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The &quot;version&quot; field in the package.json file can very easily become outdated, if you git-tag by mistake before publishing the package, or if pushing the changes fails after 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 It&#x27;s misleading in source code, as it can very easily be out of date.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)

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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

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Any medium and large project has to deal at some point with the problem of translating the application itself to other languages. There are many tools and standards to do this, but one of my favourite components is <a target="_blank" rel="noopener noreferrer" href="https://zf2.readthedocs.org/en/latest/modules/zend.i18n.translating.html">Zend\I18n</a>.
Everybody who knows me is aware that I love Zend Framework, but unfortunately it&#x27;s been a while since the last time I worked on a project based on it.
But nowadays that is not a problem. <a target="_blank" rel="noopener noreferrer" href="https://getcomposer.org/">Composer</a> allows you to install any component or library on any project, so I&#x27;m indeed constantly using many ZF2 components.
I&#x27;m going to explain how to use one of those components, Zend\I18n, to manage application translations, which is a component that internally uses the <code>intl</code> PHP extension, so make sure to have it installed.
<h3>Installation</h3>
As usual, this component is easily installable with composer by running this command.
composer require zendframework/zend-i18n:~2.2
If you want, I&#x27;ve created an example project that I&#x27;m going to use on this article. You can find it <a target="_blank" rel="noopener noreferrer" href="https://github.com/acelaya-blog/internationalization">here</a>, just clone it and run <code>composer update</code>.
Then go to the public directory, run <code>php -S 0.0.0.0:8000</code> and navigate to <a href="http://localhost:8000" target="_blank">localhost:8000</a>
<blockquote>
If you are not familiar with composer, take a look at this <a href="/2014/07/19/dependency-management-and-autoloading-in-php-projects-with-composer/">article</a>.
</blockquote>
<h3>Translation files</h3>
The first we need to decide is the way we are going to store translations. There are many supported formats, from plain PHP arrays where we set a translation key and the text in a language, to <a target="_blank" rel="noopener noreferrer" href="https://www.gnu.org/software/gettext/">gettext</a> files that can be automatically updated with new strings to be translated, but we could also use xml or ini files.
The preferred method when using Zend\I18n is gettext (and it would be also my choice). It is easy to configure, uses super fast binary files in production and we don&#x27;t need to define translations immediately, we can leave it for then, so that it doesn&#x27;t break the development flow.
Gettext files are usually handled with an external tool, <a target="_blank" rel="noopener noreferrer" href="https://poedit.net/">poedit</a>, an open source cross-platform application that can inspect our project and find new translations, deleted translations and updated translations, syncing our translation files (usually those with <code>po</code> extension) so that we don&#x27;t need to remember where we added or updated internationalizable texts.
To do this we just need to tell the program the name of the functions we use to translate strings (usually <code>translate</code>, <code>gettext</code>, <code>_</code> and such) and the files it needs to scan for new translations.
It also compiles and generates the binary <code>.mo</code> files, which are the ones used by the application.
<h3>The translator</h3>
Once we have decided the format of the files that are going to store translations, we have to create the main <code>Zend\I18n\Translator\Translator</code> object that is going to be used to find translations by consuming certain configuration.
In the example, the <code>src/translator.php</code> file generates and returns a <code>Translator</code> instance. You will need to register your object in some kind of service container so that you can inject it anywhere. This example is so simple, that I just included the file in the index.php.
The <code>Translator</code> has a factory method that is able to consume a configuration to generate the instance. It looks like this.
<pre class="language-php"><code class="language-php">use Zend\I18n\Translator\Translator;

