fix: Don't force |null on BelongsTo relations using ->withTrashed() (#1783)

When the related model uses SoftDeletes, `isRelationNullable()` was
forcing the BelongsTo relation type to nullable even if the relation
explicitly opted into trashed parents via `->withTrashed()`. Combined
with a NOT NULL FK column and DB-level FK constraint, the relation is
effectively non-nullable.

The SoftDeletes branch is now skipped when the relation has removed
the `SoftDeletingScope` and added no constraint on the qualified
`deleted_at` column. `->onlyTrashed()` and `->withoutTrashed()` keep
their nullable annotation because they restrict the parent to a
specific soft-delete state.

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

tests/Console/ModelsCommand/SoftDeletesRelations/Models/ModelWithRelations.php

@@ -17,6 +17,21 @@ class ModelWithRelations extends Model
         return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id');
     }
 
+    public function softDeletableWithTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->withTrashed();
+    }
+
+    public function softDeletableOnlyTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->onlyTrashed();
+    }
+
+    public function softDeletableWithoutTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->withoutTrashed();
+    }
+
     public function nonSoftDeletable(): BelongsTo
     {
         return $this->belongsTo(NonSoftDeletableModel::class, 'non_soft_deletable_model_id');

tests/Console/ModelsCommand/SoftDeletesRelations/__snapshots__/Test__testSoftDeletesForceNullableDisabled__1.php

@@ -16,6 +16,9 @@ use Illuminate\Database\Eloquent\Relations\HasOne;
  * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\NonSoftDeletableModel|null $nonSoftDeletableHasOne
  * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel $softDeletable
  * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel|null $softDeletableHasOne
+ * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel $softDeletableOnlyTrashed
+ * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel $softDeletableWithTrashed
+ * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel $softDeletableWithoutTrashed
  * @method static \Illuminate\Database\Eloquent\Builder<static>|ModelWithRelations newModelQuery()
  * @method static \Illuminate\Database\Eloquent\Builder<static>|ModelWithRelations newQuery()
  * @method static \Illuminate\Database\Eloquent\Builder<static>|ModelWithRelations query()
@@ -33,6 +36,21 @@ class ModelWithRelations extends Model
         return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id');
     }
 
+    public function softDeletableWithTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->withTrashed();
+    }
+
+    public function softDeletableOnlyTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->onlyTrashed();
+    }
+
+    public function softDeletableWithoutTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->withoutTrashed();
+    }
+
     public function nonSoftDeletable(): BelongsTo
     {
         return $this->belongsTo(NonSoftDeletableModel::class, 'non_soft_deletable_model_id');

tests/Console/ModelsCommand/SoftDeletesRelations/__snapshots__/Test__test__1.php

@@ -16,6 +16,9 @@ use Illuminate\Database\Eloquent\Relations\HasOne;
  * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\NonSoftDeletableModel|null $nonSoftDeletableHasOne
  * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel|null $softDeletable
  * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel|null $softDeletableHasOne
+ * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel|null $softDeletableOnlyTrashed
+ * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel $softDeletableWithTrashed
+ * @property-read \Barryvdh\LaravelIdeHelper\Tests\Console\ModelsCommand\SoftDeletesRelations\Models\SoftDeletableModel|null $softDeletableWithoutTrashed
  * @method static \Illuminate\Database\Eloquent\Builder<static>|ModelWithRelations newModelQuery()
  * @method static \Illuminate\Database\Eloquent\Builder<static>|ModelWithRelations newQuery()
  * @method static \Illuminate\Database\Eloquent\Builder<static>|ModelWithRelations query()
@@ -33,6 +36,21 @@ class ModelWithRelations extends Model
         return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id');
     }
 
+    public function softDeletableWithTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->withTrashed();
+    }
+
+    public function softDeletableOnlyTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->onlyTrashed();
+    }
+
+    public function softDeletableWithoutTrashed(): BelongsTo
+    {
+        return $this->belongsTo(SoftDeletableModel::class, 'soft_deletable_model_id')->withoutTrashed();
+    }
+
     public function nonSoftDeletable(): BelongsTo
     {
         return $this->belongsTo(NonSoftDeletableModel::class, 'non_soft_deletable_model_id');