Changed registry plugin to re-implement only the _relation method

This way the registry plugin can be used in custom relations created with _relation

src/plugins/registry.js

@@ -55,18 +55,20 @@ module.exports = function (bookshelf) {
 
   const { Collection, Model } = bookshelf;
 
-  // Re-implement the `bookshelf.Model` relation methods to include a check for
+  // Re-implement the `bookshelf.Model` _relation method to include a check for
   // the registered model.
-  _.each([
-    'belongsTo', 'belongsToMany', 'hasMany', 'hasOne', 'morphMany', 'morphOne',
-    'through'
-  ], method => {
-    const original = Model.prototype[method];
-    Model.prototype[method] = function(Target) {
-      // The first argument is always a model, so resolve it and call the original method.
-      return original.apply(this, [resolveModel(Target)].concat(_.drop(arguments)));
-    };
-  });
+  const _relation = Model.prototype._relation;
+  Model.prototype._relation = function (method, Target) {
+    // The second argument is always a model, so resolve it and call the original method.
+    return _relation.apply(this, [method, resolveModel(Target)].concat(_.drop(arguments, 2)));
+  }
+
+  // The `through` method doesn't use `_relation` beneath, so we have to
+  // re-implement it specifically
+  const through = Model.prototype.through;
+  Model.prototype.through = function (Target) {
+    return through.apply(this, [resolveModel(Target)].concat(_.drop(arguments)));
+  }
 
   // `morphTo` takes the relation name first, and then a variadic set of models so we
   // can't include it with the rest of the relational methods.

test/integration/plugins/registry.js

@@ -6,17 +6,17 @@ module.exports = function(Bookshelf) {
 	describe('Model Registry', function() {
 
 		before(function() {
-			this.hasOne = sinon.spy(Bookshelf.Model.prototype, 'hasOne');
+			this._relation = sinon.spy(Bookshelf.Model.prototype, '_relation');
 			this.morphTo = sinon.spy(Bookshelf.Model.prototype, 'morphTo');
 		});
 
 		after(function() {
-			this.hasOne.restore();
+			this._relation.restore();
 			this.morphTo.restore();
 		});
 
 		beforeEach(function () {
-			this.hasOne.reset();
+			this._relation.reset();
 			this.morphTo.reset();
 		});
 
@@ -155,7 +155,7 @@ module.exports = function(Bookshelf) {
 
 			it('applies the resolved model to the original method', function() {
 				this.model._hasOne();
-				expect(this.hasOne).to.have.been.calledWith(this.relatedModel);
+				expect(this._relation).to.have.been.calledWith('hasOne', this.relatedModel);
 			});
 
 			it('allows for *-through relations', function() {
@@ -197,4 +197,4 @@ module.exports = function(Bookshelf) {
 		});
 
 	});
-};
+};