Tren lets you use your SQL as a first class method in your Crystal code.

Installation

Add this to your application's shard.yml:

dependencies:
  tren:
    github: sdogruyol/tren

Usage

Create a simple SQL file. The first line must be -- name: your_method_name(args).

-- name: get_users(name : String, surname : String)

SELECT * FROM users WHERE name = '{{ name }}' AND surname = '{{ surname }}'

Require Tren and load your SQL file. It's going to create a first class method to your SQL.

require "tren"

Tren.load("/path/to/your/file.sql")

# Or you can load multiple files at once:
Tren.load("./db/**/*.sql")

Overloading

-- name: get_users(name : String, surname : String)

SELECT * FROM users WHERE name = '{{ name }}' AND surname = '{{ surname }}'

-- name: get_users(name : String, age : Int32)

SELECT * FROM users WHERE name = '{{ name }}' AND age = {{ age }}

Meaningful Compiler Errors

Since Tren is creating native Crystal methods, you can see meaningful errors on compile process.

in ./your/file: no overload matches 'get_users' with types String, Bool
Overloads are:
 - get_users(name : String, surname : String)
 - get_users(name : String, age : Int32)

    get_users("john", true)

Prevent SQL Injections

SQL statements are escaped by default. But you are able to make injectable (raw) parameters by writing ! to the parameter.

-- name: get_users(name : String, surname : String)

SELECT * FROM users WHERE name = '{{! name }}' AND surname = '{{! surname }}'

Composing SQLs

You can compose Tren methods easily to be DRY.

-- name: filter_user(name : String, surname : String)

WHERE name = '{{ name }}' AND surname = '{{ surname }}'

Let's reuse this now:

-- name: get_users(name : String, surname : String)

SELECT * FROM users {{! filter_user(name, surname) }}

Escape Character

For example PostgreSQL uses '' for escaping string. To set your escape character for postgresql.

Tren.escape_character = "\\'"

Contributing

1. Fork it ( https://github.com/sdogruyol/tren/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• f Fatih Kadir Akın - creator, maintainer
• sdogruyol Serdar Doğruyol - creator, maintainer

Built on a TREN from Ankara to Istanbul.