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Archive for the ‘Technical’ Category

ReactJS: componentWillReceiveProps() is Dead! (*sniff*)

21 Apr

ReactJSThings evolve. ReactJS evolves. With version 16.3, there were several changes to the component life-cycle methods. In particular, componentWillReceiveProps is disappearing. In its place, they say, you can use the getDerivedStateFromProps static function. I found this a bit challenging, but I did find an interesting pattern when the component-state was dependent on fetched information.

I should mention that I had a specific goal to better encapsulate data within the component. While I could pass in all the needed data as properties, that would reqire the surrounding component know what to pass and how to get it. That shouldn’t necessarily be necessary; the component knows what it needs and how to retrieve it.

For example, say you have a component which accepts a phone number and displays the phone number and the state that it’s from. Certainly, you could write a simple component that accepts both pieces of information as properties.

<ShowPhoneLocation number="+12065551212" city="Seattle" />

Which might be implemented as:

class ShowPhoneLocation extends React.Component {
  render() {
    return (
<div>{this.props.number} is from {this.props.city}</div>
)
  } // render()
} // class ShowPhoneLocation

But, since the component should be able to infer the state from the phone number (by its area code), it shouldn’t be incumbent on its container to know what it is.

class ShowPhoneLocation extends React.Component {
  static getDerivedStateFromProps(nextProps, prevState) {
    let location = getCityFromPhone(nextProps.number)
    return {
      city: location
    }
  }
  render() {
    return (
<div>{this.props.number} is from {this.state.city}</div>
)
  } // render()
} // class ShowPhoneLocation

That’s all well and good, but what if getCityFromPhone() has to call a web service? We don’t want getDerivedStateFromProps() to stall, waiting for a response. However, it is static and does not have a this reference to the object for which it is returning state; so an asynchronous fetch doesn’t know what object’s state to set. Instead, don’t wait for the result to save in the state, save the request’s Promise in the state and update the state, once the promise resolves.

function getCityFromPhone(number) {
  return fetch('http://saas.com/get/'+number+'/city') // Returns fetch promise
}
class ShowPhoneLocation extends React.Component {
  static getDerivedStateFromProps(nextProps, prevState) {
    let location = getCityFromPhone(nextProps.number)
    return {
      city: location
    }
  }
  componentDidUpdate() {
    let location = this.state.city
    if (location instanceof Promise) {
      this.setState({ city: '...waiting...' })
      location.then(city => this.setState({ city: city }) )
              .catch(() => this.setState({ city: 'not found' }) )
    }
  }
  render() {
    return (
<div>
        {this.props.number} is from {this.state.city instanceof Promise
                                     ? '...'
                                     : this.state.city}</div>
)
  } // render()
} // class ShowPhoneLocation

In componentDidUpdate() you can define the completion handlers to set the object’s state, base on the returned information from the service.

It is a common pattern to perform a fetch in componentDidMount(). The problem is that there may not be enough information to perform the fetch, that early, or the information for the fetch changes after the component has been mounted.

I am going to miss componentWillReceiveProps() — without it, things become a bit more convoluted — but it’s going the way of the Dodo.

 

HTTP via Telnet

02 May

Okay, back to basics, the very low level basics. HTTP is text based, telnet enables a network connection via a text-based command line. All good. We can use telnet to talk to a web server by manually typing text to it, if you know the details of the content syntax to send HTTP via telnet.

Though this is not done, often, it is still good to know how it can be done. In fact, since these basics rarely change, I shouldn’t have even had to write this down, since it should be innate.

Sending HTTP Using Telnet

Once you get telnet running (see section, below), it is just a matter of typing HTTP to the server, manually.

There are four pieces the first three are shown, here:

GET / HTTP/1.1
Host: cachecrew.com
Connection: close
 
  1. This is the start of the HTTP commands you can enter. The first line must specify the HTTP method.  There are three parts: Read the rest of this entry »
 
 

Promises, Promises… Timeout!

25 Apr

I was playing with ES6’s new Promises, for the first time, this week. Then, I was looking at the ugliness of using a browser’s setTimeout() function and thought that it would look better as a Promise.

tl;dr summary: A Simple Promise Version of “setTimeout()”

If we do it right, you simply specify the timeout period and implement a handler for then() to invoke:

timeout(5000) // Delay for 5000 ms
   .then(function () {
      // Do, here, whatever should happen when the time has elapsed…
   });

Or, since this is ES6, we might as well use arrow-function shorthand:

timeout(5000).then( () => {
   // do your thing, here…
})

Implementation

The setTimeout() already functions a bit like a Promise, without matching the promise-pattern and syntax, so converting it to a Promise is pretty easy: Read the rest of this entry »

 
 

Simplicity via PHP Frameworks

05 Apr

PHP language and web-technologyA long time ago, I’d endeavored to create my own lightweight PHP framework, ccPHP. It was a good exercise, but never reached prime time. Around that time I began to notice others endeavoring to do the same thing (i.e., create simpler, lighter weight PHP frameworks that didn’t take more time to learn than to implement the project). I’ve been away for a while and things have changed.

