Eno is a Ruby gem for working with SQLite databases in Ruby. Eno provides a set of tools for implementing various persistence and data access patterns using the SQLite embedded database engine.
Features:
- Out of the box support for concurrent database access.
- Automatic connection pooling, with support for thread- and fiber-based concurrency.
- Data stores with specialized APIs for different data access patterns.
- DSL for expressing SQL queries with support for CTEs and window functions.
- Based on [Extralite].
Eno.connect '/path/to/my.db'
# define a query
q = Q {
select :*
from foo
}
# or alternatively
q = Eno.q { select_all; from foo }
# query mutation
Q.from(:foo).select_all
# get all rows
q.to_a
# iterate through records
q.each { |r| ... }
# mutate query
q.where { bar == 42 }.to_a
# count records
q.where { bar == 42 }.count
# which is short for:
q.where { bar == 42 }.select { count(:*) }.single_value
# parametrized queries
q = Q {
select_all
from foo
where bar == _(bar)
}
q.to_a(bar: 42)
class Post < Eno::ModelStore
schema(:post) do
column id: integer, :primary_ke
column user_id: integer
column title: text
column body: text
foreign_key user_id: [:users, :id]
end
end
class User < Eno::ModelStore
schema(:user) do
column id: integer, :primary_key
column name: text
end
one_to_many :posts do
left join post
on post.user_id == user.id
order_by post.id
end
def posts
this = self
Post.where { user_id.in this.select { id } }
end
end
h = User.insert(name: 'foo')
h.class #=> Hash
h[:id] #=> 1
h[:name] #=> 'foo'
u = User[1]
u #=> User <where id = 1>
name = u.values[:name]
u.update(name: 'bar')
posts = u.posts
posts.class #=> Post
posts.each do |r|
puts r.title
puts r.body
end
# checkout a connection explicitly and wrap in a transaction:
Eno.transaction do
Posts.where { user_id == 3 }.update(user_id: nil)
User[3].delete
end
# protection against updating/deleting without a where clause
User.delete
#=> Eno::Error 'To delete all records use the #all modifier, e.g. foo.all.delete'
User.all.delete #=> 1
# custom modifiers
class Post < Eno::ModelStore
...
def by_category(category)
where(category:)
end
def published
where(published: true)
end
end
foo_posts = Post.published.by_category('foo')
foo_posts.where_clause
#=> "where (published is true) and (category = 'foo')"
# Key-value store
cache = Eno::KVStore.new('cache')
cache.set('foo', 'bar')
# set TTL of 30 seconds
cache.setex('foo', 30, 'baz')
# periodic cache eviction
bouncer = Thread.new do
loop do
sleep 10
cache.evict_expired_keys
end
end