Rails partials have a lot of "hidden" features and this card describes some non-obvious usages of Rails Partials.
The most basic way to render a partial:
render partial: 'partial'
This will render a _partial.html.erb file. Notice how all partials need to be prefixed with _.
It's possible to define local variables that are only defined in the partial template.
# _weather.html.erb
<h1>The weather is <%= condition %></h1>
# index.html.erb
render partial: 'weather', locals: { condition: ...
If you use a newer SSH key generated with the ED25519 algorithm instead of RSA (see Create a new SSH key pair), the deployment with Capistrano may fail with the following message:
The deploy has failed with an error: unsupported key type `ssh-ed25519'
net-ssh requires the following gems for ed25519 support:
* ed25519 (>= 1.2, < 2.0)
* bcrypt_pbkdf (>= 1.0, < 2.0)
See https://github.com/net-ssh/net-ssh/issues/565 for more information
Gem::LoadError : "ed25519 i...
This is an story checklist I use to work on stories. For this purpose I extracted several cards related to the makandra process and ported them into a check list and refined that over time a little bit.
This task list is divded by the Gate keeping process in the following steps:
1. Starting a new feature
2. Working on the story
3. Finishing a feature
4. After Review
Here are ...
If you are on a Linux shell and want to open a file with whatever default application is configured for that type, this often works:
xdg-open Quote.odt
xdg-open invoice.pdf
xdg-open index.html
Make an alias so you have a simpler API (like Mac OS): alias open=xdg-open or alias x=xdg-open.
You can choose your "Default applications" via UI in the Ubuntu "Settings" application (gnome-control-center). This is just a very rough setting (e.g. open Photos with Shotwell Viewer).
If a certain file...
Sass comes with many built-in functions to manipulate color. Some of the more interesting functions include:
adjust-hue($color, $degrees)
Changes the hue of a color.
lighten($color, $amount)
Makes a color lighter.
darken($color, $amount)
Makes a color darker.
saturate($color, $amount)
Makes a color more saturated.
desaturate($color, $amount)
Makes a color less saturated.
grayscale($color)
Converts a color to grayscale.
complement($color)
Returns the compleme...
Here is a Javascript function reloadUsers() that fetches a HTML snippet from the server using AJAX and replaces the current .users container in the DOM:
window.reloadUsers = ->
$.get('/users').then (html) ->
$('.users').html(html)
Testing this simple function poses a number of challenges:
<div class="users">...</div> container in the current DOM. Obviously the Jasmine spec runner has no such container./users and we want to prevent network interaction in our uni...In the past we validate and set default values for boolean attributes in Rails and not the database itself.
Reasons for this:
An alternative approach, which currently reflects more the general opinion of the Rails upstream on constraints in the database, is adding default values in the schema of the database itself. We also ...
HTTP header values must only contain low-ASCII (7-bit) characters for safe transport. From RFC 7230:
Historically, HTTP has allowed field content with text in the ISO-8859-1 charset [ISO-8859-1], supporting other charsets only through use of [RFC2047] encoding. In practice, most HTTP header field values use only a subset of the US-ASCII charset [USASCII]. Newly defined header fields SHOULD limit their field values to US-ASCII octets.
If you need to transport 8-bit+ characters (e.g...
When installing gems, a lot of time is spent building locally installed documentation that you probably never use.
We recommend you disable documentation generation for gem install by default.
Note that Bundler won't install documentation, so this advice applies only when installing gems manually.
If you don't already have it, create a ~/.gemrc file. The gemrc is a Yaml file, so add the following line to add default switches to the gem command.
gem: --no-document
(If you do n...
#size in most cases.
#size and #count. See below.COUNT(*) query if a counter cache is not set up.#count will return that cached value instead of executing a new query.RubyMine has a HTTP Client that can be useful to test web APIs.
Just create a .http scratch file an write your request in it.
The request can then be executed with the "Run all requests in File" button above the file.
Some alternatives:
The format for request is like this:
Method Request-URI HTTP-Version
Header-field: Heade...
Not all email clients support external images in all situations, e.g. an image within a link. In some cases, a viable workaround is to turn your images into inline attachments.
Note
Rails provides a simple mechanism to achieve this:
This documentation makes it look like you have to care about these attachments in two places. You have to create the attachment in t...
