I am getting into the Entity Framework, but I am unsure if I am missing a critical point in the code-first approach.
I am using a generic repository pattern based on the code from https://genericunitofworkandrepositories.codeplex.com/ and have created my entities.
But when I try to access or modify the entity I run into the following:
System.InvalidOperationException: The entity type Estate is not part of the model for the current context.
It happens when I am trying to access it from my repository:
public virtual void Insert(TEntity entity)
{
((IObjectState)entity).ObjectState = ObjectState.Added;
_dbSet.Attach(entity); // <-- The error occurs here
_context.SyncObjectState(entity);
}
The database (./SQLEXPRESS) is created just fine, but the entities (tables) is just not created on startup.
I am wondering if I need to explicit set the mapping of the entities? Is EF not able to this by its own?
My Entity is:
public class Estate : EntityBase
{
public int EstateId { get; set; }
public string Name { get; set; }
}
My context is as so:
public partial class DimensionWebDbContext : DbContextBase // DbContextBase inherits DbContext
{
public DimensionWebDbContext() :
base("DimensionWebContext")
{
Database.SetInitializer<DimensionWebDbContext>(new CreateDatabaseIfNotExists<DimensionWebDbContext>());
Configuration.ProxyCreationEnabled = false;
}
public new IDbSet<T> Set<T>() where T : class
{
return base.Set<T>();
}
}
Is there any specific reason why this error occurs? I have tried enable migrations and enable automatic migrations without any help either.
Put this in your custom DbContext class:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Estate>().ToTable("Estate");
}
If your tables are not created on startup, this is why. You need to tell the DbContext about them in the OnModelCreating method override.
You can either do custom per-entity mappings here, or separate them out into separate EntityTypeConfiguration<T> classes.
Apparently, this error is very generic, it could have a number of reasons. In my case, it was the following: The connection string (in Web.config) generated by the .edmx was invalid. After almost a day of trying everything, I changed the connection string from the EF string to an ADO.NET string. This solved my issue.
For example, the EF string looks something like this:
<connectionStrings>
<add name="BlogContext"
connectionString="metadata=res://*/BloggingModel.csdl|
res://*/BloggingModel.ssdl|
res://*/BloggingModel.msl;
provider=System.Data.SqlClient
provider connection string=
"data source=(localdb)\v11.0;
initial catalog=Blogging;
integrated security=True;
multipleactiveresultsets=True;""
providerName="System.Data.EntityClient" />
</connectionStrings>
And the ADO.NET string looks like this:
<connectionStrings>
<add name="BlogContext"
providerName="System.Data.SqlClient"
connectionString="Server=.\SQLEXPRESS;Database=Blogging;
Integrated Security=True;"/>
</connectionStrings>
For me the issue was that I had not included the Entity Class within my db set inside the context for entity framework.
public DbSet<ModelName> ModelName { get; set; }
The problem may be in the connection string. Ensure your connection string is for SqlClient provider, with no metadata stuff related to EntityFramework.
You may try removing the table from the model and adding it again. You can do this visually by opening the .edmx file from the Solution Explorer.
Steps:
- Double click the .edmx file from the Solution Explorer
- Right click on the table head you want to remove and select "Delete from Model"
- Now again right click on the work area and select "Update Model from Database.."
- Add the table again from the table list
- Clean and build the solution
I've seen this error when an existing table in the database doesn't appropriately map to a code first model. Specifically I had a char(1) in the database table and a char in C#. Changing the model to a string resolved the problem.
One other thing to check with your connection string - the model name. I was using two entity models, DB first. In the config I copied the entity connection for one, renamed it, and changed the connection string part. What I didn't change was the model name, so while the entity model generated correctly, when the context was initiated EF was looking in the wrong model for the entities.
Looks obvious written down, but there are four hours I won't get back.
My issue was resolved by updating the metadata part of the connection string. Apparently it was pointing at the wrong .csdl / .ssdl / .msl reference.
For me the issue was that I used the connection string generated by ADO.Net Model (.edmx). Changing the connection string solved my issue.
This can also occur if you are using a persisted model cache which is out of date for one reason or another. If your context has been cached to an EDMX file on a file system (via DbConfiguration.SetModelStore) then OnModelCreating will never be called as the cached version will be used. As a result if an entity is missing from your cached store then you will get the above error even though the connection string is correct, the table exists in the database and the entity is set up correctly in your DbContext.
Sounds obvious, but make sure that you are not explicitly ignoring the type:
modelBuilder.Ignore<MyType>();
map of the entity (even an empty one) added to the configuration will lead to having the entity type be part of the context. We had an entity with no relationship to other entities that was fixed with an empty map.
if you are trying DB first then be sure that your table has primary key
Visual Studio 2019 seems to cause this for me. I fixed it by generating the edmx model again in 2017.
来源：https://stackoverflow.com/questions/20688922/the-entity-type-type-is-not-part-of-the-model-for-the-current-context