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# frozen_string_literal: true
module GraphQL
class Schema
module BuildFromDefinition
class ResolveMap
class DefaultResolve
def initialize(field_map, field_name)
@field_map = field_map
@field_name = field_name
end
# Make some runtime checks about
# how `obj` implements the `field_name`.
#
# Create a new resolve function according to that implementation, then:
# - update `field_map` with this implementation
# - call the implementation now (to satisfy this field execution)
#
# If `obj` doesn't implement `field_name`, raise an error.
def call(obj, args, ctx)
method_name = @field_name
if !obj.respond_to?(method_name)
raise KeyError, "Can't resolve field #{method_name} on #{obj.inspect}"
else
method_arity = obj.method(method_name).arity
resolver = case method_arity
when 0, -1
# -1 Handles method_missing, eg openstruct
->(o, a, c) { o.public_send(method_name) }
when 1
->(o, a, c) { o.public_send(method_name, a) }
when 2
->(o, a, c) { o.public_send(method_name, a, c) }
else
raise "Unexpected resolve arity: #{method_arity}. Must be 0, 1, 2"
end
# Call the resolver directly next time
@field_map[method_name] = resolver
# Call through this time
resolver.call(obj, args, ctx)
end
end
end
end
end
end
end
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