Post.cs | Stack Overflow | How do I use OnModelCreating with ApplicationDbContext?

gistfile1.txt

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;
using System.Linq;
using System.Web;

namespace BlogEngine.Models
{
    public class Post : IEntity
    {
        [Key]
        public int Id { get; set; }
        [Required]
        //[StringLength(50, MinimumLength = 5, ErrorMessage = "Title must be between 5 and 50 characters long")]
        public string Title { get; set; }

        public string URL { get; set; }

        [Required]
        //[StringLength(250, MinimumLength = 50, ErrorMessage = "IntroText must be between 50 and 250 characters long")]
        public string IntroText { get; set; }
        [Required]
        //[StringLength(9999, MinimumLength = 50, ErrorMessage = "Enter something long enough to be worth clicking on please.")]
        public string Body { get; set; }

        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
        [Column(TypeName = "DateTime")]
        public DateTime Created { get; set; }

        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
        [Column(TypeName = "DateTime")]
        public DateTime? Modified { get; set; }
        [Required]
        //[StringLength(50, MinimumLength = 5, ErrorMessage = "Author's name must be between 5 and 50 characters long")]
        public string Author { get; set; }
        public List<Comment> Comments { get; set; }

        
        public int? Tags_Id { get; set; }

        [ForeignKey("Tags_Id")]
        public virtual List<Tag> Tags { get; set; }

    }
}