Making progress on fixing relations

src/Jenssegers/Mongodb/Relations/BelongsTo.php

 <?php namespace Jenssegers\Mongodb\Relations;
 
+use Illuminate\Database\Eloquent\Builder;
+
 class BelongsTo extends \Illuminate\Database\Eloquent\Relations\BelongsTo
 {
     /**
@@ -28,6 +30,14 @@ class BelongsTo extends \Illuminate\Database\Eloquent\Relations\BelongsTo
         $this->query->whereIn($key, $this->getEagerModelKeys($models));
     }
 
+    /**
+     * @inheritdoc
+     */
+    public function getRelationExistenceQuery(Builder $query, Builder $parentQuery, $columns = ['*'])
+    {
+        return $query;
+    }
+
     /**
      * Get the owner key with backwards compatible support.
      */

src/Jenssegers/Mongodb/Relations/BelongsToMany.php

 <?php namespace Jenssegers\Mongodb\Relations;
 
+use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsToMany as EloquentBelongsToMany;
 
 class BelongsToMany extends EloquentBelongsToMany
 {
+    /**
+     * Get the key for comparing against the parent key in "has" query.
+     *
+     * @return string
+     */
+    public function getHasCompareKey()
+    {
+        return $this->getForeignKey();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getRelationExistenceQuery(Builder $query, Builder $parentQuery, $columns = ['*'])
+    {
+        return $query;
+    }
+
     /**
      * @inheritdoc
      */
@@ -25,6 +44,14 @@ class BelongsToMany extends EloquentBelongsToMany
         return $columns;
     }
 
+    /**
+     * @inheritdoc
+     */
+    protected function shouldSelect(array $columns = ['*'])
+    {
+        return $columns;
+    }
+
     /**
      * @inheritdoc
      */
@@ -260,6 +287,14 @@ class BelongsToMany extends EloquentBelongsToMany
         return $this->foreignKey;
     }
 
+    /**
+     * @inheritdoc
+     */
+    public function getQualifiedForeignKeyName()
+    {
+        return $this->foreignKey;
+    }
+
     /**
      * Format the sync list so that it is keyed by ID. (Legacy Support)
      * The original function has been renamed to formatRecordsList since Laravel 5.3

src/Jenssegers/Mongodb/Relations/HasMany.php

@@ -5,6 +5,26 @@ use Illuminate\Database\Eloquent\Relations\HasMany as EloquentHasMany;
 
 class HasMany extends EloquentHasMany
 {
+    /**
+     * Get the key for comparing against the parent key in "has" query.
+     *
+     * @return string
+     */
+    public function getHasCompareKey()
+    {
+        return $this->getForeignKeyName();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getRelationExistenceQuery(Builder $query, Builder $parentQuery, $columns = ['*'])
+    {
+        $foreignKey = $this->getHasCompareKey();
+
+        return $query->select($foreignKey)->where($foreignKey, 'exists', true);
+    }
+
     /**
      * Add the constraints for a relationship count query.
      *
@@ -16,7 +36,7 @@ class HasMany extends EloquentHasMany
     {
         $foreignKey = $this->getHasCompareKey();
 
-        return $query->select($this->getHasCompareKey())->where($this->getHasCompareKey(), 'exists', true);
+        return $query->select($foreignKey)->where($foreignKey, 'exists', true);
     }
 
     /**
@@ -35,14 +55,4 @@ class HasMany extends EloquentHasMany
 
         return $query->where($this->getHasCompareKey(), 'exists', true);
     }
-
-    /**
-     * Get the plain foreign key.
-     *
-     * @return string
-     */
-    public function getPlainForeignKey()
-    {
-        return $this->getForeignKey();
-    }
 }

src/Jenssegers/Mongodb/Relations/HasOne.php

@@ -5,6 +5,36 @@ use Illuminate\Database\Eloquent\Relations\HasOne as EloquentHasOne;
 
 class HasOne extends EloquentHasOne
 {
+    /**
+     * Get the key for comparing against the parent key in "has" query.
+     *
+     * @return string
+     */
+    public function getForeignKeyName()
+    {
+        return $this->foreignKey;
+    }
+
+    /**
+     * Get the key for comparing against the parent key in "has" query.
+     *
+     * @return string
+     */
+    public function getHasCompareKey()
+    {
+        return $this->getForeignKeyName();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getRelationExistenceQuery(Builder $query, Builder $parentQuery, $columns = ['*'])
+    {
+        $foreignKey = $this->getForeignKeyName();
+
+        return $query->select($foreignKey)->where($foreignKey, 'exists', true);
+    }
+
     /**
      * Add the constraints for a relationship count query.
      *
@@ -14,9 +44,9 @@ class HasOne extends EloquentHasOne
      */
     public function getRelationCountQuery(Builder $query, Builder $parent)
     {
-        $foreignKey = $this->getHasCompareKey();
+        $foreignKey = $this->getForeignKeyName();
 
-        return $query->select($this->getHasCompareKey())->where($this->getHasCompareKey(), 'exists', true);
+        return $query->select($foreignKey)->where($foreignKey, 'exists', true);
     }
 
     /**
@@ -33,16 +63,6 @@ class HasOne extends EloquentHasOne
 
         $key = $this->wrap($this->getQualifiedParentKeyName());
 
-        return $query->where($this->getHasCompareKey(), 'exists', true);
-    }
-
-    /**
-     * Get the plain foreign key.
-     *
-     * @return string
-     */
-    public function getPlainForeignKey()
-    {
-        return $this->getForeignKey();
+        return $query->where($this->getForeignKeyName(), 'exists', true);
     }
 }

src/Jenssegers/Mongodb/Relations/MorphTo.php

@@ -28,7 +28,7 @@ class MorphTo extends EloquentMorphTo
 
         $query = $instance->newQuery();
 
-        return $query->whereIn($key, $this->gatherKeysByType($type)->all())->get();
+        return $query->whereIn($key, $this->gatherKeysByType($type))->get();
     }
 
     /**