### Install JSONAPI.rb Gem

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Instructions for adding the JSONAPI.rb gem to your application's Gemfile and installing it using Bundler, or installing it directly via RubyGems.

```ruby
gem 'jsonapi.rb'
```

--------------------------------

### Install JSONAPI.rb via Shell

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Command to install the JSONAPI.rb gem directly using the gem command-line tool.

```shell
$ gem install jsonapi.rb
```

--------------------------------

### JSONAPI.rb Includes and Sparse Fields

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Illustrates how to use JSONAPI::Fetching to include related resources and serialize only specific fields. It shows how to whitelist includes and provides an example of a curl command for fetching sparse fields.

```ruby
class MyController < ActionController::Base
  include JSONAPI::Fetching

  def index
    render jsonapi: Model.all
  end

  private

  # Overwrite/whitelist the includes
  def jsonapi_include
    super & ['wanted_attribute']
  end
end
```

```bash
$ curl -X GET /api/resources?fields[model]=model_attr,relationship
```

--------------------------------

### JSONAPI.rb Pagination

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Shows how to implement pagination for model record sets using JSONAPI::Pagination. Includes examples for rendering paginated results, adding pagination info to meta, and customizing the page size.

```ruby
class MyController < ActionController::Base
  include JSONAPI::Pagination

  def index
    jsonapi_paginate(Model.all) do |paginated|
      render jsonapi: paginated
    end
  end

end
```

```ruby
  def jsonapi_meta(resources)
    pagination = jsonapi_pagination_meta(resources)

    { pagination: pagination } if pagination.present?
  end


```

```ruby
  def jsonapi_page_size(pagination_params)
    per_page = pagination_params[:size].to_f.to_i
    per_page = 30 if per_page > 30 || per_page < 1
    per_page
  end
```

--------------------------------

### Collection Meta Information in Rails

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Example of providing meta information for a JSON:API collection response in a Rails controller by implementing the `jsonapi_meta` method, often used for pagination details like total counts.

```ruby
class MyController < ActionController::Base
  def index
    render jsonapi: Model.all
  end

  private

  def jsonapi_meta(resources)
    { total: resources.count } if resources.respond_to?(:count)
  end
end
```

--------------------------------

### Custom Serializer Class Naming in Rails

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Example of how to implement `jsonapi_serializer_class` in a Rails controller to customize the naming convention for JSON:API serializers when the default naming scheme does not apply.

```ruby
class CustomNamingController < ActionController::Base

  # ...

  private

  def jsonapi_serializer_class(resource, is_collection)
    JSONAPI::Rails.serializer_class(resource, is_collection)
rescue NameError
    # your serializer class naming implementation
  end
end
```

--------------------------------

### Enable JSONAPI.rb for Rails

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Code snippet to include in a Rails initializer to enable JSONAPI.rb support. This registers the necessary mime types and renderers (`jsonapi` and `jsonapi_errors`) for Rails integration.

```ruby
# config/initializers/jsonapi.rb
require 'jsonapi'

JSONAPI::Rails.install!
```

--------------------------------

### JSONAPI.rb Error Handling

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Demonstrates how to use JSONAPI::Errors for handling exceptions, strong parameters errors, generic errors, and record not found scenarios. It shows how to render validation errors and override the internal server error method for exception notification.

```ruby
class MyController < ActionController::Base
  include JSONAPI::Errors

  def update
    record = Model.find(params[:id])

    if record.update(params.require(:data).require(:attributes).permit!)
      render jsonapi: record
    else
      render jsonapi_errors: record.errors, status: :unprocessable_entity
    end
  end

  private

  def render_jsonapi_internal_server_error(exception)
    # Call your exception notifier here. Example:
    # Raven.capture_exception(exception)
    super(exception)
  end
end
```

--------------------------------

### JSONAPI.rb Filtering and Sorting with Ransack

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Explains how to use JSONAPI::Filtering with Ransack for advanced filtering and sorting of record collections, including support for relationships and composite matchers. Requires adding `ransack` to the Gemfile.

```ruby
class MyController < ActionController::Base
  include JSONAPI::Filtering

  def index
    allowed = [:model_attr, :relationship_attr]

    jsonapi_filter(Model.all, allowed) do |filtered|
      render jsonapi: filtered.result
    end
  end
end
```

```bash
$ curl -X GET \
  /api/resources?filter[model_attr_or_relationship_attr_cont_any]=value,name\
  &sort=-model_attr,relationship_attr
```

--------------------------------

### JSONAPI.rb Sorting with Expressions

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Details how to enable sorting using SQL aggregations like min, max, avg, sum, and count within JSONAPI.rb filtering. This requires enabling the `sort_with_expressions` option and potentially grouping results.

```ruby
options = { sort_with_expressions: true }
jsonapi_filter(User.all, allowed_fields, options) do |filtered|
  render jsonapi: filtered.result.group('id').to_a
end
```

```bash
$ curl -X GET /api/resources?sort=-model_attr_sum
```

--------------------------------

### Custom Serializer Parameters in Rails

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Demonstrates implementing `jsonapi_serializer_params` in a Rails controller to pass custom parameters to the JSON:API serializer, such as controlling field formatting based on request parameters.

```ruby
class CustomSerializerParamsController < ActionController::Base

  # ...

  private

  def jsonapi_serializer_params
    {
      first_name_upcase: params[:upcase].present?
    }
  end
end
```

--------------------------------

### Deserialize JSONAPI Payload in Rails Controller

Source: https://github.com/stas/jsonapi.rb/blob/master/README.md

Demonstrates how to use the `jsonapi_deserialize` helper within a Rails controller action to update an ActiveRecord model with data from a JSONAPI payload. It shows how to handle successful updates and validation errors.

```ruby
class MyController < ActionController::Base
  include JSONAPI::Deserialization

  def update
    model = MyModel.find(params[:id])

    if model.update(jsonapi_deserialize(params, only: [:attr1, :rel_one]))
      render jsonapi: model
    else
      render jsonapi_errors: model.errors, status: :unprocessable_entity
    end
  end
end
```

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