diff --git a/packages/forest_admin_agent/lib/forest_admin_agent/routes/capabilities/collections.rb b/packages/forest_admin_agent/lib/forest_admin_agent/routes/capabilities/collections.rb
index 8c88ab67e..db847e196 100644
--- a/packages/forest_admin_agent/lib/forest_admin_agent/routes/capabilities/collections.rb
+++ b/packages/forest_admin_agent/lib/forest_admin_agent/routes/capabilities/collections.rb
@@ -24,11 +24,13 @@ def handle_request(args = {})
             collection = datasource.get_collection(collection_name)
             {
               name: collection.name,
-              fields: collection.schema[:fields].select { |_, field| field.is_a?(ColumnSchema) }.map do |name, field|
+              fields: collection.schema[:fields].filter_map do |name, field|
+                next unless field.is_a?(ColumnSchema)
+
                 {
                   name: name,
                   type: field.column_type,
-                  operators: field.filter_operators.map { |operator| operator }
+                  operators: field.filter_operators.to_a
                 }
               end
             }
diff --git a/packages/forest_admin_agent/lib/forest_admin_agent/serializer/forest_serializer.rb b/packages/forest_admin_agent/lib/forest_admin_agent/serializer/forest_serializer.rb
index 348e9714b..0f2ba7d0d 100644
--- a/packages/forest_admin_agent/lib/forest_admin_agent/serializer/forest_serializer.rb
+++ b/packages/forest_admin_agent/lib/forest_admin_agent/serializer/forest_serializer.rb
@@ -29,10 +29,7 @@ def id
           @options[:class_name].gsub('::', '__')
         )
         primary_keys = ForestAdminDatasourceToolkit::Utils::Schema.primary_keys(forest_collection)
-        id = []
-        primary_keys.each { |key| id << @object[key] }
-
-        id.join('|')
+        primary_keys.map { |key| @object[key] }.join('|')
       end
 
       def format_name(attribute_name)
diff --git a/packages/forest_admin_agent/lib/forest_admin_agent/services/permissions.rb b/packages/forest_admin_agent/lib/forest_admin_agent/services/permissions.rb
index c497425db..8db0dcc32 100644
--- a/packages/forest_admin_agent/lib/forest_admin_agent/services/permissions.rb
+++ b/packages/forest_admin_agent/lib/forest_admin_agent/services/permissions.rb
@@ -263,7 +263,7 @@ def permission_system?
       def find_action_from_endpoint(collection_name, path, http_method)
         endpoint = path.partition('/forest/')[1..].join
         schema_file = JSON.parse(File.read(Facades::Container.config_from_cache[:schema_path]))
-        actions = schema_file['collections']&.select { |collection| collection['name'] == collection_name }&.first&.dig('actions')
+        actions = schema_file['collections']&.find { |collection| collection['name'] == collection_name }&.dig('actions')
 
         return nil if actions.nil? || actions.empty?
 
diff --git a/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/column.rb b/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/column.rb
index 5723c7c57..59e578d2a 100644
--- a/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/column.rb
+++ b/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/column.rb
@@ -43,15 +43,13 @@ def get_column_type(model, column)
       end
 
       def get_enum_values(model, column)
-        enum_values = []
-        if get_column_type(model, column) == 'Enum'
-          if sti_column?(model, column)
-            model.descendants.each { |sti_model| enum_values << sti_model.name }
-          else
-            model.defined_enums[column.name].each_key { |name| enum_values << name }
-          end
+        return [] unless get_column_type(model, column) == 'Enum'
+
+        if sti_column?(model, column)
+          model.descendants.map(&:name)
+        else
+          model.defined_enums[column.name].keys
         end
-        enum_values
       end
 
