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https://github.com/shioyama/wharel
Arel made simple
https://github.com/shioyama/wharel
activerecord arel rails sql
Last synced: 17 days ago
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Arel made simple
- Host: GitHub
- URL: https://github.com/shioyama/wharel
- Owner: shioyama
- License: mit
- Created: 2018-05-25T03:37:45.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2021-10-09T06:55:38.000Z (about 3 years ago)
- Last Synced: 2024-10-14T00:27:08.437Z (about 1 month ago)
- Topics: activerecord, arel, rails, sql
- Language: Ruby
- Homepage: https://dejimata.com/2018/5/30/arel-with-wharel
- Size: 47.9 KB
- Stars: 98
- Watchers: 4
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE.txt
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README
# Wharel
[][gem]
[][actions]
[gem]: https://rubygems.org/gems/wharel
[actions]: https://github.com/shioyama/wharel/actions
Wharel helps you write concise Arel queries with ActiveRecord using Virtual
Rows inspired by
[Sequel](http://sequel.jeremyevans.net/rdoc/files/doc/virtual_rows_rdoc.html).
Although similar in spirit to gems like
[Squeel](https://github.com/activerecord-hackery/squeel) and
[BabySqueel](https://github.com/rzane/baby_squeel), which provide sophisticated
block-based interfaces for querying with Arel, Wharel is much much smaller. In
fact, the core of the gem is only [30 lines
long](https://github.com/shioyama/wharel/blob/master/lib/wharel.rb)! It uses a
single `BasicObject` as a [clean
room](https://www.sethvargo.com/the-cleanroom-pattern/) to evaluate
the query block. That's really all there is to it.
For a more detailed explanation of the implementation, see [this blog
post](https://dejimata.com/2018/5/30/arel-with-wharel).
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'wharel', '~> 1.0.0'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install wharel
## Usage
Suppose we have a model `Post`:
```ruby
class Post < ApplicationRecord
has_many :comments
end
```
And let's assume our `Post` has columns `title` and `content`.
Now, if we wanted to find all the posts with a title which matched the string
"foo" and content which matched the string "bar", we'd have to resort to
something like this:
```ruby
title = Post.arel_table[:title]
content = Post.arel_table[:content]
Post.where(title.matches("foo").and(content.matches("bar")))
```
With Wharel, you can drop the boilerplate and just use a block:
```ruby
Post.where { title.matches("foo").and(content.matches("bar")) }
```
Wharel will map `title` and `content` in the block to the appropriate Arel
attribute for the column.
Wharel also supports most other query methods, e.g. `not`:
```ruby
Post.where.not { title.eq("foo") }
```
... and `order`:
```ruby
Post.order { title.lower }
```
Wharel also supports `select`, `having`, `pluck`, `pick`, `group` and `or` in the same way.
Now suppose we have another model `Comment` with a column `content`, and a
`Post` `has_many :comments`:
```ruby
class Post < ApplicationRecord
has_many :comments
end
class Comment < ApplicationRecord
belongs_to :post
end
```
Now we want to find all comments which match the title of the comment's post.
With standard Arel, you could do this with:
```ruby
posts = Post.arel_table
comments = Comment.arel_table
Comment.joins(:post).where(comments[:content].matches(posts[:title]))
```
Using Wharel, you can pass an argument to blocks to handle this case:
```ruby
Comment.joins(:post).where { |c| Post.where { |p| c.content.matches(p.title) } }
```
Much better!
## Contributing
Notice something wrong or a feature missing? Post an
[issue](https://github.com/shioyama/wharel/issues) or create a [pull
request](https://github.com/shioyama/wharel/pulls).
## License
The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).