I have always struggled with how packages are versioned and published to the npm registry.
My main concern is that you probably want to also add a git tag to your source code when you are releasing a new version, but npm packages have their own versioning system, and include a &quot;version&quot; field in the package.json
Because of this, most of the workflows I have seen, usually involve:
<ol>
<li>Running <code>npm version ...</code>. This will update the &quot;version&quot; field in the package.json file.</li>
<li>Publishing the package to the npm registry, using the version set in previous step.</li>
<li>Committing to git, so that we track the change in package.json file.</li>
<li>Adding a git tag.</li>
<li>Pushing to git remote to track new commit and new tag.</li>
</ol>
<blockquote>
Steps 3 and 4 are frequently done automatically as part of <code>npm version</code>.
</blockquote>
For me this flow has two main problems:
<ul>
<li>
My personal preference is that everything is driven by git tags, making them the single source of truth.
This would allow to just have one manual step -&gt; <code>git tag -a v1.0.0 -m &quot;...&quot; &amp;&amp; git push origin --tags</code>. Then, this would trigger a number of potential automations, including publishing to the npm registry, but also others like creating a release with the appropriate release notes, building release artifacts, etc.
</li>
<li>
The &quot;version&quot; field in the package.json file can very easily become outdated, if you git-tag by mistake before publishing the package, or if pushing the changes fails after <code>npm version ...</code> has been run.
I&#x27;ve seen this happening more often than it seems.
</li>
</ul>
Because of this, my current take when publishing npm packages for my personal projects is:
<ol>
<li>
Get rid of the &quot;version&quot; field from the package.json file. It&#x27;s misleading in source code, as it can very easily be out of date.
The only case where it&#x27;s useful is when the package has been installed and is inside node_modules, as other packages will assume this field to exist and have the right value on it.
In this case it&#x27;s always going to be correct due to the<code>npm version ...</code> + <code>npm publish</code> tandem (see next point).
</li>
<li>
Creating the git tag is the only &quot;manual step&quot;. This triggers an automation running <code>npm version ${GIT_TAG} --git-tag-version=false &amp;&amp; npm publish</code> (this is simplified. You probably also need to build your project and other potential extra steps).
The version to publish is inferred from the git tag (<code>${GIT_TAG}</code> is just a placeholder), and only at this stage we will set the &quot;version&quot; inside package.json, just before the package is published.
</li>
<li>
Other automations that need to happen during releases, can be also triggered now, like publishing release notes, building artifacts, etc.
</li>
</ol>
<blockquote>
As an example, you can see <a target="_blank" rel="noopener noreferrer" href="https://github.com/shlinkio/github-actions/blob/24de7a2b89a9eb11b0acfd184de7187698b051b6/.github/workflows/js-lib-publish.yml">this GitHub actions workflow</a>, which follows this approach.
</blockquote>

I have always struggled with how packages are versioned and published to the npm registry. My main concern is that you probably want to also add a git tag to your source code when you are releasing a new version, but npm packages have their own versioning system, and include a "version" field in…

