Validate Active Model Numbers Greater Than and Less Than

If you have a model and you want to do validation related to numerical values, such as validate a certain number is less than or greater than another, here’s how you can do it.

validates :inventory_qty, :numericality => { greater_than_or_equal_to: 0, less_than: 100 }

Checkout the documentation for more details.

Credit here.


Use jQuery to Animate Background Color

Although CSS keyframes is probably the easiest way to animate the background color of an element on the page, since earlier versions of Internet Explorer (IE < 10) don’t support CSS keyframes, if you need a more widely supported solution, you can do the same thing in jQuery.

To do this, you use the jQuery .animate() function.  The catch is that in order to be able to change colors with this function, you also need to include the jQuery Color plugin.

The way I did this in Rails was to just create a new file under assets/javascripts and called it jquery_color.js. Then copied the code from the plugin into that file.

Ok, now for the actual code. Credit for this goes to StackOverflow user fitorec‘s answer to this question, and this jsfiddle that he wrote.

$(document).ready(function() {
  var animate_loop, colors, i;
  colors = ['#FFB30C', '#58EC00', '#0087EC', '#EEEEEE', '#FF5A00'];
  i = 0;
  animate_loop = function() {
      backgroundColor: colors[i++ % colors.length]
    }, 1500, function() {

This creates a colors array with the colors that you want to animate. Then it calls the .animate() function, passing in the backgroundColor property, and assigning it to one of the colors in the colors array, and iterates i to go through the array. The animate_loop function then calls itself, to create an infinite loop.

Of course if using Rails you can use js2coffee to convert to coffeescript.

Rails Form form_for Objects Reverse Order of Array

This is pretty simple, but I couldn’t figure out how to do it.  Basically I had a view that went through each object in the nested table array, and rendered it.  However, instead of rendering them all in the order they were created from top to bottom on the page, I wanted to render them in reverse order, so the most recent one was at the top of the page.  There might be several ways of doing this, but here is how I finally did it, and its pretty simple. (probably shouldn’t have taken me this long to figure it out, but hopefully you can read this and save some time!)

Here is the original code in the view:

<%= simple_form_for(@lot) do |f| %>
  <strong>Lot Number:</strong> <%= @lot.number %>
  <strong>Item</strong> <%= Item.find(@lot.item_id).number_rev_name %>
  <strong>Inventory Quantity:</strong> <%= @lot.inventory_qty %>

  <-- Here is where I render a partial for each build_lot, which is a 
         has_many, :through join_table -->
  <%= f.simple_fields_for :build_lots,  do |build_lot| %>
    <%= render 'build_lot_fields', :f => build_lot %>
  <% end %>
  <%= f.button :submit, class: 'btn btn-primary' %>
<% end %>

And here is the code from the partial for each build_lot, _build_lot_fields.html.erb

<div class='nested-fields build-lot-fields'>
  <div class='well'>
    <%= f.input :my_build_id, collection: MyBuild.order(:start_date), label_method: :description, value_method: :id, :prompt => 'Choose a Build', selected: MyBuild.where(current: true), input_html: { id: 'build_select'} %>
    <%= f.input :pull_quantity, label: 'Pull Quantity', as: :string %>
    <%= f.label 'Date' %><%= %><br>
    <%= f.input :employee_id, collection: Employee.order(:first_name), label_method: :first_name, value_method: :id, prompt: "Choose your name" %>

So this simple trick to reverse the order of the build_lots array that is iterated through to render each partial, is to simply add another parameter to the fields_for call (in this case simple_fields_for from the simple_form gem). This second parameter that we add will be the build_lots array reversed. You can find more about the usage of the fields_for method on its documentation page.

But first we need to create this reversed array in the controller. So in the controller (in the function for the view where I want to show the reversed build_lots) I added this line:

@reverseBuildLots = @lot.build_lots.reverse

Then back in the view, I simply change the form_for line like this:

<%= f.simple_fields_for :build_lots, @reverseBuildLots do |build_lot| %>

passing in the @reverseBuildLots parameter, which is an array of build_lots in reverse order that we created in the controller.

Pretty simple, but took me a while to figure out. Hopefully this will save you some time!

credit here