       def sti_column?(model, column)
diff --git a/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/validation.rb b/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/validation.rb
index e59e472bd..27b3b15b1 100644
--- a/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/validation.rb
+++ b/packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/parser/validation.rb
@@ -6,7 +6,7 @@ def get_validations(column)
         validations = []
         # NOTICE: Do not consider validations if a before_validation Active Records
         #         Callback is detected.
-        return validations if @model._validation_callbacks.map(&:kind).include? :before
+        return validations if @model._validation_callbacks.any? { |callback| callback.kind == :before }
 
         if @model._validators? && @model._validators[column.name.to_sym].size.positive?
           @model._validators[column.name.to_sym].each do |validator|
diff --git a/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/composite_datasource.rb b/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/composite_datasource.rb
index 6a42802c8..053e73663 100644
--- a/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/composite_datasource.rb
+++ b/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/composite_datasource.rb
@@ -52,10 +52,9 @@ def execute_native_query(connection_name, query, context_variables = {})
     end
 
     def add_data_source(datasource)
-      existing_names = collections.map { |c| c.respond_to?(:name) ? c.name : c.to_s }
-      datasource.collections.each do |c|
-        new_name = c.respond_to?(:name) ? c.name : c.to_s
-        raise ArgumentError, "Collection '#{new_name}' already exists" if existing_names.include?(new_name)
+      existing_names = collections.keys
+      datasource.collections.each_key do |name|
+        raise ArgumentError, "Collection '#{name}' already exists" if existing_names.include?(name)
       end
 
       existing_charts = schema[:charts]
diff --git a/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/computed/utils/flattener.rb b/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/computed/utils/flattener.rb
index add0941ee..0c182b2b0 100644
--- a/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/computed/utils/flattener.rb
+++ b/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/computed/utils/flattener.rb
@@ -17,16 +17,22 @@ def dig(*_keys)
 
           MARKER_NAME = '__null_marker'.freeze
           def self.with_null_marker(projection)
+            seen = Set.new(projection)
             new_projection = Projection.new(projection)
+
             projection.each do |path|
               parts = path.split(':')
 
               parts.slice(1, parts.size).each_with_index do |_item, index|
-                new_projection << "#{parts.slice(0, index + 1).join(":")}:#{MARKER_NAME}"
+                marker = "#{parts.slice(0, index + 1).join(":")}:#{MARKER_NAME}"
+                next if seen.include?(marker)
+
+                seen << marker
+                new_projection << marker
               end
             end
 
-            new_projection.uniq
+            new_projection
           end
 
           def self.flatten(records, projection)
diff --git a/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/relation/relation_collection_decorator.rb b/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/relation/relation_collection_decorator.rb
index 8fe979dd5..918583d0f 100644
--- a/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/relation/relation_collection_decorator.rb
+++ b/packages/forest_admin_datasource_customizer/lib/forest_admin_datasource_customizer/decorators/relation/relation_collection_decorator.rb
@@ -240,31 +240,37 @@ def re_project_in_place(caller, records, projection)
 
         def re_project_relation_in_place(caller, records, name, projection)
           field_schema = schema[:fields][name]
-
           return if field_schema.type == 'PolymorphicManyToOne'
 
