rack-cargo gives your API a new /batch route that lets clients perform multiple API calls with a single request.

The batched calls are resolved internally and are then returned as an array of responses:

// This is batch request payload:
{
    "requests": [
        {
            "name": "order",
            "path": "/orders",
            "method": "POST",
            "body": {
                "address": "Home, 12345"
            }
        },
        {
            "name": "order_item",
...

Use Traim to build a RESTful API for your ActiveRecord models with very little code.

Traim assumes your API resources will map 1:1 to your ActiveRecord models and database tables. This assumption usually falls apart after a few months into a project, so be ready to replace your Traim API with something more expressive afterwards.

Traim outputs a Rack application which you can either serve standalone or mount into your Rails app.

Sometimes you add Paperclip image styles, sometimes you remove some. In order to only keep the files you actually need, you should remove stale Paperclip styles from your server.

This script has been used in production successfully. Use at your own risk.

# Config #######################################################################
delete_styles = [:gallery, :thumbnail, :whatever]
scope = YourModel # A scope on the class with #has_attached_file
attachment_name = :image # First argument of #has_attached_file
noop ...

You can configure a Ubuntu system as a gateway in order to share it's internet connection (maybe via WLAN or tethering) with other computers on the network.

On the gateway

• Enable ip traffic forwarding:

  • Open /etc/sysctl.conf

  • Uncomment the line

    net.ipv4.ip_forward=1
    

  • Reload using sudo sysctl -p /etc/sysctl.conf

• Reconfigure ip_tables to allow NAT:
  • Download the attached file
  • Replace online_device with the name of the network device that provides the internet connection
    ...

Rails default config uses the ActiveSupport::Cache::NullStore and disables controller caching for all environments except production:

config.action_controller.perform_caching = false
config.cache_store = :null_store

If you want to test caching you have at least two possibilities:

1. Enable caching for every test (not covered by this card and straightforward)
2. Enable caching for individual test

Enable caching for individual test (file cache)

1. Leave the defau...

These tools help you in checking websites globally:

DNS Checker

This tool allows for global DNS propagation checking.

GeoScreenshot

This tool takes screenshots of a given URL from various locations across the world.

This is useful if, for example, you want to use a background-image that has to scale with the width and the div should only have the height of the picture.

html:

<div class="outer">
  <div class="inner">
  </div>
</div>

css:

.outer {
  width: 100%;
  background-image: image-url('background.png');
  background-size: cover;
}
  
.inner {
  padding-top: 60%;
}

How does it work?

There are several CSS attributes that can handle values as percentage. But they use different other attributes as "reference value...

Typhoeus has a different way of representing array params in a get request than RestClient.

Typhoeus: http://example.com/?foo[0]=1&foo[1]=2&foo[2]=3
RestClient: http://example.com/?foo[]=1&foo[]=2&foo[]=3

Webmock normalizes this url when matching to your stubs, so it is always http://example.com/?foo[]=1&foo[]=2&foo[]=3. This might lead to green tests, but in fact crashes in real world. Rack::Utils.build_nested_query might help to build a get re...

By default Middleman generates files with a .html extension. Because of this all your URLs end in /foo.html instead of /foo, which looks a bit old school.

To get prettier URLs, Middleman lets you activate :directory_indexes in config.rb. This makes a directory for each of your pages and puts a single file index.html into it, e.g. /foo/index.html. This lets you access pages with http://domain/foo.

Don't double your requests!

Unfortunately you are now forcing every br...

Middleman is a static page generator that brings many of the goodies that Rails developers are used to.

Out of the box, Middleman brings Haml, Sass, helpers etc. However, it can be configured to do even better. This card is a list of improvement hints for a Rails developer.

Gemfile

Remove tzinfo-data and wdm unless you're on Windows. Add these gems:

gem 'middleman-livereload'
gem 'middleman-sprockets' # Asset pipeline!

gem 'bootstrap-sass' # If you want to use Bootstrap

gem 'byebug'

gem 'capistrano'
gem 'capistrano-mid...

Sometimes, through some firewall or proxy misconfiguration, you might have to deploy to a server that cannot access the git repository.

Solution 1: HTTP Proxy (this is the preferred fix)

SSH can be tunneled over an HTTP Proxy. For example, when the repo is on github, use this:

1. Install socat

2. Add a ~/.ssh/config on the target server(s) with permission 0600 and this content:

   Host github.com ssh.github.com
     User git
     Hostname ssh.github.com
     Port 443
     ProxyCommand socat - PROXY:<your proxyhost>:%h:%p,...
   

