Use error collection for validation, require manual calls to validate

.rubocop_todo.yml

@@ -1,27 +1,26 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2024-09-08 11:19:50 UTC using RuboCop version 1.66.1.
+# on 2024-09-10 23:53:08 UTC using RuboCop version 1.66.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 1
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: Severity, Include.
-# Include: **/*.gemspec
-Gemspec/RequireMFA:
-  Exclude:
-    - 'lutaml-model.gemspec'
-
-# Offense count: 66
+# Offense count: 88
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: Max, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, AllowedPatterns.
 # URISchemes: http, https
 Layout/LineLength:
   Enabled: false
 
-# Offense count: 10
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowInHeredoc.
+Layout/TrailingWhitespace:
+  Exclude:
+    - 'lib/lutaml/model/schema_location.rb'
+
+# Offense count: 11
 # Configuration parameters: AllowedMethods.
 # AllowedMethods: enums
 Lint/ConstantDefinitionInBlock:
@@ -30,6 +29,7 @@ Lint/ConstantDefinitionInBlock:
     - 'spec/lutaml/model/schema/relaxng_schema_spec.rb'
     - 'spec/lutaml/model/schema/xsd_schema_spec.rb'
     - 'spec/lutaml/model/schema/yaml_schema_spec.rb'
+    - 'spec/lutaml/model/validation_spec.rb'
     - 'spec/lutaml/model/xml_adapter/xml_namespace_spec.rb'
 
 # Offense count: 1
@@ -100,7 +100,7 @@ RSpec/ContextWording:
     - 'spec/lutaml/model/xml_adapter/ox_adapter_spec.rb'
     - 'spec/lutaml/model/xml_adapter/xml_namespace_spec.rb'
 
-# Offense count: 89
+# Offense count: 101
 # Configuration parameters: CountAsOne.
 RSpec/ExampleLength:
   Max: 57
@@ -111,13 +111,14 @@ RSpec/IndexedLet:
   Exclude:
     - 'spec/address_spec.rb'
 
-# Offense count: 18
+# Offense count: 19
 RSpec/LeakyConstantDeclaration:
   Exclude:
     - 'spec/lutaml/model/schema/json_schema_spec.rb'
     - 'spec/lutaml/model/schema/relaxng_schema_spec.rb'
     - 'spec/lutaml/model/schema/xsd_schema_spec.rb'
     - 'spec/lutaml/model/schema/yaml_schema_spec.rb'
+    - 'spec/lutaml/model/validation_spec.rb'
     - 'spec/lutaml/model/xml_adapter/xml_namespace_spec.rb'
 
 # Offense count: 4
@@ -128,7 +129,7 @@ RSpec/MultipleDescribes:
     - 'spec/lutaml/model/xml_adapter/xml_namespace_spec.rb'
     - 'spec/lutaml/model/xml_adapter_spec.rb'
 
-# Offense count: 75
+# Offense count: 88
 RSpec/MultipleExpectations:
   Max: 11
 
@@ -137,10 +138,11 @@ RSpec/MultipleExpectations:
 RSpec/MultipleMemoizedHelpers:
   Max: 9
 
-# Offense count: 4
+# Offense count: 7
 RSpec/PendingWithoutReason:
   Exclude:
     - 'spec/lutaml/model/mixed_content_spec.rb'
+    - 'spec/lutaml/model/validation_spec.rb'
     - 'spec/lutaml/model/xml_adapter/oga_adapter_spec.rb'
     - 'spec/lutaml/model/xml_adapter/xml_namespace_spec.rb'
     - 'spec/lutaml/model/xml_adapter_spec.rb'
@@ -163,6 +165,11 @@ Security/CompoundHash:
   Exclude:
     - 'lib/lutaml/model/comparable_model.rb'
 
+# Offense count: 1
+Style/MissingRespondToMissing:
+  Exclude:
+    - 'lib/lutaml/model/serialize.rb'
+
 # Offense count: 1
 # Configuration parameters: AllowedMethods.
 # AllowedMethods: respond_to_missing?