-          association = datasource.get_collection(field_schema.foreign_collection)
-
           if !@relations[name]
+            association = datasource.get_collection(field_schema.foreign_collection)
             association.re_project_in_place(caller, records.filter_map { |r| r[name] }, projection)
           elsif field_schema.type == 'ManyToOne'
-            ids = records.filter_map { |record| record[field_schema.foreign_key] }.uniq
-            sub_filter = Filter.new(condition_tree: ConditionTreeLeaf.new(field_schema.foreign_key_target, 'In', ids))
-            sub_records = association.list(caller, sub_filter, projection.union([field_schema.foreign_key_target]))
-
-            records.each do |record|
-              record[name] = sub_records.find { |sr| sr[field_schema.foreign_key_target] == record[field_schema.foreign_key] }
-            end
+            assign_many_to_one_records(caller, records, name, field_schema, projection)
           elsif ['OneToOne', 'OneToMany'].include?(field_schema.type)
-            ids = records.filter_map { |record| record[field_schema.origin_key_target] }.uniq
-            sub_filter = Filter.new(condition_tree: ConditionTreeLeaf.new(field_schema.origin_key, 'In', ids))
-            sub_records = association.list(caller, sub_filter, projection.union([field_schema.origin_key]))
-
-            records.each do |record|
-              record[name] = sub_records.find { |sr| sr[field_schema.origin_key] == record[field_schema.origin_key_target] }
-            end
+            assign_to_one_or_many_records(caller, records, name, field_schema, projection)
           end
         end
+
+        def assign_many_to_one_records(caller, records, name, field_schema, projection)
+          association = datasource.get_collection(field_schema.foreign_collection)
+          ids = records.each_with_object(Set.new) { |record, set| set << record[field_schema.foreign_key] }.delete(nil).to_a
+          sub_filter = Filter.new(condition_tree: ConditionTreeLeaf.new(field_schema.foreign_key_target, 'In', ids))
+          sub_records = association.list(caller, sub_filter, projection.union([field_schema.foreign_key_target]))
+          sub_records_by_key = sub_records.to_h { |sr| [sr[field_schema.foreign_key_target], sr] }
+
+          records.each { |record| record[name] = sub_records_by_key[record[field_schema.foreign_key]] }
+        end
+
+        def assign_to_one_or_many_records(caller, records, name, field_schema, projection)
+          association = datasource.get_collection(field_schema.foreign_collection)
+          ids = records.each_with_object(Set.new) { |record, set| set << record[field_schema.origin_key_target] }.delete(nil).to_a
+          sub_filter = Filter.new(condition_tree: ConditionTreeLeaf.new(field_schema.origin_key, 'In', ids))
+          sub_records = association.list(caller, sub_filter, projection.union([field_schema.origin_key]))
+          sub_records_by_key = sub_records.to_h { |sr| [sr[field_schema.origin_key], sr] }
+
+          records.each { |record| record[name] = sub_records_by_key[record[field_schema.origin_key_target]] }
+        end
       end
     end
   end
diff --git a/packages/forest_admin_datasource_customizer/spec/lib/forest_admin_datasource_customizer/datasource_customizer_spec.rb b/packages/forest_admin_datasource_customizer/spec/lib/forest_admin_datasource_customizer/datasource_customizer_spec.rb
index f9623b2b8..d91299183 100644
--- a/packages/forest_admin_datasource_customizer/spec/lib/forest_admin_datasource_customizer/datasource_customizer_spec.rb
+++ b/packages/forest_admin_datasource_customizer/spec/lib/forest_admin_datasource_customizer/datasource_customizer_spec.rb
@@ -161,7 +161,7 @@ def schema
       datasource = instance_double(ForestAdminDatasourceToolkit::Datasource,
                                    schema: { charts: [] },
                                    render_chart: nil,
-                                   collections: [],
+                                   collections: {},
                                    live_query_connections: {})
 
       customizer = described_class.new
diff --git a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/relation.rb b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/relation.rb
index 75ea689fa..3c33341f0 100644
--- a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/relation.rb
+++ b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/relation.rb
@@ -4,10 +4,12 @@ module Relation
       def get_polymorphic_types(relation_name)
         types = {}
 
-        ObjectSpace.each_object(Class).select { |klass| klass < Mongoid::Document }.each do |model|
-          if model.relations.any? { |_, relation| relation.options[:as] == relation_name.to_sym }
-            primary_key = model.fields.keys.find { |key| model.fields[key].options[:as] == :id } || :_id
-            types[model.name.gsub('::', '__')] = primary_key.to_s
+        ObjectSpace.each_object(Class).each do |klass|
+          next unless klass < Mongoid::Document
+
+          if klass.relations.any? { |_, relation| relation.options[:as] == relation_name.to_sym }
+            primary_key = klass.fields.keys.find { |key| klass.fields[key].options[:as] == :id } || :_id
+            types[klass.name.gsub('::', '__')] = primary_key.to_s
           end
         end
 
diff --git a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/validation.rb b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/validation.rb
index 10e3aa302..81203fd45 100644
--- a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/validation.rb
+++ b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/parser/validation.rb
@@ -4,33 +4,35 @@ module Validation
       include ForestAdminDatasourceToolkit::Components::Query::ConditionTree
       def get_validations(model, column)
         return [] if column.is_a?(Hash)
+        return [] if before_validation_callback?(model)
+        return [] unless model._validators? && model._validators[column.name.to_sym].size.positive?
 
