Monday, August 29, 2016

Stepping Backwards From AngularJS to jQuery - An Experiment

Do Javascript frameworks like AngularJS matter that much when it comes to single page applications?  After more than a year of ups and downs with Angular, it was time for me to explore this question.  To do so, I wrote a little note application.  This was going to be done with just jQuery with Handlebars.js being added in later.  Here are some thoughts about that experience.

The Ajax Aspect

Ajax is important to much of what I do in my projects.  Headers and JSON get sent back and forth a lot.  Also, there are plenty of callbacks for dealing with stuff from the server.

So how do Angular and jQuery compare in that department?  To be honest, you don't lose much.  You go without Angular's $http service but you still have jQuery's ajax function to work with.  Here's what a json-in-json-out scenario looks like in AngularJS.

Here's the same thing but done with jQuery.

Overall, the only significant feature here is that $http has to be dependency injected.  I don't know that I gain anything from grabbing a service from out of whatever container it happens to comes from.  It feels vaguely like working with a Spring container in an enterprise Java project.  But that's about it for me.

Know Thy DOM

Giving up Angular did force me to think more about the DOM.  Vanilla jQuery doesn't insert itself as readily into HTML code as an Angular directive can.  That fact made direct DOM dealings more important.  For examples, here's how you generate bullet point list in Angular.

Doing the same thing in jQuery, you get something that looks like this.

While trivial in this example, string concatenation can gets messy as the HTML gets more involved.  However, you do get that upshot in jQuery of having debugger features more conveniently available.  Setting a breakpoint in straight Javascript is easy.  I have no idea how to do that with an ng-repeat loop.

Filling The Template Void with Handlebars.js

The good news is that living without Angular doesn't mean giving up on client-side templates entirely.  It turns out that Handlebars.js fills that void nicely.  Drop a template between script tags.  Load it up.  Insert the data.  All is well.

Yes, there is DOM dirty work to do but that's okay.  At least there isn't that error-prone process of piecing strings together so much.  That's actually pretty nice.

My Dynamic Button Trip Up

One area that tripped me up with Handlebars was button handling.  Buttons for deleting and changing notes are specific to each note.  The event handlers for those buttons need to reflect that.

Handlebars is really good at taking data text and plugging it into template text.  Where it gets weird is when events come into the picture.

The thing is this.  You generally don't attach event handlers directly to the text that Handlebars generates.  You attach them to some kind of DOM object like this...


Okay, so what to do?

Here was my solution.  Let Handlebars do the whole template thing.  Have jQuery wrap the text up as a DOM element.  Then, just let jQuery attach event handlers to that.  Here is what that code ended up looking like.

So that gets the job done.  Once the DOM is created, we can attach a DOM button to that structure.  And that's it.  In case you're curious, you can find the full js file where this is set up over here.  And if I'm "doing it wrong", feel free to yell at me in the comments section.

Final Thoughts

Going without Angular was nowhere near as hard as I thought it would be.  The Ajax parts are reasonable thanks to the core jQuery libraries.  The DOM aspects I found myself needing to handle really weren't that burdensome.  And thanks to Handlebars, I didn't even have to give up templates.

What Angular is good for is catering to my enterprise and Java background.  I've done my share of mixing logic and HTML together from my experiences in JSP and ColdFusion.  The dependency injection that happens in Angular feels like a simplified version of what happens in a lot of Spring projects.

All being said, I don't think I'm going to disavow AngularJS entirely because I'm still not convinced that it's a "bad" framework.  For bigger web applications, it might well be ideal for all I know.  It's just that I now know that the set of problems Angular fits for isn't as big as I thought.  And that's an okay thing to come to terms with.  Here's to the programmer's journey!

Monday, August 8, 2016

Python and Javascript Jam Session - A Web Interface for Apt-Cache

Just fun fun.... How easy is it be to make a web interface over the apt suite of tools?  That's what AptPackageShow seeks to explore.  This post will cover aspects of this project that I personally found to be interesting.

Technically, this is not a FUMBLINA project.  The Debian packaging system is already a database of sorts.  No need to drag MySQL into it.  So scratch the M out of the acronym for this project.  No biggie.  There's still plenty of neat stuff to check out.

Building The API

So the first thing to fire up a Python editor to put together an api.  Starting with a file means a short path from coding to seeing actual results.  Said results might be in a terminal shell but that still counts for something.  

For this model interface, we'll work with parts of apt-cache.  The "search", "show", and "stats" sub-commands are of interest here so we build functions to interface with them.  

A lot of the implementation details of the api is just Flask boilerplate and manipulating of string, dictionaries, and lists.  It's fun to do but, to be honest, it's pretty boring to talk about.  The most I can say on that matter is don't do things like this....

That's pretty bad.  If you must write code like this, make sure you refactor it ASAP.  Future You will thank you for it.

Working The Subprocess Module

The check_call function from the subprocess module is a key ingredient for this project.  Here's an example of this....

There are a few takeaways from this experience with invoking outside processes in this way.

