Laravel one-to-one relationship fails - php

Question

I created two migrations, because I wanted to create a one-to-one relationship between Trend and TrendExplanation.
Schema::create('trend_explanations', function (Blueprint $table) {
$table->increments('id');
$table->text('demographical')->nullable();
$table->text('economical')->nullable();
$table->text('social')->nullable();
$table->text('technological')->nullable();
$table->text('ecological')->nullable();
$table->text('political')->nullable();
$table->timestamps();
});
This is the migration for the Trend model:
Schema::create('trends', function (Blueprint $table) {
$table->increments('id');
$table->integer('explanation_id')->unsigned();
$table->foreign('explanation_id')->references('id')->on('trend_explanations');
$table->string('name');
$table->date('date');
$table->text('description');
$table->timestamps();
});
So in the models I did the following additions:
class Trend extends Model
{
public function explanation()
{
return $this->hasOne(TrendExplanation::class);
}
}
And of course I created a seeder to test it out:
$trend = new Trend();
$trend->name = "Something";
$trend->description = "Description";
$explanation = new TrendExplanation();
// ...
$trend->explanation()->save($explanation);
$trend->save();
And when I run it, I receive the error: [Illuminate\Database\QueryException] SQLSTATE[42S22]: Column not found: 1054 Unknown column 'trend_id' in 'field list'.
How does this happen? I don't understand what I did wrong here.

Answer 1

You can specify the foreign and local keys when specifying the relationship. It usually goes
$this->hasOne(Class, foreign, local);
So your definition would be:
return $this->hasOne(TrendExplanation::class, 'id', 'explanation_id');