Posts by Michael Murphy

Partials Should Never Contain Instance Variables

It may seem that the benefits of partials in our Rails application are endless. They help keep our views DRY, organized, and easily reusable. But with great power comes great responsibility.

Due to the flexibility partials give us, controlling the data flow to partials should not be an oversight. Let’s say we’re using one partial in two separate views which will render a message on the page:

Since @message in used in the partial, we must define the variable in both the Dashboard and Photo controllers. If we want to change @message to another name in one of our controller actions, then all other instances of @message must be renamed as well. For this reason, our partial becomes difficult to reuse and manage.

To combat against an issue like this we can use local variables:

You’ll notice just after the file name, we are adding an additional option which is our local variable. We can now set message to whatever we want, and then use the message local variable within our partial.

This method now allows us to use the partial freely across all our views without the worry of having to trace our variables back to multiple controllers.

For situations where you may have more than one local that needs to be passed along to a partial, just use the locals hash locals: { }.

So next time you find yourself working with partials, remember, a good practice when passing data to your partials is to use locals over instance variables.

For more best practices about rendering partials, the Layouts and Rendering section in Rails Guides is a great starting point.

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How I fixed SQL Server WMI Service Error

Recently I switched my database over to SQL Server, which led me to use Microsoft’s SQL Server Management Studio. During the installation process I ran into a WMI Service Error; something I never faced before. This is how I fixed this error and continued on with the SQL Server setup installation.

So assuming you Google searched your way over to here, I’m guessing you have a Windows Management Instrumentation (WMI) service failed error. If you do great, you may have come to the right place.

(Disclaimer: Try these steps at your own risk. What worked for me, might not work for you. I solved my issue with a series of tutorials that may or may not have contributed to this fix. I’m also not a computer genius, half of the time I had no idea what would happen. All I know is that these steps eventually worked. So proceed with this in mind.)  

WMI Service Error… you suck!

During the ‘Global Rules’ stage of your setup, you notice that your Windows Management Instrumentation (WMI) service has failed and you cannot continue until the the failure is corrected.

Windows Management Instrumentation (WMI) service Failed / WMI Service Error

What does this mean? Well, it can be caused from one or more issues on your local computer (corrupted files, an incomplete install or uninstall of a program, improper deletion of hardware, etc.).

By clicking on the ‘Failed’ link we can see detailed information. This message doesn’t give us any surprising information.

Rule "Windows Management Instrumentation (WMI) service" Failed / WMI Service Error

After a quick Google search, I managed to locate where to find the WMI service on my local computer. Here is the full path starting from the Control Pannel:

Control Pannel > System and Security > Administrative Tools > Services > scroll down to Windows Management Instrumentation

Once I located the WMI service, I noticed that the status was set to Running…

Windows Management Instrumentation (WMI) service / WMI Service Error

I found this to be strange since it appears to be running just fine. So why am I getting a WMI Service Error?

I checked the properties by double clicking (or right-click > properties) and checked the Dependencies tab…

Windows Management Instrumentation (WMI) service Properties Dependencies / WMI Service Error

Well there’s our problem. A propertly working WMI should look like this.
(Note: If your error box says “WMI: Initialization failure” take a look at this quick fix tutorial)

With a quick Google search, I came across a Microsoft blog post about rebuilding the WMI repository.

The first action they recommend to do is “Re-register all of the dlls and recompile the .mofs in the wbem folder and re-registering WMI Service and Provider”. (Whatever that means…sure, I’ll give it a try) To do this we first must create a batch file to run in the admin command prompt.

Copy the following script and paste it into notepad. Then save the file in a familiar location with the name WMI-repo-register.bat . Make sure when you save the file, you select ‘All Files’ in the ‘Save as type’ select dropdown.

@echo off
sc config winmgmt start= disabled
net stop winmgmt /y
cd %windir%\system32\wbem
for /f %%s in (‘dir /b *.dll’) do regsvr32 /s %%s
wmiprvse /regserver
winmgmt /regserver
sc config winmgmt start= auto
net start winmgmt
for /f %%s in (‘dir /s /b *.mof *.mfl’) do mofcomp %%s

Now open your command prompt (as admin) and CD to the following path; C:\Windows\System32\Wbem (chances are you’re already there when you start up CMD). Now run the file you just created in the command prompt.

Once the script completes, restart your computer and run winmgmt /verifyrepository in your command prompt. This will check the repository for consistencies.

WMI repository verification failed 0x80041002 WMI Not Found / WMI Service Error

If you get a more successful response than the one above, try running the SQL Server installation/setup again and see if the ‘Global Rules’ step passes. If you got the same response I got, continue on with the tutorial.

Next I tried resetting the WMI repository by running Winmgmt /resetrepository in the command prompt.

WMI repository reset failed 0x8007041B / WMI Service Error

Great another error… Something is blocking me from running the command. Thanks to a blog post by Robin at Fixing Things, there is a way to force a reset repository command.

Open up Windows Powershell as an admin and type the following in the command line…

Stop-Service winmgmt -Force; winmgmt /resetrepository

After the command completes, reboot your computer.

I then ran the SQL Server installation/setup and WMI services finally passed! (Forgot to take a screenshot during my excitement)

If you run into any other issues later on in the installation, (most likely in the Feature Rules) read the error and download whatever you may be missing. In my case, I was missing Microsoft .NET Framework 3.5 Service Pack 1…. so I just downloaded the pack right from Microsoft and was allowed to proceed.

