How to create a Pivot table in Laravel

问题

I have a sponsorship app I'm creating and trying to get a pivot table working between my users and kids, but when I have a user sponsor a kid, the pivot table kid_user is not populated with the kid_id or the user_id. Not sure what I'm missing.

A Kid can have as many users (sponsors) as their slots allow them.
Users can sponsor a kid, multiple kids or the same kid multiple times if needed.

Here is my kid_user pivot table:

public function up()
{
    Schema::create('kid_user', function (Blueprint $table) {
        $table->integer('kid_id')->unsigned()->index();
        $table->foreign('kid_id')->references('id')->on('kids')->onDelete('cascade');
        $table->integer('user_id')->unsigned()->index();
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
        $table->primary(['kid_id', 'user_id']);
    });
}

Then on the User model: The user can have many kids...

public function kid()
{
    return $this->hasMany(Kid::class);
}

Then on the Kid model: The kids can have many users...

  public function user() {
      //return $this->belongsTo(User::class); (Tried this..)
        return $this->hasMany(User::class);
  }

Here are the tables I'm using. (Only relevant info is included in the tables)

+---------------------+
| Tables_in_Database  |
+---------------------+
| kid_user            |
| kids                |
| users               |
+---------------------+

+-----------------------------+
|        users table          |
+----+------------+-----------+
| id | first_name | last_name |
+----+------------+-----------+
|  1 | John       | Smith     |
|  2 | Jane       | Doe       |
+----+------------+-----------+

+-----------------------------+
|        kids table           |
+----+------------+-----------+-------+
| id | first_name | last_name | slots |
+----+------------+-----------+-------+
|  1 | Bobby      | Little    |   3   | -> Can be sponsored 3 times
+----+------------+-----------+-------+

+--------------------+
|   kid_user table   | THE BELOW RESULTS ARE WHAT I'M LOOKING FOR.
+--------------------+
| *kid_id | *user_id | * = Primary Key
+---------+----------+
|    1    |     1    | -> Sponsored 1st Slot
+---------+----------+
|    1    |     2    | -> Sponsored 2nd Slot
+---------+----------+
|    1    |     1    | -> Sponsored 3rd Slot
+---------+----------+

So when a User sponsors a Kid. I would like the kid_id & user_id to be entered into the kid_user pivot table. Any help would be appreciated.

回答1:

First of all you might wanna rename the functions in your models in plural as it does not have one but many from the relationship.

So in your user model add this:

public function kids()
{
    return $this->belongsToMany(Kid::class);
}

And in your Kid model:

public function users()
{
     return $this->belongsToMany(User::class);
}

Then in order to save to the pivot table since your table naming is correct, just doing:

$user->kids()->attach($kid);

Will save it properly in the pivot table. Making sure first that you have existing User and Kid for the variables. More details here

来源：https://stackoverflow.com/questions/54153547/how-to-create-a-pivot-table-in-laravel

标签

php

mysql

laravel

laravel-5.5