From d24723ec59b2ceae6fd42f62746330841c35e058 Mon Sep 17 00:00:00 2001 From: Sam Partington Date: Tue, 25 Oct 2022 14:33:09 +0100 Subject: [PATCH] Add Rails recommendations to styleguide These were originally in our web-systems documentation --- STYLEGUIDE.md | 128 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 128 insertions(+) diff --git a/STYLEGUIDE.md b/STYLEGUIDE.md index 1e55a3be..56839237 100644 --- a/STYLEGUIDE.md +++ b/STYLEGUIDE.md @@ -27,6 +27,9 @@ This is GitHub's Ruby Style Guide, inspired by [RuboCop's guide][rubocop-guide]. 1. [Conditional keywords](#conditional-keywords) 2. [Ternary operator](#ternary-operator) 17. [Syntax](#syntax) +18. [Rails](#rails) + 1. [content_for](#content_for) + 2. [Instance Variables in Views](#instance-variables-in-views) ## Layout @@ -893,4 +896,129 @@ result = hash.map { |_, v| v + 1 } Refactoring is even better. It's worth looking hard at any code that explicitly checks types. +## Rails + +### content_for + +Limit usage of `content_for` helper. The use of `content_for` is the same as setting an instance variable plus `capture`. + +``` erb +<% content_for :foo do %> + Hello +<% end %> +``` + +Is effectively the same as + +``` erb +<% @foo_content = capture do %> + Hello +<% end %> +``` + +See "Instance Variables in Views" below. + +#### Common Anti-patterns + +**Using `content_for` within the same template to capture data.** + +Instead, just use `capture`. + +``` erb + +<% content_for :page do %> + Hello +<% end %> +<% if foo? %> +

+ <%= yield :page %> +

+<% else %> + <%= yield :page %> +<% end %> +``` + +Simply capture and use a local variable since the result is only needed in this template. + +``` erb + +<% page = capture do %> + Hello +<% end %> +<% if foo? %> +

+ <%= page %> +

+<% else %> + <%= page %> +<% end %> +``` + +**Using `content_for` to pass content to a subtemplate.** + +Instead, `render layout:` with a block. + +``` erb + +<% content_for :page do %> + Hello +<% end %> +<%= render partial: "page" %> + +

+ <%= yield :page %> +

+``` + +Pass the content in a block directly to the `render` function. + +``` erb + +<%= render layout: "page" do %> + Hello +<% end %> + +

+ <%= yield %> +

+``` + +### Instance Variables in Views + +In general, passing data between templates with instance variables is discouraged. This even applies from controllers to templates, not just between partials. + +`:locals` can be used to pass data from a controller just like partials. + +``` ruby +def show + render "blob/show", locals: { + :repository => current_repository, + :commit => current_commit, + :blob => current_blob + } +end +``` + +Rails implicit renders are also discouraged. + +Always explicitly render templates with a full directory path. This makes template callers easier to trace. You can find all the callers of `"app/view/site/hompage.html.erb"` with a simple project search for `"site/homepage"`. + +``` ruby +def homepage + render "site/homepage" +end +``` + +#### Exceptions + +There are some known edge cases where you might be forced to use instance variables. In these cases, its okay to do so. + +##### Legacy templates + +If you need to call a subview that expects an instance variable be set. If possible consider refactoring the subview to accept a local instead. + +##### Layouts + +Unfortunately the only way to get data into a layout template is with instance variables. You can't explicitly pass locals to them. + [rubocop-guide]: https://github.com/rubocop-hq/ruby-style-guide pFad - Phonifier reborn

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