return Translator::factory([
 &#x27;locale&#x27; =&gt; &#x27;en&#x27;,
 &#x27;translation_file_patterns&#x27; =&gt; [
 [
 &#x27;base_dir&#x27; =&gt; __DIR__ . &#x27;/../languages&#x27;,
 &#x27;type&#x27; =&gt; &#x27;gettext&#x27;,
 &#x27;pattern&#x27; =&gt; &#x27;%s.mo&#x27;,
 ],
 [
 &#x27;base_dir&#x27; =&gt; __DIR__ . &#x27;/../more_languages&#x27;,
 &#x27;type&#x27; =&gt; &#x27;phpArray&#x27;,
 &#x27;pattern&#x27; =&gt; &#x27;%s.lang.php&#x27;,
 ],
 ],
]);
</code></pre>
In the configuration we have to define the default locale. It can be only one or an array with many of them, so that the translator can load another language if it is not able to find the first one. The locale can be changed later, but it is a good idea to have a language by default.
Then we have to define a list of places to find translation files. Each specification must include the directory which stores the files, the format of the translations in that directory (we can mix gettext with arrays and ini files if we want) and finally the pattern used to find certain translation file. The first mask will be replaced with the locale that is being used at each moment. This way, if we try to translate a message to the locale en, in the first directory, it will look for a file with the name <code>en.mo</code>
I have not included it in the example, but we could also set a cache storage to be used with each translations directory under the &#x27;cache&#x27; key, but then we will need to install <code>zendframework/zend-cache</code> too.
<h3>Translating texts</h3>
Our translator is now ready to be used. In the example, the <code>public/index.php</code> file makes use of the translator to translate a couple strings.
The translator works this way, when you call the methods <code>translate</code> or <code>translatePlural</code> with a string, it tries to find the translation in current locale. If it does, it will return it, otherwise it will return the original string.
This way we can use the default language (usually english) for keys and avoid to generate translation files for that language.
I have configured my <code>po</code> files so that poedit looks for the usage of the <code>translate</code> method inside the public directory, and assume the first argument is the string to be translated.
At the top of the file you will see that I get a <code>lang</code> query param to use it as the current locale. If it is not defined or you define one that is invalid, the default locale <code>en</code> will be used.
Now you can test it. It has three valid locales, en, es and fr. Use them to see the texts in English, Spanish and French. You can try to use an invalid locale too and you will see the texts in english.
The last string is not included in any translation file, so you will see it always in english.
<h3>Conclusion</h3>
This is it. The translator is a simple component to use on any PHP project. It has more power in Zend Framework based applications, since it can be created by using the ServiceManager, and includes view helpers and integration with forms, but even so it can be used in isolation.
I would like to discuss about advanced concpets of the translator, like text domains, plural forms and even some kind of front-end integration to use the same translation files under javascript environments, but that will be done in another article.

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Translations and internationalization in PHP projects with Zend\I18n

Authentication is one of the most usual tasks we need to resolve in medium and large web applications.
There are many kinds of authentication. We could use database table authentication, HTTP authentication, LDAP authentication or any other kind of authentication we could imagine. Maybe we need to authenticate with a web service or by using OAuth.
The perfect solution would be to have a scalable component wich, today, let us authenticate over a MySQL database and store the session in the standard PHP session, but tomorrow can be easily changed to use HTTP authentication and store the session in a PostgreSQL database, without making big changes in our code.
Zend Framework 2 implements that in the <a target="_blank" rel="noopener noreferrer" href="http://framework.zend.com/manual/2.3/en/modules/zend.authentication.intro.html">Zend\Authentication component</a>
<h3>The Zend\Authentication component</h3>
This component has a main class, the <code>Zend\Authentication\AuthenticationService</code>, which encapsulates two adapters:
<ul>
<li>The authentication adapter, which is responsible of performing the authentication itself</li>
<li>The storage adapter, wich is responsible of storing the identity returned by the authentication adapter after a successful authentication. That identity could be any kind of data, from a simple array to a complex object.</li>
</ul>
Both of them have some predefined implementations, and we could even define our own by implementing <code>Zend\Authentication\Adapter\AdapterInterface</code> and <code>Zend\Authentication\Storage\StorageInterface</code>
As for this, we could say the Zend\Authentication component implements the <a target="_blank" rel="noopener noreferrer" href="https://en.wikipedia.org/wiki/Adapter_pattern">adapter pattern</a>, because the AuthetnicationService will never do the job, but delegate both tasks to its adapters. Changing one of the adapters should result in very little code modifications, because the rest of the application depends only in the AuthenticationService.
<h3>Installation</h3>
The easiest and recommended way to install this component is by using <a target="_blank" rel="noopener noreferrer" href="https://getcomposer.org/">composer</a>
Just run <code>php composer.phar require zendframework/zend-authentication:2.3.*</code> to get the dependency installed.
It will suggest to install other Zend Framework 2 components that you will probably need if you want to use some of the built-in adapters and storages.
<blockquote>
For more information on how to use composer, read <a href="/2014/07/19/dependency-management-and-autoloading-in-php-projects-with-composer/">this</a>.
</blockquote>
<h3>Usage</h3>
Let&#x27;s imagine we want our users to use database authentication (the provided username and password will be checked in a table, for example), and store their data in a simple PHP session.
<h4>Create the service</h4>
This could be the creation of the AuthenticationService.
<pre class="language-php"><code class="language-php">// [...]

