Dillon Hafer

Check if a form is valid

2023-01-13T00:00:00+00:00

You can check if a form passes HTML validations with javascript using the checkValidity function:

<form name="login">
 <fieldset>
   <legend>Email</legend>
   <input type="email" name="email" required />
 </fieldset>

 <fieldset>
   <legend>Password</legend>
   <input type="password" name="password" required />
 </fieldset>

 <div style="margin-top: 1rem">
   <input type="submit" value="login" />
   <button type="button" id="validate">
    validate
   </button>
 </div>
</form>

<script>
  const button = document.querySelector("#validate")
  if (button) {
    button.addEventListener("click", function() {
      alert(document.forms.login.checkValidity() ? "Form is valid" : "INVALID");
    });
  }
</script>

Sort array of numbers

2023-01-01T00:00:00+00:00

In javascript, the Array sort function will cast everything to a string. So when you have an array of numbers, you need to repetitively cast them to numbers:

[1080, 720, 480].sort()
=> [1080, 480, 720]

So you need have to write your own sort function (don’t mess it up!)

[1080, 720, 480].sort((a, b) => Number(a) - Number(b))
=> [480, 720, 1080]

🐉

ActiveStorage direct upload subfolders

2022-11-12T00:00:00+00:00

When using S3, Rails does not let you configure subfolders for active storage. Every attachment lives at the root of your bucket.

This is not recommended, but cannot be helped

The only way to store attachments into subfolders is to monkey patch the direct uploads controller:

# config/initializer/direct_uploads_monkey_path.rb
Rails.application.config.to_prepare do
  class ActiveStorage::DirectUploadsController < ActiveStorage::BaseController
    def create
      key = "#{sub_dir}/#{user.id}/#{ActiveStorage::Blob.generate_unique_secure_token}"
      upload_attrs = {key:}.merge(blob_args)
      blob = ActiveStorage::Blob.create_before_direct_upload!(**upload_attrs)
      render json: direct_upload_json(blob)
    end

    private

    def user
      @user ||= User.enabled.find(session[:current_user_id])
    end

    def sub_dir
      if /cool-uploads/.match?(request.referer)
        "cool-uploads"
      elsif /company-settings/.match?(request.referer)
        "companies"
      else
        "uploads"
      end
    end
  end
end

Test values of an array

2022-10-22T00:00:00+00:00

Javascript arrays have a function called some that can be used to determine if at least one element of an array passes a test:

console.log(["1", "2", "3"].some(n => n === 1))
=> false

How to add hidden fields to button_to

2022-10-21T00:00:00+00:00

The button_to helper take a params key to add hidden fields to the form it renders:

<%= button_to "Delete", users_path, method: :delete, params: {send_email: false} %>

Produces:

<form class="button_to" method="post" action="/users">
<input type="hidden" name="_method" value="delete" autocomplete="off">
<button type="submit">Delete</button>
<input type="hidden" name="authenticity_token" value="8nOHRzvQIev3XHW6YrEJUIohVGLm0PKOPNly8ovPdDtF75eyBj5Rvz_1FzDmVybbJ3YyfC7YExtfRQC3_H5NNw" autocomplete="off">
<input type="hidden" name="send_email" value="false" autocomplete="off">
</form>

Fill in hidden fields with Capybara

2022-10-20T00:00:00+00:00

Normally you are not able to interact with hidden fields, but you can still change the value with #set:

find("input[type=hidden]", visible: false).set("my cool value")

Access Exclusive locks block select statements

2022-10-19T00:00:00+00:00

The alter table, vacuum full, reindex, and refresh materialized view statements are a few examples that may take out an ACCESS EXCLUSIVE lock by default. This means that select statements are blocked until one of these statements has finished.

Add custom flash keys

2022-10-05T00:00:00+00:00

ActionController::Base has a default flash types of [:notice] allowing you to pass a key to #redirect_to:

class Controller < ActionController::Base
  def create
    if true
      redirect_to root_path, status: :see_other, notice: "Created"
    else
      flash[:error] = "Could not create"
      redirect_to root_path, status: :see_other
    end
  end

However, you can add :error as a custom type to get the convenience argument:

class Controller < ActionController::Base
  add_flash_types :error

  def create
    if true
      redirect_to root_path, status: :see_other, notice: "Created"
    else
      redirect_to root_path, status: :see_other, error: "Could not create"
    end
  end

Enforce TLS… except for health checks

2022-10-03T00:00:00+00:00

Many infrastructure stability platforms will need to check the health of a rails application directly, not through a load balancer. Because many applications don’t terminate TLS directly (because it’s delegated to the load balancer) a health check endpoint must adhere the the force_ssl = true config option, but without TLS, causing a failure.

Rails 7 has an option to work around this (config.ssl_options):

# config/environments/production.rb
# Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
config.force_ssl = true
config.ssl_options = {
  redirect: {exclude: ->(request) { /healthz/.match?(request.path) }}
}

Clone a specific git branch

2022-08-31T00:00:00+00:00

After cloning a repo, git will set your branch to whatever the value of HEAD is in the source repo:

$ ssh git@example.com
$ cat my-repo.git/HEAD
ref: refs/heads/master

If there is a different branch you want to clone, use the --branch flag:

$ git clone --branch my-feature git@example.com/my-repo.git
$ git branch
* my-feature