module GraphQL::StaticValidation::VariablesAreUsedAndDefined

The problem is - Variable $usage must be determined at the OperationDefinition level - You can’t tell how fragments use variables until you visit FragmentDefinitions (which may be at the end of the document)

So, this validator includes some crazy logic to follow fragment spreads recursively, while avoiding infinite loops.

graphql-js solves this problem by: - re-visiting the AST for each validator - allowing validators to say followSpreads: true

Public Class Methods

new (*)

Source

# File lib/graphql/static_validation/rules/variables_are_used_and_defined.rb, line 29
def initialize(*)
  super
  @variable_usages_for_context = Hash.new {|hash, key| hash[key] = Hash.new {|h, k| h[k] = VariableUsage.new } }
  @spreads_for_context = Hash.new {|hash, key| hash[key] = [] }
  @variable_context_stack = []
end

Calls superclass method

Public Instance Methods

on_document (node, parent)

Source

# File lib/graphql/static_validation/rules/variables_are_used_and_defined.rb, line 81
def on_document(node, parent)
  super
  fragment_definitions = @variable_usages_for_context.select { |key, value| key.is_a?(GraphQL::Language::Nodes::FragmentDefinition) }
  operation_definitions = @variable_usages_for_context.select { |key, value| key.is_a?(GraphQL::Language::Nodes::OperationDefinition) }

  operation_definitions.each do |node, node_variables|
    follow_spreads(node, node_variables, @spreads_for_context, fragment_definitions, [])
    create_errors(node_variables)
  end
end

Calls superclass method

on_fragment_definition (node, parent)

Source

# File lib/graphql/static_validation/rules/variables_are_used_and_defined.rb, line 51
def on_fragment_definition(node, parent)
  # initialize the hash of vars for this context:
  @variable_usages_for_context[node]
  @variable_context_stack.push(node)
  super
  @variable_context_stack.pop
end

Calls superclass method

on_fragment_spread (node, parent)

Source

# File lib/graphql/static_validation/rules/variables_are_used_and_defined.rb, line 62
def on_fragment_spread(node, parent)
  variable_context = @variable_context_stack.last
  @spreads_for_context[variable_context] << node.name
  super
end

For FragmentSpreads: - find the context on the stack - mark the context as containing this spread

Calls superclass method

on_operation_definition (node, parent)

Source

# File lib/graphql/static_validation/rules/variables_are_used_and_defined.rb, line 36
def on_operation_definition(node, parent)
  # initialize the hash of vars for this context:
  @variable_usages_for_context[node]
  @variable_context_stack.push(node)
  # mark variables as defined:
  var_hash = @variable_usages_for_context[node]
  node.variables.each { |var|
    var_usage = var_hash[var.name]
    var_usage.declared_by = node
    var_usage.path = context.path
  }
  super
  @variable_context_stack.pop
end

Calls superclass method

on_variable_identifier (node, parent)

Source

# File lib/graphql/static_validation/rules/variables_are_used_and_defined.rb, line 71
def on_variable_identifier(node, parent)
  usage_context = @variable_context_stack.last
  declared_variables = @variable_usages_for_context[usage_context]
  usage = declared_variables[node.name]
  usage.used_by = usage_context
  usage.ast_node = node
  usage.path = context.path
  super
end

For VariableIdentifiers: - mark the variable as used - assign its AST node

Calls superclass method