README.adoc

@@ -1709,6 +1709,101 @@ In this example:
 ====
 
 
+== Validation
+
+=== General
+
+Lutaml::Model provides a way to validate data models using the `validate` and
+`validate!` methods.
+
+* The `validate` method sets an `errors` array in the model instance that
+contains all the validation errors. This method is used for checking the
+validity of the model silently.
+
+* The `validate!` method raises a `Lutaml::Model::ValidationError` that contains
+all the validation errors. This method is used for forceful validation of the
+model through raising an error.
+
+Lutaml::Model supports the following validation methods:
+
+* `collection`:: Validates collection size range.
+* `values`:: Validates the value of an attribute from a set of fixed values.
+
+[example]
+====
+The following class will validate the `degree_settings` attribute to ensure that
+it has at least one element and that the `description` attribute is one of the
+values in the set `[one, two, three]`.
+
+[source,ruby]
+----
+class Klin < Lutaml::Model::Serializable
+  attribute :name, :string
+  attribute :degree_settings, :integer, collection: (1..)
+  attribute :description, :string, values: %w[one two three]
+
+  xml do
+    map_element 'name', to: :name
+    map_attribute 'degree_settings', to: :degree_settings
+  end
+end
+
+klin = Klin.new(name: "Klin", degree_settings: [100, 200, 300], description: "one")
+klin.validate
+# => []
+
+klin = Klin.new(name: "Klin", degree_settings: [], description: "four")
+klin.validate
+# => [
+#      #<Lutaml::Model::CollectionSizeError: degree_settings must have at least 1 element>,
+#      #<Lutaml::Model::ValueError: description must be one of [one, two, three]>
+#    ]
+
+e = klin.validate!
+# => Lutaml::Model::ValidationError: [
+#      degree_settings must have at least 1 element,
+#      description must be one of [one, two, three]
+#    ]
+e.errors
+# => [
+#     #<Lutaml::Model::CollectionSizeError: degree_settings must have at least 1 element>,
+#     #<Lutaml::Model::ValueError: description must be one of [one, two, three]>
+#   ]
+----
+====
+
+=== Custom validation
+
+To add custom validation, override the `validate` method in the model class.
+Additional errors should be added to the `errors` array.
+
+[example]
+====
+The following class validates the `degree_settings` attribute when the `type` is
+`glass` to ensure that the value is less than 1300.
+
+[source,ruby]
+----
+class Klin < Lutaml::Model::Serializable
+  attribute :name, :string
+  attribute :type, :string, values: %w[glass ceramic]
+  attribute :degree_settings, :integer, collection: (1..)
+
+  def validate
+    errors = super
+    if type == "glass" && degree_settings.any? { |d| d > 1300 }
+      errors << Lutaml::Model::Error.new("Degree settings for glass must be less than 1300")
+    end
+  end
+end
+
+klin = Klin.new(name: "Klin", type: "glass", degree_settings: [100, 200, 1400])
+klin.validate
+# => [#<Lutaml::Model::Error: Degree settings for glass must be less than 1300>]
+----
+====
+
+
 == Adapters
 
 === General

lib/lutaml/model/attribute.rb

@@ -60,35 +60,25 @@ def enum_values
       #      e.g if collection: 0..5 is set then the value greater then 5
       #          will raise `Lutaml::Model::CollectionCountOutOfRangeError`
       def validate_value!(value)
-        # return true if none of the validations are present
-        return true if enum_values.empty? && singular?
-
-        # Use the default value if the value is nil
-        value = default if value.nil?
-
-        valid_value!(value) && valid_collection!(value)
-      end
-
-      def valid_value?(value)
-        return true unless options[:values]
-
-        options[:values].include?(value)
+        valid_value!(value)
+        valid_collection!(value)
       end
 
       def valid_value!(value)
+        return true if value.nil? && !collection?
+        return true if enum_values.empty?
+
         unless valid_value?(value)
           raise Lutaml::Model::InvalidValueError.new(name, value, enum_values)
         end
 
         true
       end
 
-      def valid_collection?(value)
-        return true unless collection?
-        return false unless value.is_a?(Array)
-        return collection? if [true, false].include?(options[:collection])
+      def valid_value?(value)
+        return true unless options[:values]
 
-        options[:collection].include?(value.count)
+        options[:values].include?(value)
       end
 
       def validate_value!(value)
@@ -127,7 +117,12 @@ def validate_collection_range
 
       def valid_collection!(value)
         return true unless collection?
-        return true if value.nil? # Allow nil values for collections during initialization
+
+        # Allow nil values for collections during initialization
+        return true if value.nil?
+
+        # Allow any value for unbounded collections
+        return true if options[:collection] == true
 
         unless value.is_a?(Array)
           raise Lutaml::Model::CollectionCountOutOfRangeError.new(
@@ -138,28 +133,23 @@ def valid_collection!(value)
         end
 
         range = options[:collection]
-        if range.is_a?(Range)
-          if range.end.nil?
-            if value.size < range.begin
-              raise Lutaml::Model::CollectionCountOutOfRangeError.new(
-                name,
-                value,
-                range,
-              )
-            end
-          elsif !range.cover?(value.size)
+        return true unless range.is_a?(Range)
+
+        if range.end.nil?
+          if value.size < range.begin
             raise Lutaml::Model::CollectionCountOutOfRangeError.new(
               name,
               value,
               range,
             )
           end
-        elsif range == true && value.empty?
-          # Allow empty arrays for unbounded collections
-          return true
+        elsif !range.cover?(value.size)
+          raise Lutaml::Model::CollectionCountOutOfRangeError.new(
+            name,
+            value,
+            range,
+          )
         end
-
-        true
       end
 
       def serialize(value, format, options = {})

lib/lutaml/model/error.rb

@@ -8,3 +8,4 @@ class Error < StandardError
 require_relative "error/invalid_value_error"
 require_relative "error/unknown_adapter_type_error"
 require_relative "error/collection_count_out_of_range_error"
+require_relative "error/validation_error"

lib/lutaml/model/error/validation_error.rb

@@ -0,0 +1,21 @@
+# lib/lutaml/model/error/validation_error.rb
+module Lutaml
+  module Model
+    class ValidationError < Error
+      attr_reader :errors
+
+      def initialize(errors)
+        @errors = errors
+        super(errors.join(", "))
+      end
+
+      def include?(error_class)
+        errors.any?(error_class)
+      end
+
+      def error_messages
+        errors.map(&:message)
+      end
+    end
+  end
+end

lib/lutaml/model/schema_location.rb

@@ -18,7 +18,8 @@ class SchemaLocation
 
       attr_reader :namespace, :prefix, :schema_location
 
-      def initialize(schema_location:, prefix: "xsi", namespace: DEFAULT_NAMESPACE)
+      def initialize(schema_location:, prefix: "xsi",
+namespace: DEFAULT_NAMESPACE)
         @original_schema_location = schema_location
         @schema_location = parsed_schema_locations(schema_location)
         @prefix = prefix