class GraphQL::Schema::FieldExtension
Extend this class to make field-level customizations to resolve behavior.
When a extension is added to a field with `extension(MyExtension)`, a `MyExtension` instance is created, and its hooks are applied whenever that field is called.
The instance is frozen so that instance variables aren't modified during query execution, which could cause all kinds of issues due to race conditions.
Constants
- NO_EXTRAS
Attributes
@return [Array<Symbol>, nil] `default_argument`s added, if any were added (otherwise, `nil`)
@api private
@return [GraphQL::Schema::Field]
@return [Object]
Public Class Methods
@see Argument#initialize @see HasArguments#argument
# File lib/graphql/schema/field_extension.rb, line 48 def default_argument(*argument_args, **argument_kwargs) configs = @own_default_argument_configurations ||= [] configs << [argument_args, argument_kwargs] end
@return [Array(Array, Hash), nil] A list of default argument configs, or `nil` if there aren't any
# File lib/graphql/schema/field_extension.rb, line 34 def default_argument_configurations args = superclass.respond_to?(:default_argument_configurations) ? superclass.default_argument_configurations : nil if @own_default_argument_configurations if args args.concat(@own_default_argument_configurations) else args = @own_default_argument_configurations.dup end end args end
If configured, these `extras` will be added to the field if they aren't already present, but removed by from `arguments` before the field's `resolve` is called. (The extras will be present for other extensions, though.)
@param new_extras [Array<Symbol>] If provided, assign extras used by this extension @return [Array<Symbol>] any extras assigned to this extension
# File lib/graphql/schema/field_extension.rb, line 59 def extras(new_extras = nil) if new_extras @own_extras = new_extras end inherited_extras = self.superclass.respond_to?(:extras) ? superclass.extras : nil if @own_extras if inherited_extras inherited_extras + @own_extras else @own_extras end elsif inherited_extras inherited_extras else NO_EXTRAS end end
Called when the extension is mounted with `extension(name, options)`. The instance will be frozen to avoid improper use of state during execution. @param field [GraphQL::Schema::Field] The field where this extension was mounted @param options [Object] The second argument to `extension`, or `{}` if nothing was passed.
# File lib/graphql/schema/field_extension.rb, line 25 def initialize(field:, options:) @field = field @options = options || {} @added_default_arguments = nil apply end
Public Instance Methods
Called after the field's definition block has been executed. (Any arguments from the block are present on `field`) @return [void]
# File lib/graphql/schema/field_extension.rb, line 91 def after_define end
@api private
# File lib/graphql/schema/field_extension.rb, line 95 def after_define_apply after_define if (configs = self.class.default_argument_configurations) existing_keywords = field.all_argument_definitions.map(&:keyword) existing_keywords.uniq! @added_default_arguments = [] configs.each do |config| argument_args, argument_kwargs = config arg_name = argument_args[0] if !existing_keywords.include?(arg_name) @added_default_arguments << arg_name field.argument(*argument_args, **argument_kwargs) end end end if (extras = self.class.extras).any? @added_extras = extras - field.extras field.extras(@added_extras) else @added_extras = nil end freeze end
Called after {#field} was resolved, and after any lazy values (like `Promise`s) were synced, but before the value was added to the GraphQL
response.
Whatever this hook returns will be used as the return value.
@param object [Object] The object the field is being resolved on @param arguments [Hash] Ruby keyword arguments for resolving this field @param context [Query::Context] the context for this query @param value [Object] Whatever the field previously returned @param memo [Object] The third value yielded by {#resolve}, or `nil` if there wasn't one @return [Object] The return value for this field.
# File lib/graphql/schema/field_extension.rb, line 151 def after_resolve(object:, arguments:, context:, value:, memo:) value end
Called when this extension is attached to a field. The field definition may be extended during this method. @return [void]
# File lib/graphql/schema/field_extension.rb, line 85 def apply end
Called before resolving {#field}. It should either:
-
`yield` values to continue execution; OR
-
return something else to shortcut field execution.
Whatever this method returns will be used for execution.
@param object [Object] The object the field is being resolved on @param arguments [Hash] Ruby keyword arguments for resolving this field @param context [Query::Context] the context for this query @yieldparam object [Object] The object to continue resolving the field on @yieldparam arguments [Hash] The keyword arguments to continue resolving with @yieldparam memo [Object] Any extension-specific value which will be passed to {#after_resolve} later @return [Object] The return value for this field.
# File lib/graphql/schema/field_extension.rb, line 136 def resolve(object:, arguments:, context:) yield(object, arguments, nil) end