Middleware can be inserted before or after defaults

CHANGELOG.md

@@ -5,6 +5,7 @@
 
 #### Features
 
+* [#1393](https://github.com/ruby-grape/grape/pull/1393): Middleware can be inserted before or after default Grape middleware - [@ridiculous](https://github.com/ridiculous).
 * [#1390](https://github.com/ruby-grape/grape/pull/1390): Allow inserting middleware at arbitrary points in the middleware stack - [@Rosa](https://github.com/Rosa).
 * [#1366](https://github.com/ruby-grape/grape/pull/1366): Store `message_key` on `Grape::Exceptions::Validation` - [@mkou](https://github.com/mkou).
 

lib/grape/endpoint.rb

@@ -245,42 +245,39 @@ def run
  end
 
  def build_stack
- ms = Grape::Middleware::Stack.new
-
- ms.use Rack::Head
- ms.use Grape::Middleware::Error,
- format: namespace_inheritable(:format),
- content_types: namespace_stackable_with_hash(:content_types),
- default_status: namespace_inheritable(:default_error_status),
- rescue_all: namespace_inheritable(:rescue_all),
- default_error_formatter: namespace_inheritable(:default_error_formatter),
- error_formatters: namespace_stackable_with_hash(:error_formatters),
- rescue_options: namespace_stackable_with_hash(:rescue_options) || {},
- rescue_handlers: namespace_stackable_with_hash(:rescue_handlers) || {},
- base_only_rescue_handlers: namespace_stackable_with_hash(:base_only_rescue_handlers) || {},
- all_rescue_handler: namespace_inheritable(:all_rescue_handler)
-
- ms.merge_with(namespace_stackable(:middleware) || [])
+ stack = Grape::Middleware::Stack.new
+
+ stack.use Rack::Head
+ stack.use Grape::Middleware::Error,
+  format: namespace_inheritable(:format),
+  content_types: namespace_stackable_with_hash(:content_types),
+  default_status: namespace_inheritable(:default_error_status),
+  rescue_all: namespace_inheritable(:rescue_all),
+  default_error_formatter: namespace_inheritable(:default_error_formatter),
+  error_formatters: namespace_stackable_with_hash(:error_formatters),
+  rescue_options: namespace_stackable_with_hash(:rescue_options) || {},
+  rescue_handlers: namespace_stackable_with_hash(:rescue_handlers) || {},
+  base_only_rescue_handlers: namespace_stackable_with_hash(:base_only_rescue_handlers) || {},
+  all_rescue_handler: namespace_inheritable(:all_rescue_handler)
+
+ stack.concat namespace_stackable(:middleware)
 
  if namespace_inheritable(:version)
- ms.use Grape::Middleware::Versioner.using(namespace_inheritable(:version_options)[:using]),
- versions: namespace_inheritable(:version) ? namespace_inheritable(:version).flatten : nil,
- version_options: namespace_inheritable(:version_options),
- prefix: namespace_inheritable(:root_prefix)
+ stack.use Grape::Middleware::Versioner.using(namespace_inheritable(:version_options)[:using]),
+  versions: namespace_inheritable(:version) ? namespace_inheritable(:version).flatten : nil,
+  version_options: namespace_inheritable(:version_options),
+  prefix: namespace_inheritable(:root_prefix)
  end
 
- ms.use Grape::Middleware::Formatter,
- format: namespace_inheritable(:format),
- default_format: namespace_inheritable(:default_format) || :txt,
- content_types: namespace_stackable_with_hash(:content_types),
- formatters: namespace_stackable_with_hash(:formatters),
- parsers: namespace_stackable_with_hash(:parsers)
-
- builder = Rack::Builder.new
- ms.build(builder)
+ stack.use Grape::Middleware::Formatter,
+ format: namespace_inheritable(:format),
+ default_format: namespace_inheritable(:default_format) || :txt,
+ content_types: namespace_stackable_with_hash(:content_types),
+ formatters: namespace_stackable_with_hash(:formatters),
+ parsers: namespace_stackable_with_hash(:parsers)
 
+ builder = stack.build
  builder.run ->(env) { env[Grape::Env::API_ENDPOINT].run }
-
  builder.to_app
  end
 

lib/grape/middleware/stack.rb

@@ -32,10 +32,11 @@ def inspect
 
  include Enumerable
 
- attr_accessor :middlewares
+ attr_accessor :middlewares, :others
 
  def initialize
  @middlewares = []
+ @others = []
  end
 
  def each
@@ -72,25 +73,37 @@ def use(*args, &block)
  middlewares.push(middleware)
  end
 