-        validations = []
-        # NOTICE: Do not consider validations if a before_validation Active Records
-        #         Callback is detected.
+        parse_column_validators(model._validators[column.name.to_sym], column)
+      end
+
+      def before_validation_callback?(model)
         default_callback_excluded = [:normalize_changed_in_place_attributes]
-        return validations if model._validation_callbacks
-                                   .reject { |callback| default_callback_excluded.include?(callback.filter) }
-                                   .map(&:kind).include?(:before)
+        model._validation_callbacks.any? do |callback|
+          !default_callback_excluded.include?(callback.filter) && callback.kind == :before
+        end
+      end
 
-        if model._validators? && model._validators[column.name.to_sym].size.positive?
-          model._validators[column.name.to_sym].each do |validator|
-            # NOTICE: Do not consider conditional validations
-            next if validator.options[:if] || validator.options[:unless] || validator.options[:on]
+      def parse_column_validators(validators, column)
+        validations = []
+        validators.each do |validator|
+          next if validator.options[:if] || validator.options[:unless] || validator.options[:on]
 
-            case validator.class.to_s
-            when Mongoid::Validatable::PresenceValidator.to_s
-              validations << { operator: Operators::PRESENT }
-            when ActiveModel::Validations::NumericalityValidator.to_s
-              validations = parse_numericality_validator(validator, validations)
-            when Mongoid::Validatable::LengthValidator.to_s
-              validations = parse_length_validator(validator, validations, column)
-            when Mongoid::Validatable::FormatValidator.to_s
-              validations = parse_format_validator(validator, validations)
-            end
+          case validator.class.to_s
+          when Mongoid::Validatable::PresenceValidator.to_s
+            validations << { operator: Operators::PRESENT }
+          when ActiveModel::Validations::NumericalityValidator.to_s
+            validations = parse_numericality_validator(validator, validations)
+          when Mongoid::Validatable::LengthValidator.to_s
+            validations = parse_length_validator(validator, validations, column)
+          when Mongoid::Validatable::FormatValidator.to_s
+            validations = parse_format_validator(validator, validations)
           end
         end
-
         validations
       end
 
diff --git a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/add_null_values.rb b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/add_null_values.rb
index 878e0dade..8bf5244d9 100644
--- a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/add_null_values.rb
+++ b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/add_null_values.rb
@@ -28,11 +28,13 @@ def add_null_values_on_record(record, projection)
           result[field_prefix] ||= nil
         end
 
-        nested_prefixes = projection.select { |field| field.include?(':') }.map { |field| field.split(':').first }.uniq
+        nested_prefixes = projection.filter_map { |field| field.split(':').first if field.include?(':') }.uniq
 
         nested_prefixes.each do |nested_prefix|
-          child_paths = projection.filter { |field| field.start_with?("#{nested_prefix}:") }
-                                  .map { |field| field[(nested_prefix.size + 1)..] }
+          prefix_with_colon = "#{nested_prefix}:"
+          child_paths = projection.filter_map do |field|
+            field[(nested_prefix.size + 1)..] if field.start_with?(prefix_with_colon)
+          end
 
           next unless result[nested_prefix] && !result[nested_prefix].nil?
 
