmatically using context.Database.Migrate();, or manually on the CLI using dotnet ef database update, I get
System.NotSupportedException: SQLite does not support this migration operation ('AddForeignKeyOperation'). For more information, see http://go.microsoft.com/fwlink/?LinkId=723262.
However, I don't use the AddForeignKeyOperation command anywhere in my solution (I searched for it). I searched my migration files, and they don't use that command.
I'm sure it's something basic, but I can't track it down. What could it be?
Turns out the problem was not deleting all migrations.
I had the "initial" migration, then migration1, migration2, etc. The initial migration is from the template, so it had Identity/roles/users/etc. So I left that one alone and deleted/recreated the other ones only (i.e. the ones with my domain model).
Well it turns out that when I deleted ALL migrations, and recreated them, I stopped getting that error.
That error is confusing and poorly worded, and has nothing to do with the problem. Hope this helps someone else.
The project I am working on is using Entity Framework 4.3 and data migrations to keep the schema up to date. Over the course of the project the migrations folder has grown and now has over 600 files. This is huge. We now have a binary which is over 12MB due to all the migration meta data.
I would like to collapse all these in to one migration and start again. My concerns are:
Is this possible or will it cause problems with the migration history if I remove migrations?
Are there any guides around describing how to do this?
First: I recommend that you keep your migrations in a separate assembly so they don't have to be published with the application. It could be a simple console app that applies the migrations or a winforms GUI that generates scripts. But there's no reason for it to be deployed with the app imo.
Second: Understanding that you'd be giving up the ability to roll back to previous versions, you could just exclude-from-project all of your prior migrations then generate a new one which should then be able to create a database reflecting your current model. That would serve as your new starting point. Remember that EF doesn't always generate code to do everything you want in a migration, so you might have some hand-written migration code in other migrations you'd need to pull in.
Not sure past versions, but if you are here looking for the same solution for EF Core. You should be able to just delete the ModelSnapshot and re-run your migration to create a clean sheet.
I'm using VS 2013 and SQL Svr 2012 and trying use EF to populate a gridview. As this is a very simple test, I have just one table with a key and a couple of data fields. The process of creating the model seems to work fine - it shows as expected in the designer view, the files are created in app_code, a bin folder is created with 2 dlls, and the config file is updated with a connection string and other entries.
When I try to select the "named connection" I get the error "Unable to load the specified metadata resource" and it talks about rebuilding the project to get the assemblies.
I've spent hours reading other cases like this and I can't understand:
Why this is happening when it was never a problem with VS 2010
How do I fix the connection string to point to the resources it wants. I'm totally lost with all the technical advice about fully qualified assembly names - nothing I try works.
How do I set some parameter to force the resources to be in the proper place? All the advice I've read doesn't seem to relate very well with VS 2013
I need to decide if I should just uninstall VS 2013 and use VS 2012. Currently, I'm using VS 2010 with ASP 4.0 and I'd like to move to ASP 4.5 and generally keep up with Microsoft technology. However, I don't have the skill level to deal with a VS release that is buggy. It seems to me that this EF execise could be due to a either a bug or some odd corruption on my computer - I'm trying to figure out which is the case. I installed VS 2013 Express and SQL Svr 2012 on a clean machine that had none of these tools in the past.
I'd really like to see someone who is very familiar with Visual Studio try to replicate my problem as it only takes a few minutes to do so:
In MS SQL Server, create a tiny DB with one table that has a primary key and a couple of data fields and populate with some test data - Call it TinyDB with TestTable1.
Using VS 2013 Express for Web, create an "New Web Site" with the option for "ASP Empty Web Site" using VB.
Add an ASP App_Code Folder containing an "ADO.Net Entity Data Model" and leave the name as "Model".
Generate the model from the DB and make a "New Connection" for "TinyDB" and using Entity Framework 6.0 and then select "TestTable1". Note the namespace is "TinyDBModel". Clicking "Finish" will generate several items in App_Code, other folders and also update web.config.
Add a web form called default.aspx and drag a gridview onto it. In design mode for the gridview, select "new data source" and then the "Entity" option (note name of EntityDataSource1 which appears in default.aspx). Click next and under "named connection" select "TinyDBEntities" - this is where mine gets the error "Unable to load the specified metadata resource".
Note that this exact exercise in VS 2010 works perfectly and produces a grid with the correct data displayed.
Unfortunately, the EntityDataSource control does not work with the latest version of Entity Framework, EF6. Hopefully the control gets an update in a future update version of VS or EF, but for now you can't use the two together.
There are a few solutions / alternatives:
Drop back to EF 5. In order to do this, delete the .edmx and .tt files from the App_Code folder, delete the EF assemblies from the Bin folder, and remove the references to EF from web.config. Then rebuild the site, add a new ADO.NET Entity Model and choose version 5 in the Choose Your Version dialog. Then delete the .tt files from the App_Code folder, open the EDMX diagam, right-click an empty spot and on the Properties Grid set Code Generation Strategy to Legacy ObjectContext. Then rebuild again, and it should work.
Use Model Binding. This is really the recommended solution. The Microsoft / EF team recommends people to stay away from the EntityDataSource control and only use it for Dynamic Data web sites, Model Binding is the preferred solultion. It's pretty clean and straight forward to use, and gives you a lot of control over your queries and object updates. For more info about Model Binding, check out: http://www.asp.net/web-forms/tutorials/data-access/model-binding/retrieving-data
I've been using EF 4.1 and the POCO template generator.
I love and hate EF. I love the time I save. I hate maintaining the EDMX file.
But while keeping the EDMX in sync with the database has been a challenge, I'm now overwhelmed by the POCO generator. Up until now, the POCO generator has created POCO's for me and kept the ClassObjects.Context.cs empty and non-conflicting.
After my most recent refresh I have had constant problems with "Amiguity between 'perseus.DataLayer.accounts' and 'perseus.DataLayer.accounts'.
I get this error for every POCO.
I'm on the edge of panicking as I recommended and owned the maintenance of EF. I've spent a couple days on trying everything from database refreshes to deleting all items from the EDMX file and reloading them from the database.
Nothing has made a difference. I have no clue what has suddenly changed from the last few months of relative stability. I'm seriously lost as to what I can do from here.
It looks to me like you have not disabled the code generation strategy. click on the designer background and check the properties tab, the first item is Code Generation Strategy. This should say None, and not Default.
Editing the edmx manually is difficult and error prone. I would suggest copying what you have off to another location then letting the tool regenerate the edmx for you. Compare the two.
I worked with some DB2 entities that I had to manually sync and had constant issues. The tool would clobber my changes and I would have to manually replace that with working code.
If at all possible, don't modify the edmx code yourself. If you must, make the changes, copy those off to a text file in the project for tracking/safe keeping.
I am using Code First Data Migrations and have my development database so built up that I really don't want to start fresh again. I had deleted an old table and cannot get EF to accept any model changes due to this lingering phantom table. How can I get a clean version of my database context based on the model that's currently in place? Any help would be greatly appreciated!
You could use a "Code Second" approach and reverse engineer the model from the database. A good way to do this is to use the Entity Framework Power Tools for VS to do the reverse engineering. Once it is installed just right-click the project and select Entity Framework > Reverse Engineer Code First and select the relevant database in the dialog. This will generate a model in the Model folder.
I usually do this in a dummy project and then copy the files across. The model generation is actually very clean and adds some nice features like initializing ICollections to a new List in the constructor which are sometimes left out of the original Code First model.
EDIT
Here is an article which outlines the process using EF with an Existing Database