Mongoid::Avro

The mongoid-avro is a Ruby gem that allows you to convert a Mongoid Model schema into an Avro schema. This can be useful if you want to use Avro serialization with your Mongoid data.

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Installation

To install mongoid-avro, add it to your Gemfile:

gem 'mongoid-avro'

Then, execute the following command:

bundle install

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Usage

1. Include Mongoid::Avro in your Mongoid model:

class MyModel
  include Mongoid::Document
  include Mongoid::Avro
  # ...
end

2. Optionally, you can specify the Avro format for each field using the avro_format option:

class MyModel
  include Mongoid::Document
  include Mongoid::Avro

  field :my_field, type: String, avro_format: 'my_custom_format'
  field :my_field_2, type: String, avro_format: {
      type: 'record',
      name: 'Money',
      fields: [
        { name: 'cents', type: 'int' },
        { name: 'currency_iso', type: 'string' }
      ]
    }
  # ...
end

The avro_format option can be a String, Symbol, or Hash.

2. Optionally, you can specify the avro_doc option to add a description of the field. It will be used as the doc of the field.

class Person
  include Mongoid::Document
  include Mongoid::Avro

  field :unique_name, type: String, avro_doc: 'The name of the person which is unique.'
end

3. To generate the Avro schema for your model, call the .generate_avro_schema method :

schema = MyModel.generate_avro_schema(namespace: 'my.namespace')

You can pass an optional namespace parameter to specify the namespace for the Avro schema. The method returns an Avro::Schema object.

The method returns an Avro::Schema.

4. (Optional) Generate Avro schema as JSON:

schema.to_avro.to_json

---

Field type transform login

Primitive Types

Mongoid	Avro
_id field	string
Integer	int
Float	double
String	string
Symbol	string
Boolean	boolean
BSON::ObjectId	string

Complext Types

DateTime, Time

{ "type": "long", "logicalType": "timestamp-millis"}

Date

{ "type": "int", "logicalType": "Date"}

Money

{
  "type": "record",
  "name": "Money",
  "fields": [
    {
      "name": "cents",
      "type": "long"
    },
    {
      "name": "currency_iso",
      "type": "string"
    }
  ]
}

Array: Array of strings

{
  "type": "array",
  "items": "string",
  "default": []
}

Hash: string

{
  "type": "string",
  "logicalType": "json"
}

Embedded document

Embeds One

{
  "name": "unique_address",
  "type": [
    "null",
    {
      "type": "record",
      "name": "unique_address",
      "namespace": "ns1",
      "fields": [
        {
          "name": "_id",
          "type": "string"
        },
        {
          "name": "address",
          "type": "string"
        },
        {
          "name": "number",
          "type": "int"
        }
      ]
    }
  ]
}

Embeds Many

{
  "name": "multiple_address",
  "type": [
    "null",
    {
      "type": "array",
      "items": {
        "type": "record",
        "name": "multiple_address",
        "namespace": "ns1",
        "fields": [
          {
            "name": "_id",
            "type": "string"
          },
          {
            "name": "address",
            "type": "string"
          },
          {
            "name": "number",
            "type": "int"
          }
        ]
      }
    }
  ]
}

Associations

BelongsTo: string as forigen key

HasAndBelongsToMany: same as an Array

{
  "type": "array",
  "items": "string",
  "default": []
}

---

Validation

require 'mongoid-avro'

MyModel.include(Mongoid::Avro)
schema = MyModel.generate_avro_schema(namespace: 'my.namespace')
model = MyModel.find('id')
test_data = JSON.parse(model.attributes.to_json)
Avro::SchemaValidator.validate!(schema, data)

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/shoplineapp/mongoid-avro.

License

The gem is available as open source under the terms of the MIT License.