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APRIL 24, 2024

Another milestone reached with Lucky 1.2.0

We're well in to 2024 now. Crystal 1.12 is out, and so is Lucky 1.2.0. Let's check out all of the great new features and updates.

Lucky v1.2.0 has been released with lots of great new updates and features.

Read through the CHANGELOG for all of the changes, but we will discuss some of the highlights here.

# How to upgrade


You can also view the changes using LuckyDiff.

# Here’s what’s new

# Installing Lucky on Windows

While Lucky doesn’t quite have 100% Windows compatibility, we do have a way for you to start testing things by installing Lucky on Windows via Scoop.

This is a huge step forward for Crystal on Windows in general. As Crystal’s support for Windows grows, we will need to ensure the entire ecosystem is right there. You can check out our official scoop bucket for instructions on installing, or to help contribute.

# DB.mapping replaced with DB::Serializable

Avram models use crystal-db under the hood to build the columns. Previously we used DB.mapping to construct the columns, but as of this PR, that way has been deprecated in favor of using DB::Serializable. This is now more consistent with JSON::Serialzable and YAML::Serializable, but it does come with a small breaking change.

DB::Serializable is a module that is included in Avram::Model. It works by mapping the instance variables to columns in the database. This also means that any instance variable you’ve defined as custom will be mistaken for a database related column. To avoid this, you will need to add the annotation @[DB::Field(ignore: true)] to any instance variable you may have added in your model.

class MyModel < BaseModel
  table do
    column name : String

  @[DB::Field(ignore: true)]
  property special_field : String

# Lots of new Critera methods

The Criteria methods in Avram are query methods used around specific column types. For example, the String column types have criteria methods upper and lower which allow you to transform the column with UPPER(col) or LOWER(col) which can be used for special comparrisons.

In this release, we have added a LOT more. The String type added length and reverse. Int and Float types received a few abs, ceil, and floor.

# Find all users that have a username length of 8

# Find all cards with this palindrome"tacocat")

# Find all purchases where the rounded-up amount is greater than 5

# Turn a negative number in to positive, and use in your query

To add to these great methods, we’ve also added JSON::Any critera methods. Querying jsonb fields can be a bit tricky, and Avram now allows you to avoid a few unsafe raw WHERE queries by using type-safe ones.

# Where the preferences jsonb has the key 'theme'"theme")

# Where the preferences jsonb has the key 'theme' or the key 'color'["theme", "color"])

# Where the preferences jsonb has the key 'theme' and the key 'color'["theme", "color"])

# Where the preferences jsonb contains the JSON {"theme": "dark"}{theme: "dark"})

# Where the preferences jsonb is found in this json document

Finally, String also received a few more Criteria related to Full-Text searching.

Convert a String column to_tsquery or to_tsvector by using those methods names in conjunction with the new match method.

# SELECT * FROM profiles WHERE TO_TSVECTOR(description) @@ TO_TSQUERY('Lucky')"Lucky")

# New migration methods

Migrations received a few updates. You can now run your create and alter conditionally with if_not_exists and if_exists respectively.

# Only create the table if it does not already exist
create table_for(Server), if_not_exists: true do
  add hostname : String

You can also ignore the index created on add_belongs_to by specifying index: false.

alter table_for(Reaction), if_exists: true do
  add_belongs_to user : User?, index: false
  add_belongs_to friend : User?, index: false

This will allow you to create a custom, unique index utilizing multiple columns instead of separate indexes on each column.

We’ve also added the create_sequence and drop_sequence helpers.

def migrate
  create_sequence table_for(Account), :number

def rollback
  drop_sequence table_for(Account), :number

# The IGNORE constant

In Avram, the attributes defined on operations are a union of the type you specified, and Avram::Nothing. Passing nil during an operation sets a value to NULL in the database. In contrast, using Avram::Nothing ignores the value; the value is unchanged.

Previously, each attribute would define a default value of The larger your application grew, the more instances of Avram::Nothing you would have. These have all been replaced with a single instance of Avram::Nothing assigned as the constant IGNORE.

Use the IGNORE constant in place of instantiating Avram::Nothing when you want to fallback to ignoring a column in a SaveOperation.

# Before the update
  email: new_email.presence ||

# After the update
# If `new_email.presence` is nil, then just ignore this update
  email: new_email.presence || IGNORE

# Email attachments

Carbon received a nice update that adds of attachment support.

class BirthdayEmail < BaseEmail
  def initiailize(@recipient : Carbon::Emailable)
    @image ="birthday_cake.png") do |f|
      IO.copy(f, @image)

  subject "Happy Birthday"
  to @recipient
  templates html
  attachment cake

  def cake
      io: @image,
      file_name: "birthday_cake.png",
      mime_type: "image/png"

# even more!

Beyond the major changes listed above, there were quite a few updates in this release:

  • Support for Array(Enum) columns
  • Support for String primary keys
  • Firefox LuckyFlow driver
  • Added option to lucky gen.secret_key task
  • More CockroachDB compatibility
  • A materialized view helper method refresh_view
  • Custom column converters
  • DB connection retries
  • Route building optimizations
  • Compilation time printed during development
  • Bug fixes

# Parting words

Thanks to all of the new developers giving Lucky a shot. The more people that try it out, the better we can make the framework. If you’re using Lucky in production, and would like to add your application to our Awesome Lucky “built-with” section, feel free to open an issue on the Website or a PR!

# Follow and spread the word

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