Carrierwave's BaseUploader can have some validations that you can use by overriding a certain method, which's expected name is hard coded. A popular example is extension_allowlist, which returns an array of strings and let's you only upload files that have a filename with an extension that matches an entry in that array. Another useful validation can be size_range, which gives you a little bit of control over how your storage gets polluted.
This is often good enough, but some times you need to validate special cases.
Since Rails 7 you are able to encrypt database information with Active Record. Using Active Record Encryption will store an attribute as string in the database. And uses JSON for serializing the encrypted attribute.
Example:
p: Payloadh: Headersiv: Initialization Vectorat: Authentication Tag{ "p": "n7J0/ol+a7DRMeaE", "h": { "iv": "DXZMDWUKfp3bg/Yu", "at": "X1/YjMHbHD4talgF9dt61A=="} }
Note this before encrypting attributes with Active Record:
...
Just run git show branch:file. Examples:
git show HEAD~:bin/command
git show origin/master:../lib/version.rb
For outputting a given String in HTML, you mostly want to replace line breaks with <br> or <p> tags.
You can use simple_format, but it has side effects like keeping some HTML.
If you only care about line breaks, you might be better off using a small, specialized helper method:
def format_linebreaks(text)
safe_text = h(text)
paragraphs = split_paragraphs(safe_text).map(&:html_safe)
html = ''.html_safe
paragraphs.each do |paragraph|
html << content_tag(:p, paragraph)
end
html
end
Full di...
Sometimes I ran across a GitHub merge request of a gem where it was not completely obvious in which version the change was released. This might be the case for a bugfix PR that you want to add to your project.
Git can help you to find the next git tag that was set in the branch. This usually has the name of the version in it (as the rake release task automatically creates a git tag during release).
git name-rev --tags <commit ref>
Note
The more commonly used
git describecommand will return the last tag before a c...
In Rails 5+ you can access a helper from a controller using the helpers method:
# Inside a controller action
helpers.link_to 'Foo', foo_path
In older Rails versions you can use view_context instead:
# Inside a controller action
view_context.link_to 'Foo', foo_path
When you eagerly load an association list using the .include option, and at the same time have a .where on an included table, two things happen:
where condition, even though you only wanted to use the where condition to filter the containing model.The second case's behavior is mostly unexpected, because pre-loaded associations usually don't care about the circumstances under whi...
We can use ActiveRecord's where to add conditions to a relation. But sometimes our condition is not on the model itself, but on an associated model. This card explains multiple ways to express this condition using ActiveRecord's query interface (without writing SQL).
As an example we will use a User that has many Posts:
class User < ApplicationRecord
has_many :posts
scope :active, -> { tra...
When you need test images, instead of using services like lorempixel or placehold.it you may generate test images yourself.
Here we build a simple SVG image and wrap it into a data: URI. All browsers support SVG, and you can easily adjust it yourself.
Simply set it as an image's src attribute.
Simple solution in modern JavaScript, e.g. for use in the client's browser:
function svgUri(text) {
let svg = `
<svg width="320" height="240" xmlns="http://www.w3...
There is a kind of features in web applications that hinder automated integration tests. Examples include cookie consent banners or form captchas. Clearly, these should be disabled so you do not have to explicitly deal with them in each and every test (like, every test starting with accepting the cookies notice). On the other hand, they must be tested as well.
A good feature disabling solution should therefore meet these requirements:
The feature is generally disabled in tests. A test does not need to do anything manually.
It is *...
return to return from a method. return accepts a value that will be the return value of the method call.break to quit from a block and from the method that yielded to the block. break accepts a value that supplies the result of the expression it is “breaking” out of.next to skip the rest of the current iteration. next accepts an argument that will be the result of that block iteration.The following method will serve as an example in the details below:
def example
puts yield
puts ...
There are three ways to define your own RSpec matchers, with increasing complexibility and options:
RSpec::Matchers.define :be_a_multiple_of do |expected|
match do |actual|
actual % expected == 0
end
# optional
failure_message do |actual|
"expected that #{actual} would be a multiple of #{expected}"
end
# optional
failure_message_when_negated do |actual|
"expected that #{actual} would not be a multiple of #{expected}"
end
end