Class: GraphQL::Stitching::Supergraph

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql/stitching/supergraph.rb

Constant Summary collapse

LOCATION = 
"__super"
INTROSPECTION_TYPES = 
[
  "__Schema",
  "__Type",
  "__Field",
  "__Directive",
  "__EnumValue",
  "__InputValue",
  "__TypeKind",
  "__DirectiveLocation",
].freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema:, fields:, boundaries:, executables:) ⇒ Supergraph

Returns a new instance of Supergraph.



44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
 
# File 'lib/graphql/stitching/supergraph.rb', line 44

def initialize(schema:, fields:, boundaries:, executables:)
  @schema = schema
  @boundaries = boundaries
  @possible_keys_by_type = {}
  @possible_keys_by_type_and_location = {}

  # add introspection types into the fields mapping
  @locations_by_type_and_field = INTROSPECTION_TYPES.each_with_object(fields) do |type_name, memo|
    introspection_type = schema.get_type(type_name)
    next unless introspection_type.kind.fields?

    memo[type_name] = introspection_type.fields.keys.each_with_object({}) do |field_name, m|
      m[field_name] = [LOCATION]
    end
  end.freeze

  # validate and normalize executable references
  @executables = executables.each_with_object({ LOCATION => @schema }) do |(location, executable), memo|
    if self.class.validate_executable!(location, executable)
      memo[location.to_s] = executable
    end
  end.freeze
end

Instance Attribute Details

#boundaries ⇒ Object (readonly)

Returns the value of attribute boundaries.



42
43
44
 
# File 'lib/graphql/stitching/supergraph.rb', line 42

def boundaries
  @boundaries
end

#executables ⇒ Object (readonly)

Returns the value of attribute executables.



42
43
44
 
# File 'lib/graphql/stitching/supergraph.rb', line 42

def executables
  @executables
end

#locations_by_type_and_field ⇒ Object (readonly)

Returns the value of attribute locations_by_type_and_field.



42
43
44
 
# File 'lib/graphql/stitching/supergraph.rb', line 42

def locations_by_type_and_field
  @locations_by_type_and_field
end

#schema ⇒ Object (readonly)

Returns the value of attribute schema.



42
43
44
 
# File 'lib/graphql/stitching/supergraph.rb', line 42

def schema
  @schema
end

Class Method Details

.from_export(schema:, delegation_map:, executables:) ⇒ Object 



24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
 
# File 'lib/graphql/stitching/supergraph.rb', line 24

def self.from_export(schema:, delegation_map:, executables:)
  schema = GraphQL::Schema.from_definition(schema) if schema.is_a?(String)

  executables = delegation_map["locations"].each_with_object({}) do |location, memo|
    executable = executables[location] || executables[location.to_sym]
    if validate_executable!(location, executable)
      memo[location] = executable
    end
  end

  new(
    schema: schema,
    fields: delegation_map["fields"],
    boundaries: delegation_map["boundaries"],
    executables: executables,
  )
end

.validate_executable!(location, executable) ⇒ Object

Raises:



18
19
20
21
22
 
# File 'lib/graphql/stitching/supergraph.rb', line 18

def self.validate_executable!(location, executable)
  return true if executable.is_a?(Class) && executable <= GraphQL::Schema
  return true if executable && executable.respond_to?(:call)
  raise StitchingError, "Invalid executable provided for location `#{location}`."
end

Instance Method Details

#execute_at_location(location, source, variables, context) ⇒ Object 



84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
 
# File 'lib/graphql/stitching/supergraph.rb', line 84

def execute_at_location(location, source, variables, context)
  executable = executables[location]

  if executable.nil?
    raise StitchingError, "No executable assigned for #{location} location."
  elsif executable.is_a?(Class) && executable <= GraphQL::Schema
    executable.execute(
      query: source,
      variables: variables,
      context: context.frozen? ? context.dup : context,
      validate: false,
    )
  elsif executable.respond_to?(:call)
    executable.call(location, source, variables, context)
  else
    raise StitchingError, "Missing valid executable for #{location} location."
  end
end

#export ⇒ Object 



76
77
78
79
80
81
82
 
# File 'lib/graphql/stitching/supergraph.rb', line 76

def export
  return GraphQL::Schema::Printer.print_schema(@schema), {
    "locations" => locations,
    "fields" => fields,
    "boundaries" => @boundaries,
  }
end

#fields ⇒ Object 



68
69
70
 
# File 'lib/graphql/stitching/supergraph.rb', line 68

def fields
  @locations_by_type_and_field.reject { |k, _v| INTROSPECTION_TYPES.include?(k) }
end

#fields_by_type_and_location ⇒ Object

inverts fields map to provide fields for a type/location “Type” => “location” => [“field1”, “field2”, …]



105
106
107
108
109
110
111
112
113
114
 
# File 'lib/graphql/stitching/supergraph.rb', line 105

def fields_by_type_and_location
  @fields_by_type_and_location ||= @locations_by_type_and_field.each_with_object({}) do |(type_name, fields), memo|
    memo[type_name] = fields.each_with_object({}) do |(field_name, locations), memo|
      locations.each do |location|
        memo[location] ||= []
        memo[location] << field_name
      end
    end
  end
end

#locations ⇒ Object 



72
73
74
 
# File 'lib/graphql/stitching/supergraph.rb', line 72

def locations
  @executables.keys.reject { _1 == LOCATION }
end

#locations_by_type ⇒ Object

“Type” => [“location1”, “location2”, …]



117
118
119
120
121
 
# File 'lib/graphql/stitching/supergraph.rb', line 117

def locations_by_type
  @locations_by_type ||= @locations_by_type_and_field.each_with_object({}) do |(type_name, fields), memo|
    memo[type_name] = fields.values.flatten.uniq
  end
end

#possible_keys_for_type(type_name) ⇒ Object

collects all possible boundary keys for a given type (“Type”) => [“id”, …]



125
126
127
128
129
130
131
 
# File 'lib/graphql/stitching/supergraph.rb', line 125

def possible_keys_for_type(type_name)
  @possible_keys_by_type[type_name] ||= begin
    keys = @boundaries[type_name].map { _1["selection"] }
    keys.uniq!
    keys
  end
end

#possible_keys_for_type_and_location(type_name, location) ⇒ Object

collects possible boundary keys for a given type and location (“Type”, “location”) => [“id”, …]



135
136
137
138
139
140
141
 
# File 'lib/graphql/stitching/supergraph.rb', line 135

def possible_keys_for_type_and_location(type_name, location)
  possible_keys_by_type = @possible_keys_by_type_and_location[type_name] ||= {}
  possible_keys_by_type[location] ||= begin
    location_fields = fields_by_type_and_location[type_name][location] || []
    location_fields & possible_keys_for_type(type_name)
  end
end

#route_type_to_locations(type_name, start_location, goal_locations) ⇒ Object

For a given type, route from one origin location to one or more remote locations used to connect a partial type across locations via boundary queries



145
146
147
148
149
150
151
152
153
154
155
156
157
158
 
# File 'lib/graphql/stitching/supergraph.rb', line 145

def route_type_to_locations(type_name, start_location, goal_locations)
  if possible_keys_for_type(type_name).length > 1
    # multiple keys use an a-star search to traverse intermediary locations
    return route_type_to_locations_via_search(type_name, start_location, goal_locations)
  end

  # types with a single key attribute must all be within a single hop of each other,
  # so can use a simple match to collect boundaries for the goal locations.
  @boundaries[type_name].each_with_object({}) do |boundary, memo|
    if goal_locations.include?(boundary["location"])
      memo[boundary["location"]] = [boundary]
    end
  end
end