  1. If you have to make calls in a context where you'd normally need shell access, set the shell=True option.
  2. Using absolute paths for commands simplifies things.
  3. If you deploy to a test server, make sure the running Python process uses an account with shell permissions.
Someone on Reddit pointed out the shell=True thing in point 1 isn't true.  Setting shell=False actually does turn out to work just fine.  You only need make it True if you run commands that are shell specific.

One last thought on this subtopic.  Running something like this in production feels wrong.  We are allowing shell access to a process that gets information directly from the user.  That strikes me as kind of a bad thing.  So in no way should this be considered an example of secure code.

Building Up An AngularJS Interface

Time to switch from Python to Javascript.  There's this idea that a component style to Angular code means fewer headaches with respect to where your data is available.  This isn't wrong but it isn't completely true either.  For example, component hierarchy for this project looks like this.....

And then there is the thing about having to wire together variables like this....

From there, you're supposed to pass info on like this....

So there's a lot of wiring to think about when you trade your scope hierarchies for component hierarchies.  Those can still be painful in the same way that ANY code hierarchy is painful.  That's why "search results" and "package details" are part of the same component.  It helps keep the hierarchy flatter.

Last Thoughts

What's the point of all this?  This was a fun diversion mainly done out of curiosity in the "What does this button do?" sense.  Having gotten practical experience with Angular components from this, I regret nothing.  I hope you enjoyed reading this little spiel about my project.  Again, go here if you want to see the project for itself and/or play with it.  Have fun!

Tuesday, August 2, 2016

Making Things Within The Quadrants of Want

"The way to get startup ideas is not to try to think of startup ideas. It's to look for problems, preferably problems you have yourself.  The very best startup ideas tend to have three things in common: they're something the founders themselves want, that they themselves can build, and that few others realize are worth doing. Microsoft, Apple, Yahoo, Google, and Facebook all began this way." - Paul Graham - How to Get Startup Ideas

My motivations for Flashmark were based on this essay.  It is a tool aimed at my learning issues.  I wanted this for myself.  However, recent attempts to market it drew little interest.  Nobody tried it.  Nobody commented.  I'm mostly okay with this!  But it did get me thinking of the whole idea of building software people want.

The Four Quadrants Of Want

There are four kinds of "want" when it comes to a software product.

Quadrants Of Want

Quadrant 1.) The developer wants it and the users want it.

This is ideal.  The developer is a user and other people use it too.  Mark Zuckerberg has a Facebook account as do over a billion other people.  There is also the case of the smaller developer who uses her own SaaS product but also has a couple hundred paid subscribers.  Whatever the scope of your user base is, this is the best quadrant to be in.

Quadrant 2.) The developer doesn't want it but the users do want it.

This isn't a bad deal either.  You have no dog in the fight when it comes to the product.  Still, users like it enough to pay which means you get paid too.  I've worked on software for archiving airplane part drawings and tracking phone tolls in office telephone systems.  I have no personal interest in planes or phones.  Still, the process of working on these things was enjoyable and co-workers were awesome.  These were good gigs.

Quadrant 3.) The developer wants it but the users do not want it.

This has happened for me twice with Flashmark being my most recent instance of this.  In the past, the Uncle Squirrely was a project I did that notified me of videogames that just dropped to "greatest hit" price levels.  In neither case did these projects get anything in the way of a user base.  But I didn't care.  I was scratching my own itch.  It didn't matter whether or not others had an itch in that same spot.

Quadrant 4.) The developer does not want it and the users do not want it either.

This is what Paul Graham wants people to avoid.  It happens when you don't want the product but you THINK other people will buy into it.  When they don't, the end result feels like a waste of time.  Pure demoralization.  Graham felt it first hand and would rather other startups not be crushed by that same defeat.

Moving Between Quadrants

When you start in quadrant 3, you are guaranteed a user.  It is you.  You are a worthy customer base to develop a quality product for.  Know it.  Believe it.  Even if the product never leaves this zone, you are at least spared the quadrant 4 nightmare scenario.

Quadrant 3 projects can serve as potential gateways to quadrants 1 and 2 if you allow it.  The key thing here is to be open.  Share what you are do as early and often as possible.  This allows for feedback for improvements.  It could lead to a new job.  It could make your project profitable.  But most importantly, feedback makes projects more fun.  You'd be out of your mind to not want to up the fun factor!

Practicing What I Preach

Don't do what I did with Flashmark.  There was very little communication with other people during that project's development.  Only two release announcements were ever made about it.  Both of them were made when the project was close to "done".  The end result is still a success.  However, I will admit it would have been nice if it were a different kind of success.

Instead, do something like this..... Last week, I started a just-for-fun project to put up a web interface to the apt-cache tool commonly found on Debian and Ubuntu systems.  I'm doing it because I'm curious.  How easy would it be to build a small AngularJS project using a component-based approach?  How would it work out if I put a Flask API on top of a command-line tool?  That's what I'm interested in finding out with the AptPackageShow project.  It's incomplete but you can go here if you want to check it out.  Comments welcome!

See the difference there?  With AptPackageShow, the conversation opens up almost right away instead of the "not talking about it much" approach taken with Flashmark.  I'm going to go out on a limb in saying that this is a better way.