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OCTOBER 7, 2019

Lucky 0.18 is out now.

Lucky v0.18 introduces many improvements to building JSON APIs. Better serialization, built-in JWT auth, and improved error handling.

Lucky v0.18 is now out and requires the newest version of Crystal (v0.31.1)

Be sure to upgrade your version of Crystal, and take a look at our UPGRADE NOTES for help with migrating your app.

# What’s new?

We’ve made a ton of changes for this release, but we will highlight a few. You can see a full list through our CHANGELOG.

# Built in JWT (JSON Web Token) authentication

When generating a new app with lucky init you will be asked if you want Lucky to include authentication. If you choose “yes” Lucky will now include code for signing up users, and creating a token that can be used to authenticate users with your API.

Read more about it in the API Authentication guide.

# Improved serializers

Before Lucky 0.18.0 we recommended creating two serializers for each resource. One for rendering a single item, and another for rendering a collection. This led to a lot of files and code doing the same thing. Now Lucky generates a BaseSerializer that includes a for_collection method.

That means you only need one class:

class UserSerializer < BaseSerializer
  def initialize(@user : User)

  def render
    {id:, name:}

And it can render one User or a collection of Users:

# Serialize one user

# Serialize a collection of users

Learn more in the JSON rendering guide

# Added between to queries

Added a new between criteria method to making querying easier:, Time.utc)

# Improved error handling

Previously error handling had lots of conditional logic that made it hard to tell what was happening. Now many errors are handled automatically, and it is easier to change how an error is rendered to a user.

For example if you wanted to customize how MyCustomError was rendered:

class Errors::Show < Lucky::ErrorAction
  def render(error : MyCustomError)
    error_json "This is a custom error message", status: 418

More in the error handling guide

# Error reporting

We’ve also introduced a way to easily report errors. Lucky generates an Errors::Show class with a new report method that is empty. You can fill in the method to report it however you want.

For example, we could use the Raven shard to send an error report to Sentry:

# src/actions/errors/
def report(error : Exception)

Read more about error reporting.

# Keep your database and schema in sync

We’ve added a new feature called Schema Enforcer that runs when your server is started and in development or test mode. If you have a missing column, table, or incorrect type, Lucky will let you know.

For example if we wanted to use a slug column in the Post model but we forgot to add it:

Post wants to use the column 'slug' but it does not exist.

Try adding the column to the table...

  ▸ Generate a migration:

      lucky gen.migration AddSlugToPosts

  ▸ Add the column to the migration:

      alter :posts do
        add slug : String

# Parting words

We’re very excited about this release, and hope you are too. Please give it a spin and help us find bugs so our next release is even more solid. If you find any issues, don’t hesitate to report the issue. If you’re unsure, just hop on gitter chat so we can help you out.

Thanks so much for the support!

# Follow and spread the word

If you haven’t already, give us a star on github, and be sure to follow us on Twitter.

For questions, or just to chat, come say hi on gitter.