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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

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

Returns a new instance of Base.

Parameters:

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


25
26
27
28
 
# File 'lib/deimos/schema_backends/base.rb', line 25

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

Instance Attribute Details

#key_schema ⇒ Object

Returns the value of attribute key_schema.



21
22
23
 
# File 'lib/deimos/schema_backends/base.rb', line 21

def key_schema
  @key_schema
end

#namespace ⇒ Object

Returns the value of attribute namespace.



21
22
23
 
# File 'lib/deimos/schema_backends/base.rb', line 21

def namespace
  @namespace
end

#schema ⇒ Object

Returns the value of attribute schema.



21
22
23
 
# File 'lib/deimos/schema_backends/base.rb', line 21

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:

  • (NotImplementedError) 


77
78
79
 
# File 'lib/deimos/schema_backends/base.rb', line 77

def self.content_type
  raise NotImplementedError
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 (e.g. avro_validation) 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) 


71
72
73
 
# File 'lib/deimos/schema_backends/base.rb', line 71

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) 


52
53
54
55
56
57
58
59
60
61
62
 
# File 'lib/deimos/schema_backends/base.rb', line 52

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:

  • (NotImplementedError) 


117
118
119
 
# File 'lib/deimos/schema_backends/base.rb', line 117

def coerce_field(_field, _value)
  raise NotImplementedError
end

#decode(payload, schema: nil) ⇒ Hash?

Decode a payload with a schema. Public method.

Parameters:

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

Returns:

  • (Hash, nil) 


44
45
46
47
 
# File 'lib/deimos/schema_backends/base.rb', line 44

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 (Symbol|String) —

    the field in the message to decode.

Returns:

  • (String)

Raises:

  • (NotImplementedError) 


145
146
147
 
# File 'lib/deimos/schema_backends/base.rb', line 145

def decode_key(_payload, _key_id)
  raise NotImplementedError
end

#decode_payload(_payload, schema:) ⇒ Hash

Decode a payload. To be defined by subclass.

Parameters:

  • payload (String)
  • schema (String|Symbol)

Returns:

  • (Hash)

Raises:

  • (NotImplementedError) 


94
95
96
 
# File 'lib/deimos/schema_backends/base.rb', line 94

def decode_payload(_payload, schema:)
  raise NotImplementedError
end

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

Encode a payload with a schema. Public method.

Parameters:

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

Returns:

  • (String) 


35
36
37
38
 
# File 'lib/deimos/schema_backends/base.rb', line 35

def encode(payload, schema: nil, topic: nil)
  validate(payload, schema: schema || @schema)
  encode_payload(payload, schema: schema || @schema, topic: topic)
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 (Symbol|String) —

    the field name of the key.

  • topic (String) (defaults to: nil)

Returns:

  • (String)

Raises:

  • (NotImplementedError) 


137
138
139
 
# File 'lib/deimos/schema_backends/base.rb', line 137

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

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

Encode a payload. To be defined by subclass.

Parameters:

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

Returns:

  • (String)

Raises:

  • (NotImplementedError) 


86
87
88
 
# File 'lib/deimos/schema_backends/base.rb', line 86

def encode_payload(_payload, schema:, topic: nil)
  raise NotImplementedError
end

#schema_fields ⇒ Array<SchemaField>

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

Returns:

Raises:

  • (NotImplementedError) 


107
108
109
 
# File 'lib/deimos/schema_backends/base.rb', line 107

def schema_fields
  raise NotImplementedError
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:

  • (NotImplementedError) 


128
129
130
 
# File 'lib/deimos/schema_backends/base.rb', line 128

def sql_type(field)
  raise NotImplementedError
end

#validate(_payload, schema:) ⇒ Object

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

Parameters:

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

Raises:

  • (NotImplementedError) 


101
102
103
 
# File 'lib/deimos/schema_backends/base.rb', line 101

def validate(_payload, schema:)
  raise NotImplementedError
end