Rails migrations are contextual

So sometime ago i added a foreign key column as a rails migration which creates an index on that column as well: through the add_foreign_key method. This index is of the form rails_fk_some_hex  Unfortunately i forgot to add a unique constraint with the index which was a necessary use case.

I thought ‘no big deal’ i’ll just add that now, i ran:

add_index :table_name, :column_name, unique: true, index_name: :some_name

and viola it worked on my local machine like a charm. It even removed the previous index on that column that the foreign key migration created.

but running this on staging. I had 2 indexes, 1 unique and 1 non unique -_- .

Little debugging and i could confirm a pattern:

If these 2 migrations occur in the same rails db:migrate then the add_index migration also overwrites the index created by the foreign_key migration. However in different migrations, it just adds another index.

Solution:

I’m not sure if this is a feature or a bug.  To solve for the cases where migrations run together(dev machines) or on servers where they are run separately I used remove_index if  index_exists? .

Conclusion:

This isn’t something “breaking or a huge discovery”, just something weird i found in my Rails Journey and something you should be aware about.

 

 

week full of refactor

My Project has grown a lot now, we are officially going to support  C, C++, python3, JS, CSS and JAVA with our generic algorithms, though they’ll still be experimental owing to the nature of the bears.

The past two weeks were heavily concentrating on refactoring algorithms of the AnnotationBear and IndentationBear, the IndentationBear received only small fixes while the AnnotationBear had to undergo a change in the algorithm, the new and improved algorithm also adds the feature of distinguishing between single-line and multi-line strings while earlier there were just strings.

The IndentationBear is almost close to completion barring basic things like:

• It still messes up your doc strings/ multi-line strings.
• Still no support for keyword indents.

the next weeks efforts will go into introducing various indentation styles into the bear and fixing these issues, before we move on to the LineBreakBear and the FormatCodeBear.

Exploring the world of indents

My Project so far:

The coding phase has begun and unfortunately i wasn’t able to start right away, but I had already done some part in the community bonding period and was able to work on another aspect of my project before the week got over, so now finally let me introduce you to my project which is *drumrolls* Generic Spacing Correction. I know it doesn’t sound very exciting right?But believe me the “Generic” makes it pretty exciting.

Demystifying the name, my project aims to do what you already see in most of your editor programs, be it natively or through plugins; which is automatically indenting your code. It doesn’t stop there though, it indents your code but it’ll indent it regardless the language you use! So you basically indent your C files and python files by the same algorithm! Bye-Bye ctrl + I? Maybe but there’s a lot of work to do.

See, every language style guide follows some basic rules when it comes to indentation, one of them being: there are levels of indentation and each level “means” being part of the same context.

So I just have to identify these levels. Easy. Right? Well for a particular language yes it’s not so difficult, but when it comes to managing the same for all languages out there, then the task becomes a little daunting.

Here’s how i plan to tackle these problems:

First of all my algorithm doesn’t support all languages from the start, it’d support basic languages like C, C++, JAVA maybe even ruby. This is because unlike languages like python, these languages have markers to specify when to start and end indentation.

So far i’ve been able to come up with a very basic implementation, though it still lacks features of indents based on keywords and also absolute Indentation, Like:

if(condition)
    indents

and

int some_function(param1,
                  param2,
                  param3) 

other than it works for basic indentation of blocks specified by those indent markers.       my PR has all the code to this basic indentation algorithm and is still under-review/wip.

Later on i’d like to make this algorithm configurable to the extreme.

Apart from the basic functionalities like hanging indents and whatnot, it’d be nice to have an algorithm which is configurable to all styles of indentation.

What is Style of indentation?

Apparently there are many ways of correctly indenting your code, and it’s upto
the Community what type of indentation they want to follow.

For example:

if(something){
    // code
}

if(something)
{
    // code
}

if(something)
  {
    // code
  }

all of these are ways indenting an if block. None of these is wrong and it’s
entirely up to you which style you prefer, a generic and versatile algorithm would support all three via configurations.
Sadly my basic implementation doesn’t support the third kind yet.

All in all it’s just the beginning and i’m really excited on how the project develops and what type of algorithms i’m able to deliver, hopefully i’ll be back next time with a more functional and useful algorithm.