Entity Framework Fluent API Discover How to Map Without Annonation

When working with Entity Framework Code First the default behavior is to map your POCO classes to tables using a set of conventions baked into EF.

• Fluent API specify the model configuration that you can with data annotations as well as some additional functionality that can not be possible with data annotations.
• We can configure many different things by using it because it provides more configuration options than data annotation attributes.
• Data annotations and the fluent API can be used together, but precedence of Fluent API > data annotations > default conventions.

DbModelBuilder

DbModelBuilder is typically used to configure a model by overriding DbContext.OnModelCreating(DbModelBuilder) .

You can override the DbContext.OnModelCreating method and use a parameter modelBuilder of type DbModelBuilder to configure domain classes.

Key

You can use the HasKey() method to configure the name of the primary key constraint in the database.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Author>()
        .HasKey(a => a.AuthId);
}

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Concurrency Token (ConcurrencyCheck)

You can use the IsConcurrencyToken() method to configure a property as a concurrency token.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Author>()
        .Property(a => a.LastName)
        .IsConcurrencyToken();
}

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Exclude Types or Properties

You can use the Ignore() method to exclude a type or a property from the model.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Author>()
        .Ignore(a => a.IgnoreProperty);
}

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Required

You can use the IsRequired() method to indicate that a property is required.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Author>()
        .Property(a => a.LastName)
        .IsRequired();

    modelBuilder.Entity<Author>()
        .Property(a => a.FirstName)
        .IsRequired();
}

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Table Mapping

You can use the ToTable() method to configure the table that a type maps to.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
     modelBuilder.Entity<Author>()
        .ToTable("AuthorsData");
}

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Column Mapping

You can use the HasColumnName() method to configure the column to which a property is mapped.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Author>()
        .Property(a => a.AuthorId)
        .HasColumnName("Author_Id");
}

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Foreign Key

You can use the HasForeignKey() method to configure the foreign key constraint name for a relationship.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Book>()
        .HasRequired<Author>(b => b.Author)
        .WithMany(a => a.Books)
        .HasForeignKey<int>(b => b.AuthorId);
}

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Default Schema

You can use the HasDefaultSchema() method to specify a default schema.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.HasDefaultSchema("Admin");
}

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Index

You can use the HasColumnAnnotation() method to configure the name of an index.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Author>()
        .Property(a => a.Email)
        .HasColumnType("VARCHAR")
        .HasMaxLength(450)
        .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute("Index_Email") { IsUnique = true }));
}

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