  1. The continued refinement and simplification of frameworks.
  2. The greater emphasis on frontend apps to do more of the work that used to be done in the middle tier.
  3. The ubiquity of RESTful interfaces, the dividing line between front-ends and servers.

Micro-PHP Frameworks

I doubt that I will ever finish my own framework, now that others are a lot closer to the goals that I was moving towards. And, right now, I simply want to find a lightweight modular frameworks that truly help me get my core work done. Dragan Gaic did a great survey of the PHP hot frameworks in Top 12 Best PHP RESTful Micro Frameworks (Pro/Con).

A key feature of such frameworks is for them to be modular to allow me to pick and choose only the components I need, rather than have to install, understand, and run a bunch of functionality that I do not need. It makes it harder for the developer and impacts performance of the results. Model-View-Controler (MVC) is a common software architecture pattern. With the client side being far more capable of managing the view part, on its own, the server side can be simpler. Instead of cluttering up the server-side app with trying to display information, it can simply focus on securing data and access and providing data services via RESTful interfaces.

So, what I am looking for are pieces to help me access persistent data and build RESTful interfaces. And something to help keep all the code flow organized. Based on the article, I can look at Silex, Slim, Lumen, or Phalcon for the latter. For database access, Ive worked with RedBeans before and liked it, so I will probably pick that up again. If one of the frameworks doesnt help implement and configure a RESTful interface simply, then I may get back into the framework building business again.

Model: RedBeans
View: Frontend client
Controler: one of SilexSlimLumen, or Phalcon

A WordPress bug allowed my website to be hacked. I thought this was lost forever until I thought to reconstitute it from http://Archive.org!!

 

Solving git Problems with Prune

28 Jan

gitThe more I use git, the more I find that it is not as bullet-proof as I have been led to believe. Though, so far, there seems to always be a way out of a problem. Such is the case when I was unable to update a local branch from our

Your configuration specifies to merge with the ref 'my_branch'
from the remote, but no such ref was fetched.

No matter what I did to recreate my local branch, I could not pull from the remote. Google and StackOverflow was of no help—misdirecting to unhelpful information. It turned out that even through I’d fetched the current state of the remote server, my index was still showing a remote branch that did not really exist. Running the following command cleaned that up—and all was well:

$ git remote prune origin
Pruning origin
URL: git@github.….com:….git
 * [pruned] origin/my_branch
$ _

For some reason there was a phantom remote branch that fetch did not update in my local index, properly. Otherwise prune is pretty innocuous, so it might be worth running, every once-in-a-while to make sure that your index is an accurate reflection of the remote.

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git “Getting Started” Tips

21 Jan

git is has become one of the most popular source code control tools on the planet. Even if you’re coming from another source control system, becoming proficient with git can take some time. The best place to start is by running through the git Tutorial. Before that, you might take a look at the GitGuys article to get a quick synopsis of git concepts. Also, though slightly out of date, keeping the following diagram in front of you will help as well. It shows the git command-line commands that “move” file changes from one place to another in the git data-store hierarchy. Read the rest of this entry »

 
 

Activating OS X’s Builtin Apache Web Server and PHP

14 Jan

As I mentioned in my prior post OS X Command-line Dev Tools—Install Shortcut, OS X comes with a variety of built-in tools suited for developers. Unfortunately, Apple has seen fit to hide one of the most important of them: the web server. Despite that, they are easily unlocked if you know how. This applies to Mountain Lion (10.8) and (though I haven’t tried it, yet) Mavericks (10.9). Though you can install separate installations, I don’t like to install anything extra, unless I must. Read the rest of this entry »

 

Command line clipboard in macOS and Cygwin

03 Dec

I use the command line a lot, even though I am on a graphical user-interface like Windows or macOS. And since I’m lazy, I write a lot of scripts to perform repetitive tasks. The downside of command-line is that there is no standard way to interact with GUI features. I stumbled across a command in macOS, recently that allows command line programs to copy/paste between the clipboard that we’re so used to using.

macOS pbpaste and pbcopy

macOS has two commands, pbpaste and pbcopy, which “paste” from the pasteboard to stdout and copies from stdin to the pasteboard, respectively Read the rest of this entry »

 

Syncing Github Forks

26 Nov

GitHub_LogoGithub has become the place to manage source code—it’s free, robust, and commonly accessible. Github repositories are owned and access to change them must be enabled by the owner. Still, you can make changes to a Github repository; but a “pull request” must be sent to contributors of the repository and they can accept the change at their discretion. Keeping changes in sync when you don’t have direct change privileges may not be obvious.

One-time Github Changes Read the rest of this entry »

 

PHP Recipe to Show Source-code

19 Nov

PHP source-code display recipeHere is a simple Web 1.5 (static HTML with a little bit of styling and JavaScript) recipe to allow a viewer of your web page to see the PHP source-code, behind it, with a minimal amount of JavaScript and a little CSS manipulation—good for showing the work you’ve done to others. Or for embedding in your own source, in debug mode, so that teammates can see each others’ work.

See the example code at: http://cachecrew.com/sample_code/highlight_file.php and http://cachecrew.com//sample_code/highlight_file2.php.

The PHP and HTML Read the rest of this entry »