// We have passwords hashed with password_hash in the database,
// so we need some application level logic to compare hased and plain passwords
$credentialCallback = function ($passwordInDatabase, $passwordProvided) {
 return password_verify($passwordProvided, $passwordInDatabase);
};

// Create the authentication adapter
/** @var \Zend\Db\Adapter\Adapter $dbAdapter */
$adapter = new \Zend\Authentication\Adapter\DbTable\CallbackCheckAdapter(
 $dbAdapter,
 &#x27;users&#x27;, // Table name
 &#x27;username&#x27;, // Identity column
 &#x27;password&#x27;, // Credential column
 $credentialCallback // This adapter will run this function in order to check the password
);

// Create the storage adapter
$storage = new \Zend\Authentication\Storage\Session();

// Finally create the service
$authService = new \Zend\Authentication\AuthenticationService($storage, $adapter);
</code></pre>
And that would be all we need. That code could be located in some kind of factory or bootstrap script. We could also use a dependency injection container implementation to create the AuthenticationService object.
<h4>Using the service for authentication</h4>
Then, if we need to use the autentication service to perform an authentication, this would be the code. I have created a class that could act as a controller.
<pre class="language-php"><code class="language-php">class MyController
{
 /**
 * @var \Zend\Authentication\AuthenticationService
 */
 protected $authService;

 public function __construct(\Zend\Authentication\AuthenticationService $authService)
 {
 // We should get the previously created AuthenticationService injected
 $this-&gt;authService = $authService;
 }

 public function loginAction($username, $password)
 {
 /** @var \Zend\Authentication\Adapter\DbTable $adapter */
 $adapter = $this-&gt;authService-&gt;getAdapter();
 $adapter-&gt;setIdentity($username);
 $adapter-&gt;setCredential($password);

 $result = $this-&gt;authService-&gt;authenticate();
 return $result-&gt;isValid() ? &#x27;Login OK!&#x27; : &#x27;Wrong username or password&#x27;;
 }
}
</code></pre>
As you can see, we have to set the identity (usually a username) and the credential (the password) to the adapter wrapped by the AuthenticationService, and then call to the method authenticate.
That method will return a <code>Zend\Authentication\Result</code> object which can be used to know if authentication was OK (by calling the <code>isValid()</code> method) and get the identity data (by calling <code>getIdentity()</code>).
In any case, if authentication was valid, the AuthenticationService will automatically store the identity in the sotrage object.
The identity data contents will depend on the adapter implementation. In the case of the DbTable adapter, it is an array with information of the user&#x27;s table row.
<blockquote>
For this tutorial I have avoided the database connection configuration and how we get the username and password. If you want to know how to create a database adapter (<code>Zend\Db\Adapter\Adapter</code>) in Zend Framework 2, just read <a target="_blank" rel="noopener noreferrer" href="https://framework.zend.com/manual/2.3/en/modules/zend.db.adapter.html">this article</a>.
</blockquote>
<h4>Checking a stored identity</h4>
Now that we have performed the authentication, in next requests we need to check if the user is already logged in. The AuthenticationService is also capable of that.
Since we set a PHP session storage object, it can look at that storage for a previously persisted identity. If it exists we can assume a user is already logged in.
At some kind of pre-dispatch hook, after any operation that needs atuhentication is preformed, we could do something like this.
<pre class="language-php"><code class="language-php">// [...]

/** @var \Zend\Authentication\AuthenticationService $authService */
if (!$authService-&gt;hasIdentity()) {
 $response = new Response();
 $response-&gt;setCode(403);
 return $response;
}

// [...]
</code></pre>
The Response object is a fake object I made up just for this example, but it represents that if the user is not logged in we return a 403 error.
We could also redirect him to the login form, that just depends on the situation, but as you can see, the <code>hasIdentity()</code> method tells us if some user was logged in.
<h4>Deleting a stored identity</h4>
Finally any user could want to logout from the system. The AuthenticationService allows us to destroy the stored identity by calling <code>clearIdentity()</code>, which will make the method <code>hasIdentity()</code> to return false in subsequent calls.
Let&#x27;s extend the previous <code>MyController</code> class.
<pre class="language-php"><code class="language-php">class MyController
{
 /**
 * @var \Zend\Authentication\AuthenticationService
 */
 protected $authService;

 public function __construct(\Zend\Authentication\AuthenticationService $authService)
 {
 // We should get the previously created AuthenticationService injected
 $this-&gt;authService = $authService;
 }

 public function loginAction($username, $password)
 {
 // [...]
 }

 public function logoutAction()
 {
 $this-&gt;authService-&gt;clearIdentity();
 return &#x27;User logged out successfully&#x27;;
 }
}
</code></pre>
And that&#x27;s pretty much all you can (and probably need) to do with the AuthenticationService.

Authentication is one of the most usual tasks we need to resolve in medium and large web applications. There are many kinds of authentication. We could use database table authentication, HTTP authentication, LDAP authentication or any other kind of authentication we could imagine. Maybe we need to…

Alejandro Celaya | Blog

Software development, agile methodologies and open source software.

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