My current take when publishing packages to the npm registry

A couple of weeks ago I migrated a React project using redux to <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/">Redux Toolkit</a>.
Redux has always been my preferred state management tool for React (which doesn&#x27;t mean I &quot;love&quot; it), but one of its main problems is the amount of boilerplate code it requires.
Because of that I had a couple of helper functions, but there was still some things not properly handled, like proper type inference on reducers and actions (I use TypeScript).
A bit by accident (I think it was on Twitter), I found out about Redux Toolkit (RTK from now on), an official library from the redux team, which provides some opinionated helpers to reduce the amount of boilerplate, and I decided to give it a chance.
These are my impressions.
<h3>TL;DR</h3>
I first started to use it in a proof of concept, and I quickly loved it.
RTK does not &quot;replace&quot; any of the redux principles, so you can progressively adopt it, by replacing small bits of code. My plan was to use it just for some reducers, but I liked it so much that I ended up migrating the whole project in a series of consecutive pull requests.
<h3>A bit of context</h3>
Before the migration, I used to follow the <a target="_blank" rel="noopener noreferrer" href="https://github.com/erikras/ducks-modular-redux">ducks modular pattern</a>, which promotes putting all your action types, action creators and the reducer handling those actions on the same module.
This fits pretty well with RTK, as in most of the cases you will use <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createSlice">slices</a>, and end up exporting the reducer and action creators returned by it, from the same module.
If you use <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createAsyncThunk">async thunks</a>, they usually need to be used by that same slice, so it&#x27;s not a bad idea to export them also from there.
<h3>Why I love it</h3>
There are a couple of reasons for which I loved RTK right away. The main one is that they make an impressive work on making type inference in TypeScript work properly.
<ul>
<li>Slices detect the type of the initial state in order to know what is expected to be passed as <code>state</code> to reducers.</li>
<li>You can infer the type of your store from what is generated by <code>configureStore</code> or <code>combineReducers</code> functions, allowing you to also properly type the <code>dispatch</code> function.</li>
<li>Action creators are generated with the proper param types based on the reducers provided to <code>createSlice</code> or the callback provided to <code>createAsyncThunk</code>.</li>
<li><code>createSlice</code> can consume all the action creators generated by <code>createAsyncThunk</code>, and infer the proper payload for each one of them.</li>
</ul>
Thanks to this, the code is super predictable and potential bugs can be caught sooner.
<blockquote>
More details on how to use RTK with typescript https://redux-toolkit.js.org/usage/usage-with-typescript
</blockquote>
But this is not the only benefit. Other reasons that make it very nice to work with are:
<ul>
<li>It keeps the same concepts from Redux, but removing the boilerplate or your own helper functions if you have them (yes, I didn&#x27;t want to keep all those <code>switch</code> statements everywhere).</li>
<li>It is mostly transparent for the components dispatching the actions or consuming the state.</li>
<li>All the tests covering your reducers/actions/components should keep passing, as the outcome from RTK is the same as if you built everything manually.</li>
<li>It introduces a couple of extra helpers, like <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/rtk-query/overview">RTK query</a> or the <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createListenerMiddleware">listener middleware</a>, which is very useful to dispatch actions as a result of other actions being dispatched.</li>
</ul>
<h3>Challenges I found</h3>
Of course, adopting a new tool always comes with some challenges.
The main &quot;problem&quot; I found is that RTK is a bit opinionated, but that&#x27;s precisely how they manage to reduce boilerplate code, and it&#x27;s also &quot;advertised&quot; in their website, so not a big surprise.
I usually prefer to be in control of everything (configuration over convention), but that&#x27;s just a personal preference, and sometimes it&#x27;s ok to accept a bit of magic for the sake of simplicity.
This caused the next challenges for my particular case:
<ul>
<li>
RTK assumes your project follows a strict <a target="_blank" rel="noopener noreferrer" href="https://redux.js.org/tutorials/fundamentals/part-7-standard-patterns#flux-standard-actions">Flux pattern</a>, meaning your actions always have the properties <code>type</code>, <code>payload</code> and optionally <code>meta</code> and <code>error</code>.
I was not following this pattern (my actions had the payload &quot;mixed&quot; on the first object level), so I had to adapt all my actions first, fix the tests, then migrate the reducer to RTK and make sure the tests kept passing.
<div></div>
</li>
<li>
Immutability is no longer promoted in reducers. Instead, the library requires <a target="_blank" rel="noopener noreferrer" href="https://immerjs.github.io/immer/">immer</a> internally, and using proxies they automatically ensure immutability, even if you &quot;mutate&quot; the state.
This feels a bit counterintuitive at first, because redux always promoted an immutable approach, and the use of immer is not obvious.
However, they have <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/usage/immer-reducers#why-immer-is-built-in">good reasons</a> to do it, and if your reducers return a state object, you can still use the immutable approach. It&#x27;s up to you.
<div></div>
</li>
<li>
Action creators resulting of <code>createAsyncThunk</code> can only have one argument.
This is because the async thunk callback receives a second argument containing the <code>dispatch</code> and <code>getState</code> functions, as well as a couple of other goodies, enforcing this convention to avoid human errors.
<div></div>
</li>
<li>
You cannot dispatch other actions after the callback passed to <code>createAsyncThunk</code>, because it has to return the payload and RTK dispatches the action for you.
However, this is probably something you usually should not be doing, and in my case, I resolved it with the <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createListenerMiddleware">listener middleware</a>, listening for the second action in order to dispatch the second one.
</li>
</ul>
<h3>Conclusion</h3>
My conclusion is that RTK is definitely worth it if you use redux.
It makes code simpler, more predictable and better typed. However, it still requires knowing how redux works internally and what are its patterns, in order to understand why the library exposes the helpers it exposes and why.
For existing redux projects, you can migrate progressively, addressing the challenges bit by bit and not all at once, which simplifies its adoption.
For new projects in which you want to use redux, I would recommend starting right away with RTK.