Seven Rules

1. Separate subject from body with a blank line
2. Limit the subject line to 50 characters (max. 72), include reference (unique story ID) to requirements tracker (Linear in our case)
3. Capitalize the subject line
4. Do not end the subject line with a period
5. Use the imperative mood in the subject line
6. Wrap the body at 72 characters
7. Use the body to explain what and why vs. how

5. Use the imperative mood in the subject line (partially extracted)

If applied, this commit will your subject line here

Good:

*...

Database connections are not thread-safe. That's why ActiveRecord uses a separate database connection for each thread.

For instance, the following code uses 3 database connections:

3.times do
  Thread.new do
    User.first # first database access makes a new connection
  end
end

These three connections will remain connected to the database server after the threads terminate. This only affects threads that use ActiveRecord.

You can rely on Rails' various clean-up mechanisms to release connections, as outlined below. This may...

In case you want to require a gem, that is not in the Gemfile of you bundle and therefore not in your loadpath, you need to add the path manually and require the gem afterwards.

Expected error

Requiring a gem, that is not in the Gemfile or .gemspec, will cause an LoadError exception:

require 'example_gem' => LoadError: cannot load such file -- example_gem

Adding a gem to the loadpath temporary

1. You need to install the gem

gem install 'example_gem'

2. Then you need to require the path where the gem was install...

This card compares patterns to store trees in a relation database like MySQL or PostgreSQL. Implementation examples are for the ActiveRecord ORM used with Ruby on Rails, but the techniques can be implemented in any language or framework.

We will be using this example tree (from the acts_as_nested_set docs):

root
|
+-- Child 1
|   |
|   +-- Child 1.1
|   |
|   +-- Child 1.2
|
+-- ...

When you load a dump for development, records may reference images that are not available on your machine.

Requests to those images may end up on your application, e.g. if a catch-all route is defined that leads to a controller doing some heavy lifting. On pages with lots of missing images, this slows down development response times.

You can fix that by defining a Rails route like this:

if Rails.env.development?
  scope format: true, constraints: { format: /jpg|png|gif/ } do
    get '/*anything', to: proc { [404, {}, ['']] }

...

Sometimes you want/have to send specific http(s) requests. You can do that easy with curl or just write the request yourself.

make a http request with nc

nc example.com 80
GET / HTTP/1.1
Host: example.com
# press enter

make a http request with telnet

telnet example.com 80
GET / HTTP/1.1
Host: example.com
# press enter

make https request with openssl

openssl s_client -connect example.com:443
GET / HTTP/1.1
Host: example.com
# press enter

You can specify more headers if you want:

nc example.c...

Barby is a great Ruby gem to generate barcodes of all different sorts.

It includes support for QR codes via rQRCode; if you need to render only QR codes, you may want to use that directly.

Example usage

Generating a barcode is simple:

>> Barby::Code128.new('Hello Universe').to_png
=> "\x89PNG\r\n\u001A..."

Configuration

Barby supports several barcode types and you must require all necessary files explicitly.

For the example a...

This is a visualization of the files that will be generated by some useful rails generators. Invoke a generator from command line via rails generate GENERATOR [args] [options]. List all generators (including rails generators) with rails g -h.

Occasionally, you have to talk to APIs via HTTPS that use a custom certificate or a misconfigured certificate chain (like missing an intermediate certificate).

Using RestClient will then raise RestClient::SSLCertificateNotVerified errors, or when using plain Net::HTTP:

OpenSSL::SSL::SSLError: SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed

Here is how to fix that in your application.

Important: Do not disable certificate checks for production. The interwebs are full of people say...

Using VCR to record communication with remote APIs is a great way to stub requests in tests. However, you may still want to look at the request data like the payload your application sent.

Using WebMock, this is simple: Make your request (which will record/play a VCR cassette), then ask WebMock about it:

expect(WebMock).to have_requested(:post, 'http://example.com').with(body: 'yolo')

Easy peasy.

Related cards

• Faking and testing the network with WebMock

We generally use multiple application servers (at least two) and you have to search on all of them if you don't know which one handled the request you are looking for.

Rails application logs usually live in /var/www/<project-environment-name>/shared/log.
Web server logs usually live in /var/www/<project-environment-name>/log.

Searching through single logs with grep / zgrep

You can use grep in this directory to only search the latest logs or zgrep to also search older (already zipped) logs. zgrep is used just like grep ...