首先使用EF代码创建数据库和表

Question

I am going to create a database and tables with EF Code First.

Each Post belongs to a single Category and it can be labelled with many Tags. Between Post and Category the relationship is many-to-one and between Post and Tag the relationship is many-to-many.

Below is my code:

public class BlogContext : DbContext
{
    public DbSet<Post> Posts { get; set; }
    public DbSet<PostTagMap> PostTags { get; set; }
    public DbSet<Category> Categorys { get; set; }
    public DbSet<Tag> PostTags { get; set; }
}
public class Post
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string ShortDescription { get; set; }
    public string Meta { get; set; }
    public string UrlSlug { get; set; }
    public bool Published { get; set; }
    public DateTime PostedOn { get; set; }
    public DateTime? Modified { get; set; }
    public Category Category { get; set; }
    public IList<Tag> Tags { get; set; }
}
public class PostTagMap
{

}
public class Category
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string UrlSlug { get; set; }
    public string Description { get; set; }
    public IList<Post> Posts { get; set; }
}
public class Tag
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string UrlSlug { get; set; }
    public string Description { get; set; }
    public IList<Post> Posts { get; set; }
}

Here are the EF new guy's questions:

1. Do I generate code for PostTagMap ?
2. How to apply relationship between tables to my code?
3. I always saw that people add DataAnnotation at this moment? Because many online samples created DB without this step, I am confused.

Answer 1

Your data model looks fine. I would use that. For your questions:

Do I generate code for PostTagMap? what kind of code you want to generate? If you mean, do u define any code for it. you dont really need to since you already have a relationship defined between post and tag. But you can if you think it will be easier for you to query.

How to apply relationship between tables to my code? The relationship is already there. Such as Category has many posts and a post belongs to a category.

I always saw that people add DataAnnotation at this moment? Because many online samples created DB without this step, I am confused. Annotaions are used as cross cutting concerns such as validation, data type, data length and so forth.