A couple of weeks ago I migrated a React project using redux to Redux Toolkit. Redux has always been my preferred state management tool for React (which doesn't mean I "love" it), but one of its main problems is the amount of boilerplate code it requires.

Because of that I had a couple of helper…

My experience migrating to Redux Toolkit (RTK)

In 2019, GitHub published their own solution to run automated workflows called GitHub Actions, which allowed those hosting their code in GitHub, to be able to define and run their CI/CD pipelines in the same platform. When it was released, one of the main pain points to use it was that defining…

How to reduce duplication in your GitHub Actions workflows

Recently ReactJS v18 was released. I started to look into its improvements, and checked which of my projects could benefit from them.
The main react-based project I maintain at the moment of writing this article is <a target="_blank" rel="noopener noreferrer" href="https://github.com/shlinkio/shlink-web-client">shlink-web-client</a>, so I naturally created a new branch and started the process.
The update was quite smooth, as most of the other dependencies I was using from the react ecosystem were already updated to support v18. All but one, <a target="_blank" rel="noopener noreferrer" href="https://enzymejs.github.io/enzyme/">enzyme</a>, the testing framework I was using to unit-test react components.
To be precise, I was able to continue running my tests, but some of them (those using <code>mount</code> instead of <code>shallow</code>) were still rendering components with the &quot;old&quot; React v17 approach, causing them to behave as in that version and a warning being printed in the console.
<h3>First fix attempt</h3>
The way enzyme integrates with the react version you are using is through an adapter library. The last official one supports only React v16, but someone released an <a target="_blank" rel="noopener noreferrer" href="https://github.com/wojtekmaj/enzyme-adapter-react-17">unofficial adapter for v17</a> which, with close to 650k weekly downloads, quickly became the way to go.
I checked if there was one for React 18, but sadly there wasn&#x27;t.
Also, the author of the adapter for v17 posted an article indicating <a target="_blank" rel="noopener noreferrer" href="https://dev.to/wojtekmaj/enzyme-is-dead-now-what-ekl">enzyme is dead</a>, he was not going to release one for v18, and publishing one for v17 was a mistake.
With those facts in mind, I started to face what was probably going to be the moment to migrate to <a target="_blank" rel="noopener noreferrer" href="https://testing-library.com/docs/react-testing-library/intro">react testing library</a>.
<h3>Migration strategy</h3>
I decided to follow a migration strategy similar to the one suggested in the article above, but with a couple of modifications:
<ul>
<li>I update to React 18 anyway, as tests still pass.</li>
<li>Migrate right away all tests using <code>mount</code>, as those are the ones behaving differently.</li>
<li>New tests should be written directly with react testing library (RTL from now on).</li>
<li>When an existing test needs to be changed, consider migrating it to RTL, and do it if there&#x27;s time.</li>
<li>Introduce some PR from time to time just migrating a handful of tests.</li>
<li>Once everything is migrated, get rid of everything related with enzyme.</li>
</ul>
<h3>First contact and impressions</h3>
I was a bit sceptical with RTL, as it was focused more on integration tests, instead of unit tests, which meant I had to completely change the mindset to write tests.
It also didn&#x27;t support shallow rendering, meaning that you will end up sometimes rendering a bigger component tree when testing container-like components, potentially causing side effects that could affect your test.
On the other hand there&#x27;s more and more people stating that <a target="_blank" rel="noopener noreferrer" href="https://kentcdodds.com/blog/why-i-never-use-shallow-rendering">shallow rendering is an anti-pattern</a>, and that&#x27;s probably the reason of enzyme getting &quot;discontinued&quot;.
