Module: GraphQL::StaticValidation::VariablesAreUsedAndDefined

Defined in:
lib/graphql/static_validation/rules/variables_are_used_and_defined.rb

Overview

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

Defined Under Namespace

Classes: VariableUsage

Instance Method Summary collapse

Instance Method Details

#initializeObject


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# File 'lib/graphql/static_validation/rules/variables_are_used_and_defined.rb', line 26

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

#on_document(node, parent) ⇒ Object


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# File 'lib/graphql/static_validation/rules/variables_are_used_and_defined.rb', line 78

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

#on_fragment_definition(node, parent) ⇒ Object


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# File 'lib/graphql/static_validation/rules/variables_are_used_and_defined.rb', line 48

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

#on_fragment_spread(node, parent) ⇒ Object

For FragmentSpreads:

  • find the context on the stack
  • mark the context as containing this spread

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# File 'lib/graphql/static_validation/rules/variables_are_used_and_defined.rb', line 59

def on_fragment_spread(node, parent)
  variable_context = @variable_context_stack.last
  @spreads_for_context[variable_context] << node.name
  super
end

#on_operation_definition(node, parent) ⇒ Object


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# File 'lib/graphql/static_validation/rules/variables_are_used_and_defined.rb', line 33

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

#on_variable_identifier(node, parent) ⇒ Object

For VariableIdentifiers:

  • mark the variable as used
  • assign its AST node

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# File 'lib/graphql/static_validation/rules/variables_are_used_and_defined.rb', line 68

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