Category: programming

Installing nvm and node on Linux

May 6, 2022 / abhijit

I’m using PM2 for managing all the server processes. So, installing node and nvm (node version manager) is now one of the first things I do during an application server setup.

node and nvm, just like ruby and rvm (ruby version manager) are always installed under the non-root user account.

Promises and Async / Await

April 27, 2022 / abhijit

I always struggle with understanding how async / await works.

So, I decided to write the code down and refer to this rather than trying to think it though every time!

I’ll start with the simple XMLHttpRequest

var req = new XMLHttpRequest();

req.onreadystatechange = function () {

  req.onload = function () {
    if (req.status == 200) {
      console.info('success')
      var arr = JSON.parse(req.responseText);
      populatePage(arr);
    }
    else {
      console.info('error')
    }
  }
}

req.open('GET', baseURL, true);
req.send();

Here, I’m hitting baseURL (defined outside of this code) and doing something with the received array with the populatePage function outside as well.

I wrote it like this so that I don’t add other code which is not relevant to the call.

ExtJs – Grouped Grid Checkbox Column

November 20, 2021 / abhijit

ExtJs Grid has a lot of features built in. Some examples are the Grouped Grid and the Checkbox Selection.

However, grouping these two together poses a bit of a challenge.

After searching on the forums, this post guided me into a nice, working example.

Backup / Restore Postgres, MySQL, SQLite database using Sequel

October 27, 2021 / abhijit

Sequel is a fantastic ORM available in Ruby.

It also comes with an IRB console so it can be run directly from the command line with various options.

For example, to console into an SQLite database testdb.sqlite in the current directory –

$> sequel sqlite://testdb.sqlite

Or for Postgres –

$> sequel postgres://dbuser:dbpassword@localhost/testdb

However, I use sequel most frequently to take quick database backups or to restore them.

ExtJs – Bindable allowBlank

October 23, 2021 / abhijit

ExtJs does have a attribute for required by the allowBlank configuration against fields.

However, this configuration doesn’t have a setAllowBlank or a getAllowBlank method, because of which, it is not possible to bind those fields via the viewModel. So, usually, those fields have to be somehow fetched in the Controller and then that attribute.

This situation can however be remedied very easily.

ExtJs – Monthfield Picker

October 23, 2021 / abhijit

ExtJs, by default, doesn’t provide a month picker.

A monthfield picker allows you to choose specific months only.

The customization that was required, was to have a start date and an end date for those months, so that at the end of the operation, those specific dates could be saved.

Compile fossil on Ubuntu Linux

September 25, 2021 / abhijit

Recently, I had to build fossil from source on Ubuntu because I needed to make a change to the source code.

It required a number of dependencies which is expected to be installed.

They are –
gcc (obviously!)
zlib1g and zlib1g-dev
tcl-dev
tk
libssl
libssl-dev

error while running rake task – “Don’t know how to build task”

September 5, 2021 / abhijit

The default method to pass arguments to Rake tasks is to give the parameters in square brackets –

desc 'Method #1: Use the default rake way to add two numbers and log the result'
task :add, [:num1, :num] do |t, args|
  puts args[:num1].to_i + args[:num].to_i
end

Reference: 4 ways to pass arguments to a Rake task

$ rake add[1,2]
# => 3

However, I would rather pass the arguments like this –

$ rake add 1 2
# => 3

Simplest JavaScript & CSS minifier – YUI Compressor

June 20, 2021 / abhijit

I was looking for a simple JavaScript / CSS minifier. Essentially, a program which will

minify – remove empty lines
obfuscate – shorten variable names

There are many online tools available of course. Of the new ones, Parcel was the best. However, the resulting files had some extraneous code which I could do without.

Then I remembered about YUI Compressor, which I think is one of the first ones introduced many, many years ago.

Ruby Tips 1

June 8, 2021 / abhijit

There are numerous tips in Ruby but I seem to keep forgetting them and having to search for them every time. So high time I started documenting them out.

This one I learnt from 10 Tips & Tricks from Drifting Ruby. I’m only going to keep to Ruby specific ones.