Also, RTL has become the <a target="_blank" rel="noopener noreferrer" href="https://reactjs.org/docs/testing.html#tools">officially recommended framework</a> to test react components, it has become very popular, and it has even joined a wider group of testing libraries under the <a target="_blank" rel="noopener noreferrer" href="https://testing-library.com/"><code>@testing-library</code></a> organization.
The thing is that I started to use it, and I was quickly surprised with how it felt to work with it, and all the benefits it was bringing to my tests.
<h3>Benefits I have experienced</h3>
Once I started migrating the first tests I noticed some benefits:
<ul>
<li>Changing my mindset was actually easier than I thought. The docs are very well written, so it&#x27;s relatively easy to start using RTL.</li>
<li>My tests got simpler, and required less of those nasty global mocks that jest allows (I&#x27;m looking at you, <a target="_blank" rel="noopener noreferrer" href="https://jestjs.io/es-ES/docs/mock-functions#mocking-modules"><code>jest.mock</code></a>).</li>
<li>Tests were way less coupled with implementation details. I moved from testing the component props, to test what the user would see on the screen.</li>
<li>Related with previous point, I started to write my tests by looking at the screen instead of the component&#x27;s implementation.</li>
<li>Changes in source code led to fewer tests requiring to be changed.</li>
<li>A progressive migration was possible, where some tests still use enzyme and others are already using RTL.</li>
</ul>
And overall, it felt good and I have already dedicated a couple of PRs just to migrate more tests.
<h3>Challenges I faced</h3>
But of course, migrating to a new tool always comes with its own challenges, and this was not an exception. I&#x27;ll explain the main ones I have faced so far and how I tackled them:
<ul>
<li>
RTL lets you do some things in a couple of different ways, and the docs may not be super clear about what&#x27;s the recommended option.
For this I recommend reading <a target="_blank" rel="noopener noreferrer" href="https://acel.me/DCMb1">this article</a> from Kent C. Dodds, RTL&#x27;s author, which explains some common mistakes when using the library.
</li>
<li>
At first, I struggled a bit with asynchronous side effects and state changes in components, which can easily end up printing a warning like <code>Warning: An update to MyComponent inside a test was not wrapped in act</code>.
The warning also explains how you are supposed to solve this by wrapping your code in <code>act()</code>, but this warning comes from React, not RTL, and what it is not telling you is that RTL already wraps all needed operations in <code>act()</code>.
What this error usually mean is that you are not waiting for something to happen. <a target="_blank" rel="noopener noreferrer" href="https://acel.me/jnUdT">This other article</a>, also from Kent C. Dodds, explains everything you need to know about the things that can lead to this warning, and how to solve them.
</li>
<li>
Since you start testing from the user point of view, some use cases can be challenging to test without coupling with implementation details. For example, when you have a component which dynamically renders different images or icons, I used to directly check the component properties.
For this I found the best solution was to use <a target="_blank" rel="noopener noreferrer" href="https://jestjs.io/docs/snapshot-testing">jest snapshots</a>. I didn&#x27;t want to manually check which SVG was being rendered in the DOM, just that different ones were being used in every case.
<pre class="language-tsx"><code class="language-tsx">// I went from this...
test(&#x27;...&#x27;, () =&gt; {
 const wrapper = shallow(&lt;MyComp dynamicValue=&quot;foo&quot; /&gt;);
 expect(wrapper.find(FontAwesomeIcon).prop(&#x27;icon&#x27;)).toEqual(someIcon);
})

