Entity Framework - how to implement Tags (for Articles / Pages)

Question

I'm writing a EF based website which will have many Articles (with id, author, date, title etc attributes) each of which is a member of a Category (10 possible categories each with id, title, associated icon etc)

Each article can also have several "tags". Like the question-tags that apply to SO questions.

For example Article ID 1 has:

• Title: "10 most popular baby names of 2016", Author: "Jo Bloggs", Date: 2017-02-01, etc
• CategoryID: 2 (foreign key to Category table where ID 2 is the "Year In Review" category)
• (This is the part I'm unclear about) Tags: "Lists", "Top 10s", "Parenting", "2016", "Trends", "Babies", "Names"

Article ID 2 ("50 life hacks I discovered this year")

• has its own Title, Author etc, also a FK to Category ID 2
• (This is the part I'm unclear about) Tags: "2016", "Lists", "Life Hacks", "Self improvement"

From the above there are 9 'distinct' tags of which 2016 and Lists apply to both articles and the others appear once each.

With a large number of articles there are an increasingly large number of tags.

Is this just a case of a many-to-many relationship of Article to Tag or is there some more natural/idiomatic way to represent that using EF?

The main things I want to do are:

• On an article page, show the tags that apply to that article (like the Stack Overflow tags that apply to a question when you view it).
• Show a 'tag cloud' or list of tags with the number of articles that have been tagged as that. e.g. Lists (2) , Trends (1)
• Potentially when creating an Article, be able to create a new Tag to go with it if the tag doesn't already exist (although if this is too difficult I can create the tag upfront instead).

I don't need to:

• query the articles to find articles where tag = THIS and not THAT or any similar logic
• preserve the ordering of the tags (I will sort them in the view/controller logic so it doesn't matter in what order they are stored)

What I need to know:

• How should I model the tags in the database (should there be a Tag table and a ArticleTag table (ArticleID, TagID) or something else?)
• What would I need to model using EF to represent the article--tag relationship efficiently?

My background is database so I understand about FKs and link tables etc, but am struggling on the EF side.

Note about my requirements: This is for a website I am creating for myself, so I already know the requirements. I won't have a situation where "the user" asks to be able to keep the ordering of the tags, for example.

Answer 1

You can add 2 Tables, Tag and TagRelation, Tag is responsible for saving TagNames such as #Test #AnotherTest, make sure there is no way to insert same tagName. In TagRelation you should keep the TagId (Fk of Tag table) and Guid (Fk of Article, Page and you name it). In this architecture every table needing Tag, must have a field with Guid type(uniqueidentifier in SQL data type) when you searching for ex. article you simply set inner join with TagRelation on Guid fields

public class Tag
{
    public long Id { get; set; }
    public string TagName { get; set; }
}

public class TagRelation
{
    public long Id { get; set; }
    public long TagId { get; set; }
    public Guid FkUniqueGuid { get; set; }

}

public class Article
{
    public long Id { get; set; }
    public Guid UniqueGuid { get; set; }
    //And another fields
}