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I'm trying to get an attribute from a related model to use in a date calculation but I get the error 'Attempt to read property "duration" on null'. Is what I'm trying to do even possible inside a model?
public function scopeUpcoming($query)
{
return $query->where('date', '>', now()->subMinutes($this->calculateDuration()));
}
public function calculateDuration()
{
return $this->booking->duration;
}
public function booking()
{
return $this->belongsTo(Booking::class);
}
Running the query through Tinker gives me the expected value so I don't know where I'm going wrong. Any help would be greatly appreciated.
$event->booking->duration => 30
@pom the problem is that $this->booking returns null (no associated booking). make it optional
public function calculateDuration()
{
return optional($this->booking)->duration;
}
or use null safe operator (for php >8.0)
public function calculateDuration()
{
return $this->booking?->duration;
}
@SilenceBringer that's the thing it shouldn't be null, booking_id is a required field. It's got me stumped.
@pom check it manually in the database. Maybe associated booking was removed.
Or maybe you have another booking accessor?
@SilenceBringer I've tried emptying the database and adding one booking and I've tried renaming the relationship something completely random and I still get the same results. Arrgh 😭
@pom the problem is - as I told you - model do not have associated booking. Do you add booking via relationship? Are you sure you have correct relationship declaration? (does you follow conventions in db column names?)
@SilenceBringer I've updated the controllers store method to use the relationship and still get the same result. I'm using the database naming conventions. I can open the database with TablePlus and see the relationship and click through to the related tuple.
Schema::create('bookings', function (Blueprint $table) {
$table->id();
$table->string('name');
$table->unsignedInteger('duration');
$table->unsignedInteger('fee');
$table->timestamps();
});
Schema::create('events', function (Blueprint $table) {
$table->id();
$table->uuid()->unique();
$table->foreignId('booking_id')->constrained();
$table->dateTime('date');
$table->foreignId('venue_id')->nullable()->constrained();
$table->dateTime('published')->nullable();
$table->timestamps();
});
My current query:
Event::query()->upcoming()->get();
@pom That all looks correct. Can you post the full model for both as well so we can recreate it. And show the 2 test records you have in your database
Do you have some other custom accessors or perhaps global scopes?
Okay, I'm not convinced that what I'm trying to do will even work. I've just created a blank Laravel project with the customary Post and Comment models.
Post Table
public function up()
{
Schema::create('posts', function (Blueprint $table) {
$table->id();
$table->string('title');
$table->text('body');
$table->unsignedInteger('duration');
$table->timestamps();
});
}
Comment Table
public function up()
{
Schema::create('comments', function (Blueprint $table) {
$table->id();
$table->foreignId('post_id')->constrained();
$table->text('body');
$table->timestamps();
});
}
Post Model
class Post extends Model
{
use HasFactory;
public function comments()
{
return $this->hasMany(Comment::class);
}
}
Comment Model
class Comment extends Model
{
use HasFactory;
public function post()
{
return $this->belongsTo(Post::class);
}
public function scopeCalculate($query)
{
return $query->where('id', '=', $this->calculateDuration());
}
private function calculateDuration()
{
//return 1;
return $this->post->duration;
}
}
Database Seeder
class DatabaseSeeder extends Seeder
{
public function run()
{
$post = Post::create([
'title' => 'Post Title',
'body' => 'Body of the post. Some random text.',
'duration' => 1,
]);
$post->comments()->create([
'body' => 'A comment on the post.',
]);
}
}
Web Route
Route::get('/', function () {
return \App\Models\Comment::query()->calculate()->get();
});
I get the same error 'Attempt to read property "duration" on null'.
@pom Ah sorry I totally missed that you called it in the scope.. You cannot call a relationship before it exists. It does not exist before the query is run. So that isnt possible. Instead you need to do a subquery and do the subtraction of minutes in sql, not php
@Sinnbeck you didn't miss it. It was not mentioned in original post
Thanks for your help @sinnbeck and @SilenceBringer that makes complete sense.
The local scope was in the original post.
public function scopeUpcoming($query)
{
return $query->where('date', '>', now()->subMinutes($this->calculateDuration()));
}
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