// To this
test(&#x27;...&#x27;, () =&gt; {
 const { container } = render(&lt;MyComp dynamicValue=&quot;foo&quot; /&gt;);
 expect(container.firstChild).toMatchSnapshot();
})
</code></pre>
</li>
<li>
Something very similar happens if you use some library that renders canvas. There&#x27;s no way to test that from a DOM point of view, which is what RTL does.
In my case I was using <a target="_blank" rel="noopener noreferrer" href="https://www.chartjs.org/">Chart.js</a> to render some charts, so I used <a target="_blank" rel="noopener noreferrer" href="https://github.com/hustcc/jest-canvas-mock">jest-canvas-mock</a>, which exposes a method on the canvas to see which are all the events invoked from the library.
Then I used snapshots again to verify they had the expected &quot;shape&quot;.
<pre class="language-tsx"><code class="language-tsx">// I went from this...
test(&#x27;...&#x27;, () =&gt; {
 const wrapper = shallow(&lt;MyCompWithCanvas /&gt;);
 expect(wrapper.find(Chart).prop(&#x27;data&#x27;).datasets).toEqual(...);
})

// To this
test(&#x27;...&#x27;, () =&gt; {
 const { container } = render(&lt;MyCompWithCanvas /&gt;);
 const events = container.querySelector(&#x27;canvas&#x27;)?.getContext(&#x27;2d&#x27;)?.__getEvents();

 expect(events).toBeTruthy();
 expect(events).toMatchSnapshot();
})
</code></pre>
</li>
</ul>
<h3>Conclusion</h3>
For better or worst, enzyme should no longer be considered an option. If you are starting a new project or are using it on small ones, consider migrating to RTL as soon as possible.
If you are using it in bigger projects, following the process described in this article will probably help you.
In any case, you will get surprised. React testing library is a great tool and provides many benefits over enzyme.
Its main issue is that it&#x27;s not a drop-in replacement for enzyme, so you will have to change a bit your mindset.

Recently ReactJS v18 was released. I started to look into its improvements, and checked which of my projects could benefit from them. The main react-based project I maintain at the moment of writing this article is shlink-web-client, so I naturally created a new branch and started the process.

The…

My experience migrating from enzyme to react testing library

Capturing code coverage for a test suite is a very useful way to know which parts of your source code are actually getting executed by tests. This is useful not only to know if you need to add more tests to your project (in case the coverage is too low), but also, if you want to apply technics like…

Capturing remote code coverage in API tests with PHPUnit

I have spoken many times at this blog about dependency injection, and how the ZF2 ServiceManager is one of the best tools to solve it. You can read these related articles to know more: How to properly use the Zend framework 2 service manager as a dependency injection container Advanced usage of…

Improve dependency injection in PHP apps with Zend Framework plugin managers

It&#x27;s well known that using autoincrement identifiers for resources in a public API is not a very good idea, since you are exposing too much information about the size of your database and your business in general.
The PHP community is recommending to better use UUIDs these days, because it hides that information and can be generated anywhere and still be unique.
It has a number of advantages. The first one, as I already said, is the fact that it hides critical information of the system when you have to publicly share it, it is not easy to find out anything about the application business if you only have a UUID. But there are more:
<ul>
<li>A UUID (Universally Unique IDentifier) is universally unique. That menas that it is not unique only in the scope of a table, like an autoincrement, but unique accross any system in the world.</li>
<li>Since it is globally unique, it can be generated before being stored in the database or even in client-side, and we can be sure (almost) it won&#x27;t be duplicated.</li>
<li>Allows to easily migrate and merge information from different tables and databases, by keeping their identifier, since it will still be unique.</li>
<li>Decouples your application with the persistence layer, since all the information is generated before being persisted. (Thanks to <a href="https://twitter.com/tomas2387/status/658237457117368320" target="_blank">@tomas2387</a> for mentioning this)</li>
</ul>
I&#x27;m going to explain now, how to take advantage of UUIDs when working with databases in PHP applications by using Doctrine and the fantastic <a target="_blank" rel="noopener noreferrer" href="https://github.com/ramsey/uuid">ramsey/uuid</a> package, with the bridge library <a target="_blank" rel="noopener noreferrer" href="https://github.com/ramsey/uuid-doctrine">ramsey/uuid-doctrine</a>.
<h3>Creating entities</h3>
Entities will have an ID, but instead of setting them with an autoincrement strategy and an integer type, we are going to use the uuid doctrine type and typehint the ID as a <code>Ramsey\Uuid\UuidInterface</code>.
We are also going to initialize the ID in the entity&#x27;s constructor. Once the entity is created, it will have an ID, generated outside the database, but unique, so we can safely persist the entity.
<pre class="language-php"><code class="language-php">namespace Acelaya\Blog\Entity;

use Ramsey\Uuid\Uuid;
use Ramsey\Uuid\UuidInterface;

