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README
Jennifer
ActiveRecord pattern implementation for Crystal with a powerful query DSL, validation, relationship definition, translation and migration mechanism.
Installation
Add this to your application's shard.yml
:
dependencies:
jennifer:
github: imdrasil/jennifer.cr
version: "~> 0.12.0"
Requirements
- you need to choose one of the existing drivers for your DB: mysql or postgres; sqlite3 adapter automatically installs required driver for it;
- crystal
>= 1.0.0
.
Usage
Jennifer allows you to maintain everything for your models - from DB migrations and field mapping to callbacks and building queries. For detailed information see the docs and API documentation.
CLI
For command management Jennifer uses Sam. Due to this you can easily create/migrate/drop database or invoke generator to bootstrap your models and migrations.
Migration
Jennifer has built-in database migration management system. Migrations allow you to organize all database changes.
To start using Jennifer you'll first need to generate a migration:
$ crystal sam.cr -- generate:migration CreateContact
then fill the created migration file with content:
class CreateContact < Jennifer::Migration::Base
def up
# Postgres requires to create specific enum type
create_enum(:gender_enum, ["male", "female"])
create_table(:contacts) do |t|
t.string :name, {:size => 30}
t.integer :age
t.integer :tags, {:array => true}
t.field :gender, :gender_enum
t.timestamps
end
end
def down
drop_table :contacts
drop_enum(:gender_enum)
end
end
and run
$ crystal sam.cr -- db:setup
to create the database and run the newly created migration.
Model
Jennifer provides next features:
- flexible model schema definition
- relationship definition (
belongs_to
,has_many
,has_one
,has_and_belongs_to_many
) - including polymorphic ones - built-in extendable validations
- model-specific query scope definition
- callbacks
- database view support
- SQL translations
Hers is a model example:
class Contact < Jennifer::Model::Base
with_timestamps
mapping(
id: Primary64, # is an alias for Int64? primary key
name: String,
gender: { type: String?, default: "male" },
age: { type: Int32, default: 10 },
description: String?,
created_at: Time?,
updated_at: Time?
)
has_many :facebook_profiles, FacebookProfile
has_and_belongs_to_many :countries, Country
has_and_belongs_to_many :facebook_many_profiles, FacebookProfile, join_foreign: :profile_id
has_one :passport, Passport
validates_inclusion :age, 13..75
validates_length :name, minimum: 1, maximum: 15
validates_with_method :name_check
scope :older { |age| where { _age >= age } }
scope :ordered { order(name: :asc) }
def name_check
return unless description && description.not_nil!.size > 10
errors.add(:description, "Too large description")
end
end
Query DSL
Jennifer allows you to query the DB using a flexible DSL:
Contact
.all
.left_join(Passport) { _contact_id == _contact__id }
.order(id: :asc).order(Contact._name.asc.nulls_last)
.with_relation(:passport)
.to_a
Contact.all.eager_load(:countries).where { __countries { _name.like("%tan%") } }
Contact.all.group(:gender).group_avg(:age, PG::Numeric)
Supported features:
- fetching model objects from the database
- fetching records from a specific table
- magic underscore table column notation which allows effectively reference any table column or alias
- eager loading of model associations any levels deep
- support of common SQL functions (including aggregations) and mechanism to register own ones
- flexible DSL of all SQL clauses (
SELECT
,FROM
,WHERE
,JOIN
,GROUP BY
, etc.) CTE
supportJSON
operators- table and column aliasing
Much more about the query DSL can be found in the wiki [page](./docs/query_dsl.md).
Internationalization
You can easily configure error message generated for certain validation violation for a specific model or globally. Model and attribute names can be easily configured as well. For internationalization purpose i18n is used. For more details how does it work see [wiki](./docs/internationalization_dsl.md).
Logging & Debugging
Jennifer uses a standard Crystal logging mechanism so you could specify your own logger, backend and formatter:
# This is the default logger configuration
Jennifer::Config.configure do |conf|
conf.logger = Log.for("db", :debug)
end
Log.setup "db", :debug, Log::IOBackend.new(formatter: Jennifer::Adapter::DBFormatter)
Jennifer::Model::Base#inspect
returns formatted information about model attributes filtering out all unnecessary information.
Address.first!.inspect
# #<Address:0x7efde96ac0d0 id: 1, street: "Ant st. 69", contact_id: nil, created_at: 2019-06-10 11:11:11.665032000 +03:00 Local>
Also, you can get a query execution plan explanation right from your code - just execute #explain
on query to get appropriate information (output is database specific):
Contact.all.explain # => Seq Scan on contacts (cost=0.00..14.30 rows=100.0 width=320)
Testing tips
The fastest way to rollback all changes in the DB after test case is by using a transaction. So add:
Spec.before_each do
Jennifer::Adapter.default_adapter.begin_transaction
end
Spec.after_each do
Jennifer::Adapter.default_adapter.rollback_transaction
end
to your spec_helper.cr
. NB. you could simply use regular deleting or truncation, but a transaction will provide a 15x speed up (at least for postgres; mysql gets less impact).
These functions can be safely used only under test environment.
Versioning
Now that Jennifer is under heavy development, there could be many breaking changes. So please check the release notes to check if any of the changes may prevent you from using it. Also, until this library reaches a beta version, the next version rules will be followed:
all bug fixes, new minor features or (sometimes) ones that don't break the existing API will be added as a patch number (e.g. 0.3.4);
all breaking changes and new important features (as well as reaching a milestone) will be added by bumping the minor digit (0.4.0);
So even a patch version change could bring a lot of new stuff.
If there is a branch for the next release - it will be removed 1 month after the release. So please use them only as a hotfix or for experiments or contribution.
Development
Before developing any feature please create an issue where you describe your idea.
To setup dev environment run ./scripts/setup.sh
- it creates ./scripts/database.yml
configuration file. You can override there any values specific to your environment (like DB user & password).
To create the databases:
# Postgres
$ make sam db:setup
# Mysql
$ DB=mysql make sam db:setup
Running tests
All unit tests are written using core spec
. Also in spec/spec_helper.cr
some custom unit test matchers are defined. All migrations are under the ./scripts/migrations
directory.
The common way to run tests is just use using regular crystal spec tool:
$ crystal spec
By default postgres
adapter is used. To run tests against mysql
add DB=mysql
before command. Also custom database user and password could be specified:
In case you need to set the database user or password, use:
$ DB_USER=user DB_PASSWORD=pass crystal spec
Testing multiadapter support
To run tests with multiple adapter involved you should create and migrate database with PAIR=1
environment variable defined. For testing purpose mysql
adapter will be created when postgres
one is used as a main one and vice verse. Therefore both databases should be available to receive connections.
Also PAIR
variable should be defined when running tests.
Integration tests
Except unit tests there are also several integration tests. These tests checks opportunity to compile and invoke Jennifer functionality in some special edge cases (e.g. without defined models, migrations, etc.).
To run integration test just use standard spec runner:
$ crystal spec spec/integration/<test_name>.cr
Each test file is required to be invoked separately as it may have own configuration.
Documentation generation
Self documentation is not fully support yet but docs can be compiled using this shell script:
$ ./generate-docs.sh
NB. It also depends on then chosen adapter (postgres by default).
Contributing
- Fork it
- 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
Please ask me before starting work on smth. Also often there is a separate branch for the future minor release that includes all breaking changes.
Contributors
- imdrasil Roman Kalnytskyi - creator, maintainer