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How can I make "nullable" one-to-one relationship in the same model, where I don't store alot of null values inside my table? Let me explain the problem:
I have a User model that may be linked with another User model.
$table->uuid('id')->primary();
$table->string('email')->unique();
$table->string('password');
....
I know that I can add a new column to User's table named user_id which references itself, so I can make a one-to-one relationship. But doing this way, will make alot of users with a "null" value within user_id column.
Knowing this, I tried to make a separated table named user_parents in which I store the User's ID and the Related User's ID.
$table->uuid('id')->primary();
$table->foreignUuid('user_id')->constrained();
$table->foreingUuid('parent_id')->constrained('users');
...
Then I created a HasOne relationship within User's, and a User/Parent relation within UserParents
public function parent(): HasOne
{
return $this->hasOne(UserParent::class);
}
...
public function parent(): BelongsTo
{
return $this->belongsTo(UserParent::class, 'parent_id', 'id');
}
public function user(): BelongsTo
{
return $this->belongsTo(User::class);
}
...
But I to access a User's parent data, I aways have to go thorugh two relations, and this doesn't feel right to me. Is this the intended way, or is there a better way to do it?
echo $user->parent->parent->email;
I haven't experimented with Nulll Object Pattern in one to one relationships (or with one to one relationships at all).
But I think you could get away with setting the withDefault() method on your one to one relationship using the user_id value approach.
Here are the docs: https://laravel.com/docs/9.x/eloquent-relationships#default-models
@undeportedmexican I don't think withDefault() solves my problem because it returns a value when a model isn't found (null). But my problem is in how to access the relationship properly.
Anyway, if you have time, can you write a simple example of your solution?
@Arthur Henrique
I'm thinking something like this:
User Model
public function parent(){
return $this->hasOne(User::class, 'user_id')->withDefault([
'name' => 'No parent selected',
]);
}
So that in the event the user_id is null, you will get an object with the name property set to No parent selected
Again, I haven't experimented with this, but I think it could work on your case.
@undeportedmexican Thanks for the time. Actually, my problem isn't this one.
I can't do this because I don't have user_id inside User's model. I have within UserParent's model. I didin't put inside the User's model because I don't want to have numerous empty "user_id" value within the table.
Precisely, my question is how to make a relationship that access UserParents.parent_id and returns a user.
With the example I made in the main post, I have to access the data this way:
$user->parent->parent->email;
// We have a user
// Access the User parent relation, to get a UserParent
// Access the UserParent parent relation, to get a User
// Access the wanted data email
I wish that I could retrieve data like this
$user->parent->email;
// We have a user
// Access the User parent relation, to get a User, based on UserParent parent_id
// Access the wanted data email
I would move that relation into a pivot like table to store the relation just like you tried. I don't know what the relation is that you want but if it's parent child then it's a many to .many you should use.
A parent can have more than one child and a child can have more than one parent,.
Take a look at this post, it might give you some tips
Did you find the solution to this? I'm have same problem. I have to do a recursive query to find the parent record. Like model->parent->parent->attribute
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