NPGSQL relation "Blog" does not exist - entity-framework-core

Question

I'm trying to set up entity framework core for a project and i'm working through the entity framework core guide on the NPGSQL site: https://www.npgsql.org/efcore/index.html
and i'm getting the following error:
Microsoft.EntityFrameworkCore.DbUpdateException
HResult=0x80131500
Message=An error occurred while saving the entity changes. See the inner exception for details.
Source=Microsoft.EntityFrameworkCore.Relational
StackTrace:
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.Execute(IRelationalConnection connection)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute(IEnumerable`1 commandBatches, IRelationalConnection connection)
at Microsoft.EntityFrameworkCore.Storage.RelationalDatabase.SaveChanges(IList`1 entries)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(IList`1 entriesToSave)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(StateManager stateManager, Boolean acceptAllChangesOnSuccess)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.<>c.<SaveChanges>b__104_0(DbContext _, ValueTuple`2 t)
at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(Boolean acceptAllChangesOnSuccess)
at Microsoft.EntityFrameworkCore.DbContext.SaveChanges(Boolean acceptAllChangesOnSuccess)
at Microsoft.EntityFrameworkCore.DbContext.SaveChanges()
at Program.Main(String[] args) in C:\Users\brandp3.DTINET\source\repos\EF-ModelFirst\EF-ModelFirst\Program.cs:line 15
This exception was originally thrown at this call stack:
[External Code]
Inner Exception 1:
PostgresException: 42P01: relation "Blog" does not exist
POSITION: 13
here's the code:
static void Main(string[] args)
{
using (var db = new BloggingContext())
{
// Create and save a new Blog
Console.Write("Enter a name for a new Blog: ");
var name = Console.ReadLine();
var blog = new Blog { Name = name };
db.Blogs.Add(blog); // error thrown here
db.SaveChanges();
// Display all Blogs from the database
var query = from b in db.Blogs
orderby b.Name
select b;
Console.WriteLine("All blogs in the database:");
foreach (var item in query)
{
Console.WriteLine(item.Name);
}
Console.WriteLine("Press any key to exit...");
Console.ReadKey();
}
}
The model:
public class Blog
{
public int ID { get; set; }
public string Name { get; set; }
public virtual List<Post> Posts { get; set; }
}
public class Post
{
public int ID { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public int BlogId { get; set; }
public virtual Blog Blog { get; set; }
}
and the dbcontext setup
public class BloggingContext : DbContext
{
public DbSet<Blog> Blogs { get; set; }
public DbSet<Post> Posts { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseNpgsql("Host=localhost;Database=postgres;Username=postgres;Password=mysecretpassword");
}
}
From what I understand the tables and relations should be created when I first run the program. At least the guide doesn't indicate that I need to push the schema to the database

Answer 1

From what I understand the tables and relations should be created when I first run the program.
EF Core doesn't automatically create the database schema for you - if you read this somewhere, can you please point to where that is? You'll have to either use Migrations or EnsureCreated (though that's discouraged).
See also the EF getting started guide, where minimal migration creation is shown.