Deep Merge for group parameter attributes

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 #### Features
 
+* [#2432](https://github.com/ruby-grape/grape/pull/2432): Deep merge for group parameter attributes - [@numbata](https://github.com/numbata).
 * [#2419](https://github.com/ruby-grape/grape/pull/2419): Add the `contract` DSL - [@dgutov](https://github.com/dgutov).
 * [#2371](https://github.com/ruby-grape/grape/pull/2371): Use a param value as the `default` value of other param - [@jcagarcia](https://github.com/jcagarcia).
 * [#2377](https://github.com/ruby-grape/grape/pull/2377): Allow to use instance variables values inside `rescue_from` - [@jcagarcia](https://github.com/jcagarcia).

README.md

@@ -1542,23 +1542,26 @@ Note: param in `given` should be the renamed one. In the example, it should be `
 
 ### Group Options
 
-Parameters options can be grouped. It can be useful if you want to extract common validation or types for several parameters. The example below presents a typical case when parameters share common options.
+Parameters options can be grouped. It can be useful if you want to extract common validation or types for several parameters.
+Within these groups, individual parameters can extend or selectively override the common settings, allowing you to maintain the defaults at the group level while still applying parameter-specific rules where necessary.
+
+The example below presents a typical case when parameters share common options.
 
 ```ruby
 params do
-  requires :first_name, type: String, regexp: /w+/, desc: 'First name'
-  requires :middle_name, type: String, regexp: /w+/, desc: 'Middle name'
-  requires :last_name, type: String, regexp: /w+/, desc: 'Last name'
+  requires :first_name, type: String, regexp: /w+/, desc: 'First name', documentation: { in: 'body' }
+  optional :middle_name, type: String, regexp: /w+/, desc: 'Middle name', documentation: { in: 'body', x: { nullable: true } }
+  requires :last_name, type: String, regexp: /w+/, desc: 'Last name', documentation: { in: 'body' }
 end
 ```
 
 Grape allows you to present the same logic through the `with` method in your parameters block, like so:
 
 ```ruby
 params do
-  with(type: String, regexp: /w+/) do
+  with(type: String, regexp: /w+/, documentation: { in: 'body' }) do
     requires :first_name, desc: 'First name'
-    requires :middle_name, desc: 'Middle name'
+    optional :middle_name, desc: 'Middle name', documentation: { x: { nullable: true } }
     requires :last_name, desc: 'Last name'
   end
 end

UPGRADING.md

@@ -3,6 +3,33 @@ Upgrading Grape
 
 ### Upgrading to >= 2.1.0
 
+#### Deep Merging of Parameter Attributes
+
+Grape now uses `deep_merge` to combine parameter attributes within the `with` method. Previously, attributes defined at the parameter level would override those defined at the group level.
+With deep merge, attributes are now combined, allowing for more detailed and nuanced API specifications.
+
+For example:
+
+```ruby
+with(documentation: { in: 'body' }) do
+  optional :vault, documentation: { default: 33 }
+end
+```
+
+Before it was equivalent to:
+
+```ruby
+optional :vault, documentation: { default: 33 }
+```
+
+After it is an equivalent of:
+
+```ruby
+optional :vault, documentation: { in: 'body', default: 33 }
+```
+
+See [#2432](https://github.com/ruby-grape/grape/pull/2432) for more information.
+
 #### Zeitwerk
 
 Grape's autoloader has been updated and it's now based on [Zeitwerk](https://github.com/fxn/zeitwerk).
@@ -179,7 +206,7 @@ If you are using Rack 3 in your application then the headers will be set to:
 { "content-type" => "application/json", "secret-password" => "foo"}
 ```
 
-This means if you are checking for header values in your application, you would need to change your code to use downcased keys. 
+This means if you are checking for header values in your application, you would need to change your code to use downcased keys.
 
 ```ruby
 get do

lib/grape/dsl/parameters.rb

@@ -130,7 +130,7 @@ def requires(*attrs, &block)
 
         opts = attrs.extract_options!.clone
         opts[:presence] = { value: true, message: opts[:message] }
-        opts = @group.merge(opts) if instance_variable_defined?(:@group) && @group
+        opts = @group.deep_merge(opts) if instance_variable_defined?(:@group) && @group
 
         if opts[:using]
           require_required_and_optional_fields(attrs.first, opts)
@@ -149,7 +149,7 @@ def optional(*attrs, &block)
 
         opts = attrs.extract_options!.clone
         type = opts[:type]
-        opts = @group.merge(opts) if instance_variable_defined?(:@group) && @group
+        opts = @group.deep_merge(opts) if instance_variable_defined?(:@group) && @group
 
         # check type for optional parameter group
         if attrs && block

spec/grape/dsl/parameters_spec.rb

@@ -7,8 +7,12 @@ class Dummy
         include Grape::DSL::Parameters
         attr_accessor :api, :element, :parent
 
+        def initialize
+          @validate_attributes = []
+        end
+
         def validate_attributes(*args)
-          @validate_attributes = *args
+          @validate_attributes.push(*args)
         end
 
         def validate_attributes_reader
@@ -106,6 +110,65 @@ def extract_message_option(attrs)
           expect(subject.validate_attributes_reader).to eq([[:id], { type: Integer, desc: 'Identity.' }])
           expect(subject.push_declared_params_reader).to eq([:id])
         end
+
+        it 'merges the group attributes' do
+          subject.with(documentation: { in: 'body' }) { subject.optional :vault, documentation: { default: 33 } }
+
+          expect(subject.validate_attributes_reader).to eq([[:vault], { documentation: { in: 'body', default: 33 } }])
+          expect(subject.push_declared_params_reader).to eq([:vault])
+        end
+
+        it 'overrides the group attribute when values not mergable' do
+          subject.with(type: Integer, documentation: { in: 'body', default: 33 }) do
+            subject.optional :vault
+            subject.optional :allowed_vaults, type: [Integer], documentation: { default: [31, 32, 33], is_array: true }
+          end
+
+          expect(subject.validate_attributes_reader).to eq(
+            [
+              [:vault], { type: Integer, documentation: { in: 'body', default: 33 } },
+              [:allowed_vaults], { type: [Integer], documentation: { in: 'body', default: [31, 32, 33], is_array: true } }
+            ]
+          )
+        end
+
+        it 'allows a primitive type attribite to overwrite a complex type group attribute' do
+          subject.with(documentation: { x: { nullable: true } }) do
+            subject.optional :vault, type: Integer, documentation: { x: nil }
+          end
+
+          expect(subject.validate_attributes_reader).to eq(
+            [
+              [:vault], { type: Integer, documentation: { x: nil } }
+            ]
+          )
+        end
+
+        it 'does not nest primitives inside existing complex types erroneously' do
+          subject.with(type: Hash, documentation: { default: { vault: '33' } }) do
+            subject.optional :info
+            subject.optional :role, type: String, documentation: { default: 'resident' }
+          end
+
+          expect(subject.validate_attributes_reader).to eq(
+            [
+              [:info], { type: Hash, documentation: { default: { vault: '33' } } },
+              [:role], { type: String, documentation: { default: 'resident' } }
+            ]
+          )
+        end
+
+        it 'merges deeply nested attributes' do
+          subject.with(documentation: { details: { in: 'body', hidden: false } }) do
+            subject.optional :vault, documentation: { details: { desc: 'The vault number' } }
+          end
+
+          expect(subject.validate_attributes_reader).to eq(
+            [
+              [:vault], { documentation: { details: { in: 'body', hidden: false, desc: 'The vault number' } } }
+            ]
+          )
+        end
       end
 
       describe '#mutually_exclusive' do