Laravel帖子和标签：有很多直通关系吗？

Question

I'm making a Laravel application.

I have a posts table that stores "blog posts". I also have a tags table to store tags (eg: "Cooking" for cooking posts, "Books" for book posts). Each post can have many tags. I setup my database as such

Posts

• id
• text
• title

Tags

• id
• name

PostTags

• id
• tag_id
• post_id

Is this a "HasManyThrough" relationship in Laravel/Eloquent? I tried setting up my model using

public function tags()
{
   return $this->hasManyThrough('App\Tag', 'App\PostTag')
}

However, this isn't working - throwing exceptions telling me the column names don't exist.

Answer 1

This was actually a "belongsToMany" relationship - what I was missing was the fact you can specify a pivot table using an argument when declaring the relationship like so:

public function tags()
{
   return $this->belongsToMany('App\Tag', 'post_tags')
}

Answer 2

It is not a has-many-through relationship.

A post can belong to many tags (eg: post "Foobar" can belong to "foo" and "bar" tags). A tag can belong to many posts (eg: tag "foo" can belong to posts "Foobar" and "Another post").

So, in a Post class you would have

public function tags()
{
    return $this->belongsToMany(Tag::class);
}

and in the Tag class you would define the inverse

public function posts()
{
    return $this->belongsToMany(Post::class);
}

Read more in the official docs .