/**
 * @Entity
 * @Table(name=&quot;user&quot;)
 */
class User
{
 /**
 * @var UuidInterface
 *
 * @Id
 * @Column(type=&quot;uuid&quot;)
 */
 protected $id;
 /**
 * @var string
 *
 * @Column(length=256)
 */
 protected $username;
 /**
 * @var string
 *
 * @Column(length=256)
 */
 protected $password;
 /**
 * @var string
 *
 * @Column(length=256)
 */
 protected $fullName;

 public function __construct()
 {
 $this-&gt;id = Uuid::uuid4();
 }

 // Getters and setters...
}
</code></pre>
As you can see, we don&#x27;t have to set the <code>@GeneratedValue</code> annotation in the <code>id</code> property, since the value is not generated in the database. Instead, it is initialized in the contructor.
<h3>Registering the type</h3>
The last example is very simple. We don&#x27;t have to do anything, and our <code>id</code> will be a <code>Ramsey\Uuid\Uuid</code> instance, so we can compare it with other UUIDs and serialize it in many ways, but Doctrine doesn&#x27;t know how to serialize and deserialize that field while exchanging data with the database. We need to register the uuid type.
<pre class="language-php"><code class="language-php">use Doctrine\DBAL\Types\Type;
use Ramsey\Uuid\Doctrine\UuidType;

// Some kind of bootstrapping...

Type::addType(&#x27;uuid&#x27;, UuidType::class);
</code></pre>
Once this is set, we can use the uuid doctrine type for any property and it will be properly serialized/unserialized. We just need to initialize those properties in our entities&#x27;s constructors with the desired UUID version.

It's well known that using autoincrement identifiers for resources in a public API is not a very good idea, since you are exposing too much information about the size of your database and your business in general. The PHP community is recommending to better use UUIDs these days, because it hides…

Using UUID identifiers for databases in PHP projects with Doctrine

One of the trending topics in the PHP world nowadays is the one about microframeworks. It started some years ago with <a target="_blank" rel="noopener noreferrer" href="http://www.slimframework.com/">Slim</a> and <a target="_blank" rel="noopener noreferrer" href="http://silex.sensiolabs.org/">Silex</a>, but recently it has been an explossion of new microframeworks.
First, Slim&#x27;s team announced the third version of its own framework, which implemented the psr-7 HTTP standard by taking advantage of the middleware concept. The previos version works with Middleware too, but psr-7 looks to be designed to be used with middleware.
Then, Laravel launched the <a target="_blank" rel="noopener noreferrer" href="https://lumen.laravel.com/">Lumen</a> project, which is another microframework based on Laravel components, similar to Silex, which is based on Symfony components.
And finally, Zend framework&#x27;s team launched <a target="_blank" rel="noopener noreferrer" href="https://github.com/zendframework/zend-expressive">Zend Expressive</a>, which is similar to Slim 3 in the fact that it works with middleware and psr-7, built on top of <a target="_blank" rel="noopener noreferrer" href="https://github.com/zendframework/zend-stratigility">zend-stratigility</a> and <a target="_blank" rel="noopener noreferrer" href="https://github.com/zendframework/zend-diactoros">zend-diactoros</a>.
Recently, after playing with Slim 3 and Zend Expressive, I decided to use the last one to rebuild my website, which used to be a ZF2 application.
It is open source and you can find it <a target="_blank" rel="noopener noreferrer" href="https://github.com/acelaya/website-expressive">here</a>.
<h3>Why microframeworks</h3>
I have said several times that composer has completely changed PHP. Now it is possible to access to any package or component in any application, which is a really big advantage. You don&#x27;t have to stick to certain framework&#x27;s implementation if there is another one that you like better.
That&#x27;s made possible to start working with a framework that doesn&#x27;t have a solution for everything, and your poroject can still scale thanks to the fact that composer gives you access to almost anything.
There is where microframeworks have their power.
Also, having in mind that every time more and more packages depend on common abstractions (like the psr abstractions, psr-3 or psr-7, or the new <a target="_blank" rel="noopener noreferrer" href="https://github.com/container-interop/container-interop">container interop</a>), those small frameworks can work with many existing powerful components.
<h3>Why Zend Expressive</h3>
The first thing that I liked in Zend Expressive is that it doesn&#x27;t force you to use an implementaiton for common tasks.
The router, the templates engine and the service container are based on abstractions, which means that you can virtually use whichever fits you the most. It comes with support for two or three of each one, but you could integrate any third party component by implementing an interface.
Also, since this framework has been created by the ZF team, it comes with support for ZF2 components, which I am more used to. Specially I like to be able to use the <code>Zend\ServiceManager</code>, like in Slim 3.
<h3>Configuration driven apps</h3>
All of the microframeworks that I&#x27;ve already mentioned have something in common. They work on top of the main <code>Application</code> object, which usually implements methods to define routes and add middleware.
For example, in Slim 3, you can do something like this to dispatch a request:
<pre class="language-php"><code class="language-php">$app = new Slim\App();
$app-&gt;get(&#x27;/hello/:name&#x27;, function ($req, $res, $args) {
 echo &#x27;Hello, &#x27; . $args[&#x27;name&#x27;] . &#x27;!!&#x27;;
});
$app-&gt;run();
</code></pre>
The same thing can be done like this with Silex:
<pre class="language-php"><code class="language-php">$app = new Silex\Application(); 
$app-&gt;get(&#x27;/hello/{name}&#x27;, function ($name) use($app) { 
 return &#x27;Hello, &#x27; . $app-&gt;escape($name) . &#x27;!!&#x27;; 
}); 
$app-&gt;run(); 
</code></pre>
And also, with Expressive, you do it like this:
<pre class="language-php"><code class="language-php">$app = Zend\Expressive\AppFactory::create();
$app-&gt;get(&#x27;/hello/{name}&#x27;, function ($request, $response, $next) {
 $response-&gt;write(&#x27;Hello, &#x27; . $request-&gt;getAttribute(&#x27;name&#x27;) . &#x27;!!&#x27;);
 return $response;
});
$app-&gt;run();
</code></pre>
It is very similar in every case, and it is good enough for prototyping and small applications. However this is not my favourite approach. I prefer to use the service container as the main object, and fetch the <code>Application</code> in the front controller as a regular service. The best microframework to work like this is Expressive.
For example, in my website, the front controller looks like this.
<pre class="language-php"><code class="language-php">chdir(dirname(__DIR__));

