Mapping¶

Overview¶

The Mapping module translates between developer-friendly snake_case attribute names and native MQSC parameter names. Mapping is bidirectional: request attributes are mapped from snake_case to MQSC, and response attributes are mapped from MQSC to snake_case.

Controlling mapping¶

Session parameter	Default	Effect
`map_attributes:`	`true`	Enable/disable mapping
`mapping_strict:`	`false`	Raise on unknown attributes

Mapping override modes¶

Mode	Symbol	Behavior
Merge	`:merge`	Sparse overlay on built-in data
Replace	`:replace`	Complete replacement of built-in data

Mapping data structure¶

Each qualifier has up to five sub-maps:

Sub-map	Direction	Description
`request_key_map`	Request	`snake_case` key -> MQSC key
`request_value_map`	Request	`snake_case` value -> MQSC value
`request_key_value_map`	Request	Combined key+value mapping
`response_key_map`	Response	MQSC key -> `snake_case` key
`response_value_map`	Response	MQSC value -> `snake_case` value

MappingIssue¶

When mapping encounters unknown attributes or values, it records issues as MappingIssue objects:

Field	Type	Description
`direction`	`String`	`'request'` or `'response'`
`reason`	`String`	`'unknown_key'` or `'unknown_value'`
`attribute_name`	`String`	The attribute that couldn't be mapped
`attribute_value`	Object	The value (if applicable)
`object_index`	`Integer` or `nil`	Index in response list
`qualifier`	`String` or `nil`	The qualifier context

MappingError¶

In strict mode, MappingError is raised with an issues attribute containing the array of MappingIssue objects:

begin
  session.display_queue(name: '*', unknown_attr: 'value')
rescue MQ::REST::Admin::MappingError => e
  e.issues.each do |issue|
    puts "#{issue.direction}: #{issue.reason} for '#{issue.attribute_name}'"
  end
end

Module methods¶

For direct mapping without a session:

# Request direction
mapped = MQ::REST::Admin::Mapping.map_request_attributes(
  'queue',
  { 'description' => 'test' },
  strict: false
)

# Response direction
mapped = MQ::REST::Admin::Mapping.map_response_attributes(
  'queue',
  { 'DESCR' => 'test' },
  strict: false
)

# Batch response mapping
mapped = MQ::REST::Admin::Mapping.map_response_list(
  'queue',
  [{ 'DESCR' => 'test' }],
  strict: false
)