Class: Deimos::SchemaBackends::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/deimos/schema_backends/base.rb

Overview

Base class for encoding / decoding.

Direct Known Subclasses

AvroBase, Mock, Plain, ProtoBase

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema:, namespace: nil, registry_info: nil) ⇒ Base

Returns a new instance of Base.

Parameters:

  • schema (String, Symbol)
  • namespace (String) (defaults to: nil) 


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# File 'lib/deimos/schema_backends/base.rb', line 59

def initialize(schema:, namespace: nil, registry_info: nil)
  @schema = schema
  @namespace = namespace
  @registry_info = registry_info
end

Instance Attribute Details

#key_schema ⇒ String

Returns:

  • (String) 


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# File 'lib/deimos/schema_backends/base.rb', line 53

def key_schema
  @key_schema
end

#namespace ⇒ String

Returns:

  • (String) 


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# File 'lib/deimos/schema_backends/base.rb', line 51

def namespace
  @namespace
end

#registry_info ⇒ RegistryInfo

Returns:



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# File 'lib/deimos/schema_backends/base.rb', line 55

def registry_info
  @registry_info
end

#schema ⇒ String

Returns:

  • (String) 


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# File 'lib/deimos/schema_backends/base.rb', line 49

def schema
  @schema
end

Class Method Details

.content_type ⇒ String

The content type to use when encoding / decoding requests over HTTP via ActionController.

Returns:

  • (String)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 130

def self.content_type
  raise MissingImplementationError
end

.field_type(_schema) ⇒ String

Converts your schema to String form for generated YARD docs. To be defined by subclass.

Parameters:

  • schema (Object)

Returns:

  • (String) —

    A string representation of the Type

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 138

def self.field_type(_schema)
  raise MissingImplementationError
end

.mock_backend ⇒ Symbol

Indicate a class which should act as a mocked version of this backend. This class should perform all validations but not actually do any encoding. Note that the “mock” version should return its own symbol when this is called, since it may be called multiple times depending on the order of RSpec helpers.

Returns:

  • (Symbol) 


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# File 'lib/deimos/schema_backends/base.rb', line 124

def self.mock_backend
  :mock
end

Instance Method Details

#coerce(payload) ⇒ Hash

Given a hash, coerce its types to our schema. To be defined by subclass.

Parameters:

  • payload (Hash)

Returns:

  • (Hash) 


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# File 'lib/deimos/schema_backends/base.rb', line 105

def coerce(payload)
  result = {}
  self.schema_fields.each do |field|
    name = field.name
    next unless payload.key?(name)

    val = payload[name]
    result[name] = coerce_field(field, val)
  end
  result.with_indifferent_access
end

#coerce_field(_field, _value) ⇒ Object

Given a value and a field definition (as defined by whatever the underlying schema library is), coerce the given value to the given field type.

Parameters:

Returns:

  • (Object)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 179

def coerce_field(_field, _value)
  raise MissingImplementationError
end

#decode(payload, schema: nil) ⇒ Hash?

Decode a payload with a schema. Public method.

Parameters:

  • payload (String)
  • schema (String, Symbol) (defaults to: nil)

Returns:

  • (Hash, nil) 


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# File 'lib/deimos/schema_backends/base.rb', line 96

def decode(payload, schema: nil)
  return nil if payload.nil?

  decode_payload(payload, schema: schema || @schema)
end

#decode_key(_payload, _key_id) ⇒ String

Decode a message key. To be defined by subclass.

Parameters:

  • payload (Hash) —

    the message itself.

  • key_id (String, Symbol) —

    the field in the message to decode.

Returns:

  • (String)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 214

def decode_key(_payload, _key_id)
  raise MissingImplementationError
end

#decode_payload(_payload, schema:) ⇒ Hash

Decode a payload. To be defined by subclass.

Parameters:

  • payload (String)
  • schema (String, Symbol)

Returns:

  • (Hash)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 155

def decode_payload(_payload, schema:)
  raise MissingImplementationError
end

#encode(payload, schema: nil, topic: nil, is_key: false) ⇒ String

Encode a payload with a schema. Public method.

Parameters:

  • payload (Hash)
  • schema (String, Symbol) (defaults to: nil)
  • topic (String) (defaults to: nil)

Returns:

  • (String) 


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# File 'lib/deimos/schema_backends/base.rb', line 85

def encode(payload, schema: nil, topic: nil, is_key: false)
  validate(payload, schema: schema || @schema)
  subject = topic.presence || schema
  subject = is_key ? "#{subject}-key" : "#{subject}-value"
  encode_payload(payload, schema: schema || @schema, subject: subject)
end

#encode_key(_key, _key_id, topic: nil) ⇒ String

Encode a message key. To be defined by subclass.

Parameters:

  • key (String, Hash) —

    the value to use as the key.

  • key_id (String, Symbol) —

    the field name of the key.

  • topic (String) (defaults to: nil)

Returns:

  • (String)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 206

def encode_key(_key, _key_id, topic: nil)
  raise MissingImplementationError
end

#encode_payload(_payload, schema:, subject: nil) ⇒ String

Encode a payload. To be defined by subclass.

Parameters:

  • payload (Hash)
  • schema (String, Symbol)
  • subject (String) (defaults to: nil)

Returns:

  • (String)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 147

def encode_payload(_payload, schema:, subject: nil)
  raise MissingImplementationError
end

#generate_key_schema(_field_name) ⇒ Object

Generate a key schema from the given value schema and key ID. This is used when encoding or decoding keys from an existing value schema.

Parameters:

  • field_name (Symbol)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 197

def generate_key_schema(_field_name)
  raise MissingImplementationError
end

#inspect ⇒ String

Returns:

  • (String) 


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# File 'lib/deimos/schema_backends/base.rb', line 66

def inspect
  "Type #{self.class.name.demodulize} Schema: #{@namespace}.#{@schema} Key schema: #{@key_schema}"
end

#load_schema ⇒ Object

Forcefully loads the schema into memory.

Returns:

  • (Object) —

    The schema that is of use.

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 220

def load_schema
  raise MissingImplementationError
end

#schema_fields ⇒ Array<SchemaField>

List of field names belonging to the schema. To be defined by subclass.

Returns:

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 169

def schema_fields
  raise MissingImplementationError
end

#sql_type(_field) ⇒ Symbol

Given a field definition, return the SQL type that might be used in ActiveRecord table creation - e.g. for Avro, a long type would return :bigint. There are also special values that need to be returned: :array, :map and :record, for types representing those structures. :enum is also recognized.

Parameters:

Returns:

  • (Symbol)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 190

def sql_type(_field)
  raise MissingImplementationError
end

#supports_class_generation? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/deimos/schema_backends/base.rb', line 76

def supports_class_generation?
  false
end

#supports_key_schemas? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/deimos/schema_backends/base.rb', line 71

def supports_key_schemas?
  false
end

#validate(_payload, schema:) ⇒ void

This method returns an undefined value.

Validate that a payload matches the schema. To be defined by subclass.

Parameters:

  • payload (Hash)
  • schema (String, Symbol)

Raises:



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# File 'lib/deimos/schema_backends/base.rb', line 163

def validate(_payload, schema:)
  raise MissingImplementationError
end