The key to creating a one-to-many relationship in Laravel is to correctly set up the model and database structure. First, define the database table structure, the users table contains id, and the posts table contains the user_id foreign key pointing to users.id; secondly, use hasMany to define one-to-many relationships in the User model, and use belongsTo to define the reverse relationship in the Post model; finally query the data through $user->posts or $post->user, and use with() to preload with optimization performance; at the same time, pay attention to the consistent foreign key field types, correct naming and correct model namespace references to ensure that the relationship works normally.
Creating a one-to-many relationship in Laravel is not complicated. As long as you understand the correlation logic between models, it is very direct to implement it. The key is to correctly set up how the two models are connected and ensure that the database structure supports this relationship.

Define the database structure
Before you start writing a model, you must prepare the database table structure. For example, we have two models: User
and Post
, and a user can have multiple articles.
You need two tables:

-
users
table (main table): contains at least one primary keyid
-
posts
table (from table): There needs to be a foreign key field, such asuser_id
, which is used to point tousers.id
For example:
Schema::create('posts', function (Blueprint $table) { $table->id(); $table->unsignedBigInteger('user_id'); $table->string('title'); $table->text('content'); $table->timestamps(); $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade'); });
This step is the basis. If there is no correct foreign key constraint, there may be problems with the subsequent relationship query.

Define relationships in the model
Next, define a “one-to-many” relationship in the model.
Definition in User model to get all Posts
class User extends Model { use HasFactory; public function posts() { return $this->hasMany(Post::class); } }
Define the User to which it belongs in the Post model
Although it is not necessary, for the convenience of two-way query, you can also add:
class Post extends Model { use HasFactory; public function user() { return $this->belongsTo(User::class); } }
By default, Laravel will automatically use user_id
as a foreign key. If you use a different name, such as author_id
, you need to specify it manually:
return $this->hasMany(Post::class, 'author_id');
Query and use relationship data
After defining the relationship, you can easily query it.
For example, obtain all articles of a user:
$user = User::find(1); $posts = $user->posts;
Or query with conditional:
$posts = $user->posts()->where('published', true)->get();
In turn, check the author information from an article:
$post = Post::find(1); $user = $post->user;
You can also use with()
preload to optimize performance to avoid N1 query problems:
$users = User::with('posts')->get();
Notes and FAQs
- Ensure that the types of foreign key fields in the database are consistent, such as
unsignedBigInteger
- If the relationship cannot be found, check whether the model refers to the correct namespace
- Use
dd($user->posts)
to view the data structure returned by the relationship and help debugging - Do not spell the foreign key fields incorrectly, for example, if you write it as
user_idd
, there will be problems.
Basically that's it. There seem to be many steps, but each step is not complicated. As long as you pay attention to the consistency of the model and the database, you can successfully establish a one-to-many relationship.
The above is the detailed content of How to create a one-to-many relationship in Laravel?. For more information, please follow other related articles on the PHP Chinese website!

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