// [...]

/** @var Interop\Container\ContainerInterface $container */
$container = include &#x27;config/container.php&#x27;;
/** @var Zend\Expressive\Application $app */
$app = $container-&gt;get(Zend\Expressive\Application::class);
$app-&gt;run();
</code></pre>
This approach allows me to define some configuration files that are consumed by factories while creating services, and the Application object is treated like another Service, injecting middlewares and routes from config files.
You don&#x27;t even have to define the factory yourself, since Expressive includes an <code>ApplicationFactory</code> that can be registered and it fetches the outstanding configuration for you.
Another cool thing in Expressive is that the <code>Application</code> itself is middleware, and so, it can pipe nested <code>Applications</code>. It also treats routes as a middleware that is registered to be resolved as a result of certain route, instead of being resolved for every route.
So, in Expressive, everything is middleware lazily fetched from a service container to dispatch HTTP requests.
<h3>Router</h3>
Currently, Expressive includes implementations to integrate with three routers. <a target="_blank" rel="noopener noreferrer" href="https://github.com/auraphp/Aura.Router">Aura.Router</a>, <a target="_blank" rel="noopener noreferrer" href="https://github.com/nikic/FastRoute">FastRoute</a> and <a target="_blank" rel="noopener noreferrer" href="https://framework.zend.com/manual/current/en/modules/zend.mvc.routing.html">ZF2 MVC router</a>. The first is used by default.
For small applications like my website, any of them should be good enough, but I needed routes to support optional params at the beginning of the path (the language). Neither Aura.Router or FastRoute do it, so I had to stick with ZF2&#x27;s router in combination with a custom Segment route that allows to skip certain parts of the route, otherwise I would have been forced to define the same route with different names, which would have made assembling routes with param inheritance much harder.
The fun thing is that Slim&#x27;s router does support optional route params at the beginning of the path, at least in version 2. Maybe I try to integrate it in the future with Expressive, since I don&#x27;t need all the power provided by ZF2&#x27;s router.
<blockquote>
Update 2015-09-20: I have finally created a Slim&#x27;s router integration library and I&#x27;m now using it. You can find it here <a target="_blank" rel="noopener noreferrer" href="https://github.com/acelaya/expressive-slim-router">https://github.com/acelaya/expressive-slim-router</a>.
</blockquote>
To make a router other than Aura.Router to be automatically injected in the Applicaiton when using the container&#x27;s <code>ApplicationFactory</code>, you need to register a service with the <code>Zend\Expressive\Router\RouterInterface</code> name.
<h3>Template engine</h3>
Similarly to the routers, Expressive works with an abstraction layer which eases the task of using any template engine with it. It comes with <a target="_blank" rel="noopener noreferrer" href="http://twig.sensiolabs.org/">Twig</a>, <a target="_blank" rel="noopener noreferrer" href="http://platesphp.com/engine/">Plates</a> and <a target="_blank" rel="noopener noreferrer" href="http://framework.zend.com/manual/current/en/modules/zend.view.quick-start.html">Zend\View</a> integration, using the second one by default, but it shouldn&#x27;t be hard to use anyone else, like <a target="_blank" rel="noopener noreferrer" href="http://laravel.com/docs/5.0/templates">Blade</a>.
I have used twig for my website, because I&#x27;ve been using it lately, and I really like it.
The template engine will be injected in the Applicaiton by fetching the <code>Zend\Expressive\Template\TemplateInterface</code> service.
