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Entity Framework Core Model Configuration and Mapping

  • Article

Introduction

This article is for Entity Framework Core model configuration. By using this technique we can easily maintain the code and apply changes quickly.
 
Let's demonstrate how we can use assembly to dynamically initialize the generic classes.

Used Technologies

  • Entity Framework Core
  • Assembly (System.Reflection)

Step 1
Create a class with following properties:

public class  Person
{
    public int  Id { get; set; }
    public string  Name{ get; set; }
    public string  Gender { get; set; }
    public int  Age { get; set; }
}

Step2
Create entity configuration abstract base class

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
 
namespace EntityConfigurationBase
{
    public abstract  partial class  EntityCongurationMapper<T> : IEntityTypeConfiguration<T> where T : class
    {
        public abstract  void Configure(EntityTypeBuilder<T> builder);
    }
}

***Inherit entity configuration abstract base class

using DotnetCoreSamples.Domain.EntityModel.Blogs;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
namespace EntityConfigurationBase
{
    public partial  class PersonEntityConfiguration:EntityCongurationMapper<Person>
    {
 
 
        public override  void Configure(EntityTypeBuilder<Person> builder)
        {
            builder.HasKey(m => m.Id);
            builder.Property(m => m.Name).HasMaxLength(250);
          builder.Property(m => m.Gender ).HasMaxLength(20);
        }
    }
}

Step3
Create a context class and override OnModelCreating(ModelBuilder modelBuilder) method.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Internal;
using DotnetCoreSamples.Domain.EntityModel.Blogs;
using System.Reflection;
using DotnetCoreSamples.Data.Mapping;
using Microsoft.Extensions.Configuration;
using System.Configuration;
 
namespace EntityConfigurationBase
{
    public class  MyCustomContext : DbContext
    {
        public MyCustomContext()
        {
        }
        public MyCustomContext(DbContextOptions options) : base(options)
        {
            //Database.EnsureCreated();
        }
        protected override  void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            var typesToRegister = Assembly.GetExecutingAssembly().GetTypes()
                .Where(type => !String.IsNullOrEmpty(type.Namespace))
                .Where(type => type.BaseType != null  && type.BaseType.IsGenericType &&
                               type.BaseType.GetGenericTypeDefinition() == typeof(EntityConfigurationBase<>));
            foreach (var type in typesToRegister)
            {
                dynamic configInstance = Activator.CreateInstance(type);
                modelBuilder.ApplyConfiguration(configInstance);
            }
        }
    }
}