Common db api for crystal. You will need to have a specific driver to access a database.
If you are creating a shard that will work with any driver, then add crystal-db
as a dependency in shard.yml
:
dependencies:
db:
github: crystal-lang/crystal-db
If you are creating an application that will work with some specific driver(s), then add them in shard.yml
:
dependencies:
sqlite3:
github: crystal-lang/crystal-sqlite3
crystal-db
itself will be a nested dependency if drivers are included.
Note: Multiple drivers can be included in the same application.
This shard only provides an abstract database API. In order to use it, a specific driver for the intended database has to be required as well:
The following example uses SQLite where ?
indicates the arguments. If PostgreSQL is used $1
, $2
, etc. should be used. crystal-db
does not interpret the statements.
require "db"
require "sqlite3"
DB.open "sqlite3:./file.db" do |db|
# When using the pg driver, use $1, $2, etc. instead of ?
db.exec "create table contacts (name text, age integer)"
db.exec "insert into contacts values (?, ?)", "John Doe", 30
args = [] of DB::Any
args << "Sarah"
args << 33
db.exec "insert into contacts values (?, ?)", args: args
puts "max age:"
puts db.scalar "select max(age) from contacts" # => 33
puts "contacts:"
db.query "select name, age from contacts order by age desc" do |rs|
puts "#{rs.column_name(0)} (#{rs.column_name(1)})"
# => name (age)
rs.each do
puts "#{rs.read(String)} (#{rs.read(Int32)})"
# => Sarah (33)
# => John Doe (30)
end
end
end
Issues not yet addressed:
- Support non prepared statements. #25
- Time data type. (implementation details depends on actual drivers)
- Data type extensibility. Allow each driver to extend the data types allowed.
- Transactions & nested transactions. #27
- Connection pool.
- Logging
- Direct access to
IO
to avoid memory allocation for blobs.
- Fork it ( https://github.com/crystal-lang/crystal-db/fork )
- Create your feature branch (git checkout -b my-new-feature)
- Commit your changes (git commit -am 'Add some feature')
- Push to the branch (git push origin my-new-feature)
- Create a new Pull Request
- bcardiff Brian J. Cardiff - creator, maintainer