<h3>Service container</h3>
The service container is very important in Expressive. All the services, middlewares and configurations are fetched from it. Expressive expects an <code>Interop\Container\ContainerInterface</code> object, which is implemented by the most used service containers (or dependency injection containers if you prefer so).
Documentation on how to use <a target="_blank" rel="noopener noreferrer" href="https://framework.zend.com/manual/current/en/modules/zend.service-manager.html">Zend\ServiceManager</a>, <a target="_blank" rel="noopener noreferrer" href="http://pimple.sensiolabs.org/">Pimple</a> and <a target="_blank" rel="noopener noreferrer" href="https://github.com/auraphp/Aura.Di">Aura.Di</a> is included in the project. Depending on how big you expect your application to become, you can use one or another, but you should be able to replace it in case of need.
If no container is provided, the Application will use the first one. Also, it has been my choice, and as I said earlier, everything in my website&#x27;s project is managed by the ServiceManager, even the <code>Application</code> object itself.
It&#x27;s one of my favourite PHP components and I use it whenever I can.
<h3>Error management</h3>
Another thing that any framework has to provide is a way to catch requests to invalid routes or uncaught exceptions and errors. In Expressive that&#x27;s made by the so called <code>FinalHandler</code>.
By default it just displays plain text errors, and returns the proper status code (404 or 500). If you want certain template to be rendered, you have to register a <code>TemplateErrorHandler</code> in your container, via the <code>Zend\Expressive\Container\TemplatedErrorHandlerFactory</code>. It will use a configuration block to know which template has to be rendered in each case, and use the registered template engine to render them.
In development, a <code>WhoopsErrorHandler</code> can be used too. It extends the functionality of the <code>TemplatedErrorHandler</code> by using <a target="_blank" rel="noopener noreferrer" href="https://filp.github.io/whoops/">Whoops</a> to display nice errors. Make sure to never use it in production.
<h3>Other considerations</h3>
You know now how to use the main components in the framework, but you need to know how <a target="_blank" rel="noopener noreferrer" href="http://www.php-fig.org/psr/psr-7/">psr-7</a> works and how to use middleware. You should read these articles if you are not familiar with those concepts, since the whole framework is built on top of them.
<ul>
<li><a target="_blank" rel="noopener noreferrer" href="https://mwop.net/blog/2015-01-26-psr-7-by-example.html">PSR-7 By Example</a></li>
<li><a target="_blank" rel="noopener noreferrer" href="https://mwop.net/blog/2015-01-08-on-http-middleware-and-psr-7.html">On HTTP, Middleware, and PSR-7</a></li>
</ul>
You should also take a look at the official documentation. It is not very long and it&#x27;s very well structured. <a target="_blank" rel="noopener noreferrer" href="http://zend-expressive.readthedocs.org/en/stable/">https://zend-expressive.readthedocs.org/en/stable/</a>
<h3>Conclusion</h3>
Those are all the things that can be done with Expressive. It could seem too basic, but it is also very extensible via composer. That&#x27;s its forte.
Probably, for my website I could have used any other microframework (Indeed I was planning to use Slim 3 before Expressive was launched), but I liked Expressive from the beginning and decided to go with it despite it is not stable yet.

One of the trending topics in the PHP world nowadays is the one about microframeworks. It started some years ago with Slim and Silex, but recently it has been an explossion of new microframeworks. First, Slim's team announced the third version of its own framework, which implemented the psr-7 HTTP…