Anders Tornblad, web developer

I'm all about the web

Reinventing a PHP MVC framework, part 3

Let's add some spokes to the wheel

This is the third part of a series of articles about the mt-mvc PHP MVC framework. If you haven't read the first parts, here is the first one: Reinventing a PHP MVC framework, part 1

When an HTTP request is handled by ASP.NET, a factory called DefaultControllerFactory goes to work. Its CreateController method looks through the web app's controller classes using reflection, finds the right one and creates an instance. Then the infrastructure takes a look at which method to call, again using reflection, and the method gets called. The result, some ActionResult subclass, then produces the correct view.

The mechanism relies heavily on reflection which is really difficult to unit-test, because you would have to mock the entire class system and file system. So this part is not developed using TDD, but write-and-debug. I'm sorry!

PHP doesn't have precompiled assemblies that the infrastructure can search through to find the correct class. Instead we need to take a convention over configuration approach, and pick some standards to enforce. Using PHP's autoload capabilities, we can write an autoloader specifically for controllers. The "controller factory" then simply turns into a call to class_exists. The autoloader is detailed in a future article.

Target in sight

The next piece of the puzzle is what I would like to call the MVC framework itself – a class that binds request, routing and response together. The request and response are mocked, and the workflow looks a little like this:

  1. Get path of url from request handler
  2. Translate path into route information using the routing system
  3. Check the method signature of the method requested:
    • If the method requires a single piece of trivial input, and the parameter is called $id, first try the parameter value from the route information
    • If the method requires additional or non-trivial input, get post data from request handler, using prefixed or non-prefixed keys
    • Build the required input model, if any
    • Because the input model will get passed to a method, the input model is an array of arguments in correct order for passing to the method
  4. Run the method, passing the input model as arguments
  5. Execute the result using the response handler

The routing bit is already in place, albeit not complete for non-trivial production purposes. The next step is creating an input model builder, and here are the first set of tests for it:

class InputModelBuilderTests { public function ReturnsNullForMethodWithoutParameters() { $class = new \ReflectionClass(ImbtControllerDummy::class); $method = $class->getMethod('NoParametersMethod'); // No expected calls to request or route! Expect($route); Expect($request); $builder = new InputModelBuilder(); $result = $builder->buildInputModel($method, $request, $route); The($result)->ShouldEqual([]); } public function ReturnsRouteParameterForSimpleParameterMethod() { $class = new \ReflectionClass(ImbtControllerDummy::class); $method = $class->getMethod('SimpleParameterMethod'); // No expected calls to request! Expect($route)->toGet('parameter', 'abc.123'); Expect($request); $builder = new InputModelBuilder(); $result = $builder->buildInputModel($method, $request, $route); $route->checkAll(); $request->checkAll(); The($result)->ShouldEqual(['abc.123']); } public function ReturnsPostIdForSimpleParameterMethod() { $class = new \ReflectionClass(ImbtControllerDummy::class); $method = $class->getMethod('SimpleParameterMethod'); Expect($route)->toGet('parameter', null); Expect($request)->toGet('post', ['id' => 'abc.123']); $builder = new InputModelBuilder(); $result = $builder->buildInputModel($method, $request, $route); $route->checkAll(); $request->checkAll(); The($result)->ShouldEqual(['abc.123']); } public function ReturnsPostDataForTwoSimpleParametersMethod() { $class = new \ReflectionClass(ImbtControllerDummy::class); $method = $class->getMethod('TwoSimpleParametersMethod'); // No expected calls to route! Expect($route); Expect($request)->toGet('post', ['bar' => 'QWER', 'foo' => 'ASDF']); $builder = new InputModelBuilder(); $result = $builder->buildInputModel($method, $request, $route); $route->checkAll(); $request->checkAll(); The($result)->ShouldEqual(['ASDF', 'QWER']); } public function ReturnsNonprefixedPostDataForComplexParameterMethod() { $class = new \ReflectionClass(ImbtControllerDummy::class); $method = $class->getMethod('SmallInputModelMethod'); // No expected calls to route! Expect($route); Expect($request)->toGet('post', ['bar' => 'QWER', 'foo' => 'ASDF']); $builder = new InputModelBuilder(); $result = $builder->buildInputModel($method, $request, $route); $route->checkAll(); $request->checkAll(); The(count($result))->ShouldBeExactly(1); The($result[0])->ShouldBeInstanceOf(\ImbtSmallInputModel::class); The($result[0]->foo)->ShouldEqual('ASDF'); The($result[0]->bar)->ShouldEqual('QWER'); } public function ReturnsPrefixedPostDataForComplexParameterMethod() { $class = new \ReflectionClass(ImbtControllerDummy::class); $method = $class->getMethod('SmallInputModelMethod'); // No expected calls to route! Expect($route); Expect($request)->toGet('post', ['model-bar' => 'QWER', 'model-foo' => 'ASDF']); $builder = new InputModelBuilder(); $result = $builder->buildInputModel($method, $request, $route); $route->checkAll(); $request->checkAll(); The(count($result))->ShouldBeExactly(1); The($result[0])->ShouldBeInstanceOf(\ImbtSmallInputModel::class); The($result[0]->foo)->ShouldEqual('ASDF'); The($result[0]->bar)->ShouldEqual('QWER'); } } class ImbtControllerDummy { public function NoParametersMethod() { } public function SimpleParameterMethod($id) { } public function TwoSimpleParametersMethod($foo, $bar) { } public function SmallInputModelMethod(ImbtSmallInputModel $model) { } } class ImbtSmallInputModel { public $foo; public $bar; }

Making these tests succeed is not that hard, but I have to admit that we have strayed a little from the ASP.NET path now. This is intentional. I want the ease-of-use of ASP.NET, but also want to add some ideas of my own.

class InputModelBuilder { public function buildInputModel(ReflectionMethod $method, $request, $route) { $parameters = $method->getParameters(); $parameterCount = count($parameters); if ($parameterCount === 0) { return []; } $result = []; foreach ($parameters as $index => $parameter) { $typeHint = $parameter->getClass(); $name = $parameter->getName(); // Trivial single-value input model named $id: if ($name == 'id' && !isset($typeHint) && $parameterCount === 1) { // This is the only time the $route->parameter is used! $value = @$route->parameter; if (isset($value)) { return[$value]; } } if (!isset($postData)) $postData = $request->post; if (!isset($typeHint)) { // Trivial single value from post if (isset($postData[$name])) { $result[] = $postData[$name]; } } else { // Type-hinted value $result[] = $this->buildTypeHintedObject($name, $typeHint, $postData); } } return $result; } private function buildTypeHintedObject($optionalPrefix, ReflectionClass $typeHint, array $postData) { $className = $typeHint->getName(); $result = new $className; $properties = $typeHint->getProperties(); foreach ($properties as $property) { $name = $property->getName(); $prefixedName = "$optionalPrefix-$name"; if (isset($postData[$prefixedName])) { $property->setValue($result, $postData[$prefixedName]); } else if (isset($postData[$name])) { $property->setValue($result, $postData[$name]); } } return $result; } }

The bits and pieces are starting to fall into place, but they all need to be put together. Come back here in a while for more on that.

Reinventing a PHP MVC framework, part 1
Reinventing a PHP MVC framework, part 2
Reinventing a PHP MVC framework, part 3 (this part)
Reinventing a PHP MVC framework, part 4

You'll find the code from this article in the related release on GitHub. The latest version is always available in the GitHub repository.

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