diff --git a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/helpers.rb b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/helpers.rb
index 2b9043049..779c1e70e 100644
--- a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/helpers.rb
+++ b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/helpers.rb
@@ -5,7 +5,8 @@ module Helpers
       # @example
       # unnest(['firstname', 'book.title', 'book.author'], 'book') == ['title', 'author']
       def unnest(strings, prefix)
-        strings.select { |field| field.start_with?("#{prefix}.") }.map { |field| field[(prefix.size + 1)..] }
+        prefix_with_dot = "#{prefix}."
+        strings.filter_map { |field| field[(prefix.size + 1)..] if field.start_with?(prefix_with_dot) }
       end
 
       def escape(str)
diff --git a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/filter_generator.rb b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/filter_generator.rb
index 171306ca1..649942b33 100644
--- a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/filter_generator.rb
+++ b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/filter_generator.rb
@@ -76,7 +76,7 @@ def self.list_fields_used_in_filter_tree(condition_tree, fields)
           if condition_tree.is_a? Nodes::ConditionTreeBranch
             condition_tree.conditions.each { |condition| list_fields_used_in_filter_tree(condition, fields) }
           elsif condition_tree&.field&.include?(':')
-            list_paths(condition_tree.field).each { |field| fields << field }
+            fields.merge(list_paths(condition_tree.field))
           end
         end
 
diff --git a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/lookup_generator.rb b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/lookup_generator.rb
index be9620643..d5db7390b 100644
--- a/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/lookup_generator.rb
+++ b/packages/forest_admin_datasource_mongoid/lib/forest_admin_datasource_mongoid/utils/pipeline/lookup_generator.rb
@@ -35,23 +35,25 @@ def self.add_fields(name, projection, options)
           return {} if options[:include] && !options[:include].include?(name)
           return {} if options[:exclude]&.include?(name)
 
-          projection.filter { |field| field.include?('@@@') }
-                    .map { |field_name| "#{name}.#{field_name.tr(":", ".")}" }
-                    .each_with_object({}) do |curr, acc|
-                      acc[curr] = "$#{curr.gsub("@@@", ".")}"
-                    end
+          projection.each_with_object({}) do |field_name, acc|
+            next unless field_name.include?('@@@')
+
+            curr = "#{name}.#{field_name.tr(":", ".")}"
+            acc[curr] = "$#{curr.gsub("@@@", ".")}"
+          end
         end
 
         def self.lookup_relation(current_path, schema_stack, name, projection, options)
-          models = ObjectSpace
-                   .each_object(Class)
-                   .select { |klass| klass < Mongoid::Document && klass.name && !klass.name.start_with?('Mongoid::') }
-                   .to_h { |klass| [klass.name, klass] }
+          models = ObjectSpace.each_object(Class).with_object({}) do |klass, hash|
+            next unless klass < Mongoid::Document && klass.name && !klass.name.start_with?('Mongoid::')
+
+            hash[klass.name] = klass
+          end
 
           as = current_path ? "#{current_path}.#{name}" : name
 
-          last_schema = schema_stack[schema_stack.length - 1]
-          previous_schema = schema_stack.slice(0..(schema_stack.length - 1))
+          last_schema = schema_stack.last
+          previous_schema = schema_stack
 
           return {} if options[:include] && !options[:include].include?(as)
           return {} if options[:exclude]&.include?(as)
diff --git a/packages/forest_admin_datasource_mongoid/spec/spec_helper.rb b/packages/forest_admin_datasource_mongoid/spec/spec_helper.rb
index d22ba39b3..830b194fe 100644
--- a/packages/forest_admin_datasource_mongoid/spec/spec_helper.rb
+++ b/packages/forest_admin_datasource_mongoid/spec/spec_helper.rb
@@ -32,7 +32,7 @@
     models_to_load = Dir.glob(File.join('spec', 'dummy', 'app', 'models', '**', '*.rb'))
                         .collect { |file_path| File.basename(file_path, '.rb').camelize.constantize }
 
-    allow(ObjectSpace).to receive(:each_object).and_return(models_to_load)
+    allow(ObjectSpace).to receive(:each_object).and_return(models_to_load.each)
   end
 
   config.before(:suite) do