Orma

Orma is an ActiveRecord-style persistence layer for Crystal with built-in continuous migration. It aims to keep record definitions, querying, associations, and schema evolution close together so you can move quickly without maintaining a separate migration workflow for every change.

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     orma:
       github: sbsoftware/orma
   

2. Run shards install

Usage

require "orma"

# ENV["DATABASE_URL"] must be set

class Post < Orma::Record
  column title : String

  has_many_of Comment
end

class Comment < Orma::Record
  column body : String

  belongs_to Post
end

post = Post.create(title: "Hello")
Comment.create(body: "Nice post", post_id: post.id)

comments = Comment.where(post_id: post.id)
comment = comments.first
comment.post.title # => "Hello"

Why Orma

• Define records with columns directly in Crystal
• Query records with a compact, chainable API
• Model relationships with belongs_to and has_many
• Keep schema changes in sync through continuous migration
• Work against supported database backends without centering the API around one specific adapter

Core Concepts

Records and columns

Define your model as a Crystal class inheriting from Orma::Record. Columns are declared in the class body, and Orma uses those declarations as the source of truth for persistence and schema management.

Query chaining

Records can be queried through a chainable API for filtering, ordering, and limiting result sets, giving you an ActiveRecord-like workflow while staying close to Crystal types.

Associations

Orma supports common record relationships such as belongs_to and has_many, so related records can be modeled directly in your domain classes.

Continuous migration

Continuous migration is an experimental, yet central feature of Orma.

Instead of maintaining a separate migration file for each schema change, Orma can derive and apply structural changes from your record definitions.

Column removal is designed as a staged process. If you want to retire a column, change it from column to deprecated_column. Continuous migration will rename the backing column to _<name>_deprecated while keeping the value readable through the model.

After the deprecated column is no longer needed, remove the deprecated_column declaration from the model. On the next migration run, Orma will delete the matching _<name>_deprecated column. Note that simply removing non-deprecated column definitions will leave them in the database as-is.

This is currently the built-in path for schema evolution and should be treated with appropriate care, especially in production environments. To enable it, set ENV["ORMA_CONTINUOUS_MIGRATION"]=1. Opting out of it means you'll have to take care of migrations yourself.

Supported Databases

Orma currently supports:

• SQLite3
• PostgreSQL

Development

Run the test suite:

crystal spec

Contributing

1. Fork it (https://github.com/sbsoftware/orma/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

• Stefan Bilharz - creator and maintainer