Is it possible to use the entity framework from a class library?

Yes, it is entirely possible to separate the project into class libraries

until you have a question here in SO-PT about performance

Example of how to split into projects:

In a blank solution create 3 projects, which are

i) ProjectName.Classes (here will be the project classes);

ii) DesignName.Entity (here will be entity settings)

iii) ProjectName.MVC (this will be the web layer)

In the classes layer, create a class, for example:

public class Pessoa
{
    public int PessoaId { get; set; }
    public string Nome { get; set; }
    public string Sexo { get; set; }
}

On the Entity layer, install the entity Install-Package EntityFramework from the package manager console or the nuget . Create a context class, for example:

public class EntitySeparadoDbContext : DbContext
{
    public EntitySeparadoDbContext()
    { }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //No exemplo está sendo usuário o EntityTypeCOnfiguration para configurar como ficará a classe no banco
        modelBuilder.Configurations.Add(new PessoaConfiguration());
    }

    public DbSet<Pessoa> Pessoas { get; set; }
}

Then you can enable migrations ( enable migrations ), add them ( add-migration <nome> ) and execute them ( update-database )

NOTE: You need to set the Entity project by default in the package manager console

Afterthat,intheMVClayeryoujustneedtoinstantiatethecontextanduseitnormally,eg:

privateEntitySeparadoDbContextdb=newEntitySeparadoDbContext();publicActionResultDetails(int?id){if(id==null){returnnewHttpStatusCodeResult(HttpStatusCode.BadRequest);}Pessoapessoa=db.Pessoas.Find(id);if(pessoa==null){returnHttpNotFound();}returnView(pessoa);}

Imadeanexampleprojectanduploadediton GitHub

Maybe you also want to see about:

How to implement the Repository Pattern in C # with EF?