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Contents
# frozen_string_literal: true
module GraphQL
class Schema
# - Store a table of errors & handlers
# - Rescue errors in a middleware chain, then check for a handler
# - If a handler is found, use it & return a {GraphQL::ExecutionError}
# - If no handler is found, re-raise the error
class RescueMiddleware
# @return [Hash] `{class => proc}` pairs for handling errors
attr_reader :rescue_table
def initialize
@rescue_table = {}
end
# @example Rescue from not-found by telling the user
# MySchema.rescue_from(ActiveRecord::RecordNotFound) { "An item could not be found" }
#
# @param error_class [Class] a class of error to rescue from
# @yield [err] A handler to return a message for this error instance
# @yieldparam [Exception] an error that was rescued
# @yieldreturn [String] message to put in GraphQL response
def rescue_from(error_class, &block)
rescue_table[error_class] = block
end
# Remove the handler for `error_class`
# @param error_class [Class] the error class whose handler should be removed
def remove_handler(error_class)
rescue_table.delete(error_class)
end
# Implement the requirement for {GraphQL::Schema::MiddlewareChain}
def call(*args)
begin
yield
rescue StandardError => err
attempt_rescue(err)
end
end
private
def attempt_rescue(err)
handler = rescue_table[err.class]
if handler
message = handler.call(err)
GraphQL::ExecutionError.new(message)
else
raise(err)
end
end
end
end
end
Version data entries
22 entries across 22 versions & 1 rubygems