module DBX

Overview

DBX is a helper to handle multi DBs using the compatible drivers with the common crystal-db module.

Example with PostgreSQL:

# Connection URI / DSL https://www.postgresql.org/docs/current/libpq-connect.html#h5o-9
db = DBX.open("app", "postgres://...", true)

pp DBX.db?("app") ? "defined" : "not defined"

db.query "select id, created_at, email from users" do |rs|
  rs.each do
    id = rs.read(Int32)
    created_at = rs.read(Time)
    email = rs.read(String)
    puts "##{id}: #{email} #{created_at}"
  end
end

# Closes all connections of this DB connection pool and remove this DB connection pool.
DBX.destroy("app")

Model:

class User
  include DBX::ORM::DSL

  field lang : String

  @[JSON::Field(key: "firstName")]
  field first_name : String?
end

db = DBX.open "app", App.cfg.db_uri

user = User.from_rs(db.query("SELECT id, lang, first_name FROM users"))
pp user.to_json

user = User.from_json "{\"lang\":\"fr\",\"firstName\":\"Nico\"}"
pp user

See also DBX::ORM for a more advanced model system and query builder.

Resources:

• https://crystal-lang.github.io/crystal-db/api/index.html
• https://github.com/Nicolab/crystal-dbx/tree/master/guide

Defined in:

Constant Summary

VERSION = {{ (`shards version \"/srv/crystaldoc.info/github-Nicolab-crystal-dbx-v1.1.1/src\"`).chomp.stringify.downcase }}

Class Method Summary

• .db(name : String, uri : String, strict = false) : DB::Database

  Same as .open.

• .db(name : String) : DB::Database

  Uses a given DB connection pool.

• .db?(name : String) : Bool

  Checks that a DB connection pool exists.

• .dbs : DBHashType

  Returns all DB::Database instances.

• .destroy(name : String)

  Closes all connections of the DB connection pool name and remove the name DB connection pool.

• .destroy : Tuple(Int32, Int32)

  Destroy all DB connection pool and and their connections.

• .open(name : String, uri : String, strict = false) : DB::Database

  Ensures only once DB connection pool by name is open.

• .pool_open_connections(name : String) : Int32

  Gets the number of the connections opened in the pool of name.

• .pool_stats(name : String) : DB::Pool::Stats | Nil

  Pool stats https://crystal-lang.github.io/crystal-db/api/latest/DB/Pool.html

Macro Summary

• around_query_or_exec(&block)

  This macro allows injecting code to be run before and after the execution of the request.

Class Method Detail

Macro Detail

DBX.around_query_or_exec do |args|
  puts "before"
  res = yield
  puts "after"

  puts res.class
  puts "exec" if res.is_a?(DB::ExecResult)
  puts "query" if res.is_a?(DB::ResultSet)

  puts "with args:"
  pp args

  res
end

DBX.around_query_or_exec do |args|
  start = Time.monotonic
  res = yield
  elapsed_time = Time.monotonic - start

  puts "Query execution time: #{elapsed_time}"
  res
end