Rule "Microsoft .NET Framework 3.5 Service Pack 1 is required" failed / WMI Service Error


I hope this tutorial helps you solve your Windows Management Instrumentation (WMI) service error. If you ran into a similar issue and found a different solution that worked for you, please post a link or suggestion in the comments below.

Thanks for reading!

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Year To Code…2015 Coding Goals

It was just over 6 months ago when I wrote my first functional ruby program. Sure, it was a simple question/response program, but I was exhilarated with what I created. Fast forward to now and I’m proud to be employed as a full-time software developer at a company I love working at.

The journey to reach this point was no cake walk, but by setting short term target specific goals I was able to persevere without being bogged down from the pressure of reaching my main goal; landing a software developer position.

Since this is my first January 1st as a developer, I wanted to set a few goals for myself to accomplish throughout the year. To some, if not most of you, this list may already be part of your routine, if not then you’re welcome you to recycle some of these aspirations as part of your own for 2015.

Attend more networking events

During the first 3 months of coding I was pretty active when it came to showing up to events within the programming community. Then a month after graduating my bootcamp and landing a job, I stopped going to events. To put it simply…I got lazy.

In 2015 I want to attend at least two meet ups a month. Boston has a great Ruby community, The Boston Ruby Group, and using to find an event that fits your schedule makes it that much more convenient.

Participate in a hackathon

Looking back over the past 6 months I can recall multiple instances where impostor syndrome got the best of me. I can now laugh at most of the things that cut my confidence in half, realizing how ridiculous my concerns and doubts once were.

The thought of participating in a hackathon where experienced developers are depending on my rookie code is slightly intimidating. Being a competitive person myself, I can understand why a more senior hack team would *sigh* to have me on their team. However, I’m hoping to surprise myself along with my future teams and rise to the occasion.

Work on more passion projects

The last three weeks of my bootcamp I dedicated 8 hours a day on my passion project. The same feeling of accomplishment from the simple Ruby program came back those last few weeks. To me, taking an idea and turning it into a functional program still seems like magic, but now I’m the magician.

Right now, I have two passion projects I want to work on. I’ve procrastinated far too long on potential projects that those past ideas have faded into nothing. This year my goal is to start working on a project as soon an idea comes to mind and devote more of my free time to progress them.

Take a codecation

One of my mentors; Ben Orenstein wrote a post about why a developer should consider taking a codecation. For the lazy… A codecation is a time where you travel with a couple code buddies and spend a majority of time coding on a collective passion project.

This concept of working on vacation seemed a little weird to me at first, but after some consideration, I realized it’s a great opportunity to learn and work collectively with familiar faces.



Wrapping Up…

If you have a couple goals you wish to accomplish over the course of the year I encourage you to try writing them down or creating a similar blog post. For those of you like me who make a bunch of new years resolutions at the start of the year, only to last a month before falling back on to old habits, let your blog post be your training partner who is there to motivate you when you feel like giving up.

To all of you who read this far down… Happy New Year and make 2015 your best year yet!

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Magical Values

When writing code ALWAYS be aware of magic numbers.

You attend a magic show and for the magician’s last trick he performs the old ‘rabbit out of hat’ stunt. As you sit in your seat, you witness the magician actually pull a live rabbit out of the hat he’s been wearing all night! You are stunned, but more so confused where that furry little creature came from in the first place.

Reading poorly written code can often time’s feel like you’re trying to figure out a magic trick. In this post we will cover a strategy that will combat against magical values.

So let’s talk about what magic values are. In its simplest term, a magic value is a value that is directly used within your code that has no context of where it came from.

Take a look at the example below. Can you spot a line that could possibly raise a red flag?

The area we are concerned about is within the conditional. More specifically the integer 5 is our example of a magic value.

Although this chunk of code will work, it’s not the way experienced developers write code.

The developer who wrote the lines in the example will understand it perfectly today and maybe even tomorrow, but what if he/she comes back a year from now to refactor their code? Will he/she be able to remember what 5 means? Better yet, let’s think about other developers who may be working on this chunk of code today. They may have no idea what this integer 5 is trying to perform.

Now I understand that this example is very basic, but we want to get in the habit of writing code in a way that it can speak for itself. That way everyone including yourself stays informed and happy.

Let’s take a moment and refactor our conditional in a way that we can eliminate our magic number.

As you can see in the example above, we extracted the integer 5, and set it to a constant variable outside of the method. Now we can use this constant multiple times within the class, just by calling the constant variable’s name. This is great practice because if we wanted to change the minimum username length to 6, we only have to change one bit of code instead of multiple bits in multiple locations.

The naming of the constant variable is key. A properly named variable will give us information about what the value is trying to accomplish. After all, what’s the point of extracting the magic value if our variable is poorly named?

Here is another example of a magic values, but this time we see both integers and strings:

What does (1..12) and (“a”..”z”) mean? In the example above we do not have the slightest clue. But when we refactor our class, and get rid of the magic values the code instantly becomes more clear:

Take away points:

  • Never write code with non-descriptive values
  • When defining what a value is, set it to a constant variable
  • Make sure your constant variables are properly named
  • Always look for ways to improve readability for yourself and others


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