- def merge_with(other)
- other.each do |operation, *args|
- block = args.pop if args.last.is_a?(Proc)
- block ? send(operation, *args, &block) : send(operation, *args)
+ def merge_with(middleware_specs)
+ middleware_specs.each do |operation, *args|
+ if args.last.is_a?(Proc)
+ public_send(operation, *args, &args.pop)
+ else
+ public_send(operation, *args)
+ end
  end
  end
 
- def build(builder)
+ # @return [Rack::Builder] the builder object with our middlewares applied
+ def build(builder = Rack::Builder.new)
+ others.shift(others.size).each(&method(:merge_with))
  middlewares.each do |m|
  m.block ? builder.use(m.klass, *m.args, &m.block) : builder.use(m.klass, *m.args)
  end
+ builder
+ end
+
+ # @description Add middlewares with :use operation to the stack. Store others with :insert_* operation for later
+ # @param [Array] other_specs An array of middleware specifications (e.g. [[:use, klass], [:insert_before, *args]])
+ def concat(other_specs)
+ @others << Array(other_specs).reject { |o| o.first == :use }
+ merge_with Array(other_specs).select { |o| o.first == :use }
  end
 
  protected
 
  def assert_index(index, where)
  i = index.is_a?(Integer) ? index : middlewares.index(index)
- raise "No such middleware to insert #{where}: #{index.inspect}" unless i
- i
+ i || raise("No such middleware to insert #{where}: #{index.inspect}")
  end
  end
  end

spec/grape/middleware/stack_spec.rb

@@ -12,6 +12,9 @@ def initialize(&block)
  end
  end
 
+ let(:proc) { ->() {} }
+ let(:others) { [[:use, StackSpec::BarMiddleware], [:insert_before, StackSpec::BarMiddleware, StackSpec::BlockMiddleware, proc]] }
+
  subject { Grape::Middleware::Stack.new }
 
  before do
@@ -33,7 +36,6 @@ def initialize(&block)
  end
 
  it 'pushes a middleware class with block arguments onto the stack' do
- proc = ->() {}
  expect { subject.use StackSpec::BlockMiddleware, &proc }
  .to change { subject.size }.by(1)
  expect(subject.last).to eq(StackSpec::BlockMiddleware)
@@ -80,15 +82,42 @@ def initialize(&block)
  end
 
  describe '#merge_with' do
- let(:proc) { ->() {} }
- let(:other) { [[:use, StackSpec::BarMiddleware], [:insert_before, StackSpec::BarMiddleware, StackSpec::BlockMiddleware, proc]] }
-
  it 'applies a collection of operations and middlewares' do
- expect { subject.merge_with(other) }
+ expect { subject.merge_with(others) }
  .to change { subject.size }.by(2)
  expect(subject[0]).to eq(StackSpec::FooMiddleware)
  expect(subject[1]).to eq(StackSpec::BlockMiddleware)
  expect(subject[2]).to eq(StackSpec::BarMiddleware)
  end
  end
+
+ describe '#build' do
+ it 'returns a rack builder instance' do
+ expect(subject.build).to be_instance_of(Rack::Builder)
+ end
+
+ context 'when @others are present' do
+ let(:others) { [[:insert_after, Grape::Middleware::Formatter, StackSpec::BarMiddleware]] }
+
+ it 'applies the middleware specs stored in @others' do
+ subject.concat others
+ subject.use Grape::Middleware::Formatter
+ subject.build
+ expect(subject[0]).to eq StackSpec::FooMiddleware
+ expect(subject[1]).to eq Grape::Middleware::Formatter
+ expect(subject[2]).to eq StackSpec::BarMiddleware
+ end
+ end
+ end
+
+ describe '#concat' do
+ it 'adds non :use specs to @others' do
+ expect { subject.concat others }.to change(subject, :others).from([]).to([[others.last]])
+ end
+
+ it 'calls +merge_with+ with the :use specs' do
+ expect(subject).to receive(:merge_with).with [[:use, StackSpec::BarMiddleware]]
+ subject.concat others
+ end
+ end
 end