More efficient access when DTOs are used in template models.

org.jdrupes.vmoperator.util/.settings/org.eclipse.jdt.core.prefs

@@ -1,5 +1,5 @@
 #
-#Tue May 23 17:52:06 CEST 2023
+#Sun May 28 16:23:45 CEST 2023
 org.eclipse.jdt.core.formatter.insert_space_before_comma_in_for_inits=do not insert
 org.eclipse.jdt.core.formatter.brace_position_for_block=end_of_line
 org.eclipse.jdt.core.formatter.insert_space_after_at_in_annotation_type_declaration=do not insert
@@ -286,9 +286,9 @@ org.eclipse.jdt.core.formatter.continuation_indentation_for_array_initializer=1
 org.eclipse.jdt.core.formatter.parentheses_positions_in_switch_statement=common_lines
 org.eclipse.jdt.core.formatter.lineSplit=80
 org.eclipse.jdt.core.compiler.source=17
-org.eclipse.jdt.core.formatter.insert_new_line_in_empty_anonymous_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_new_line_in_empty_method_body=insert
 org.eclipse.jdt.core.formatter.tabulation.size=4
+org.eclipse.jdt.core.formatter.insert_new_line_in_empty_method_body=insert
+org.eclipse.jdt.core.formatter.insert_new_line_in_empty_anonymous_type_declaration=insert
 org.eclipse.jdt.core.formatter.comment.count_line_length_from_starting_position=false
 org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
 org.eclipse.jdt.core.formatter.brace_position_for_array_initializer=end_of_line
@@ -304,13 +304,13 @@ org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_constructor_
 org.eclipse.jdt.core.formatter.insert_space_after_opening_angle_bracket_in_parameterized_type_reference=do not insert
 org.eclipse.jdt.core.formatter.indent_statements_compare_to_block=true
 org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_catch=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_cast=do not insert
 org.eclipse.jdt.core.formatter.insert_space_before_comma_in_type_arguments=do not insert
+org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_cast=do not insert
 org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_annotation=do not insert
-eclipse.preferences.version=1
 org.eclipse.jdt.core.formatter.brace_position_for_lambda_body=end_of_line
-org.eclipse.jdt.core.formatter.insert_space_before_closing_bracket_in_array_reference=do not insert
+eclipse.preferences.version=1
 org.eclipse.jdt.core.formatter.enabling_tag=@formatter\:on
+org.eclipse.jdt.core.formatter.insert_space_before_closing_bracket_in_array_reference=do not insert
 org.eclipse.jdt.core.compiler.compliance=17
 org.eclipse.jdt.core.formatter.blank_lines_after_package=1
 org.eclipse.jdt.core.formatter.alignment_for_superinterfaces_in_type_declaration=16

org.jdrupes.vmoperator.util/build.gradle

@@ -9,6 +9,5 @@ plugins {
 }
 
 dependencies {
-    implementation 'com.fasterxml.jackson.core:jackson-databind:[2.15.0,3]'
     implementation 'org.freemarker:freemarker:[2.3.32,2.4)'
 }

org.jdrupes.vmoperator.util/src/org/jdrupes/vmoperator/util/Dto.java

@@ -18,6 +18,15 @@
 
 package org.jdrupes.vmoperator.util;
 
+/**
+ * Marks a class as the definition of a data transfer object.
+ * DTOs have public attributes and usually no behavior (though
+ * the can have e.g. methods for checking the consistency.
+ * 
+ * The DTO marker affects the conversion of objects to other
+ * representations.
+ */
+@SuppressWarnings("PMD.ShortClassName")
 public interface Dto {
 
 }

org.jdrupes.vmoperator.util/src/org/jdrupes/vmoperator/util/DtoTemplateModel.java

@@ -0,0 +1,72 @@
+/*
+ * VM-Operator
+ * Copyright (C) 2023 Michael N. Lipp
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.jdrupes.vmoperator.util;
+
+import freemarker.ext.util.WrapperTemplateModel;
+import freemarker.template.ObjectWrapper;
+import freemarker.template.TemplateHashModel;
+import freemarker.template.TemplateModel;
+import freemarker.template.TemplateModelException;
+import freemarker.template.WrappingTemplateModel;
+
+/**
+ * Wraps a DTO in a {@link TemplateHashModel}.
+ */
+public class DtoTemplateModel extends WrappingTemplateModel
+        implements WrapperTemplateModel, TemplateHashModel {
+
+    private final Dto dto;
+
+    /**
+     * Instantiates a new DTO template model.
+     *
+     * @param objectWrapper the object wrapper
+     * @param dto the dto
+     */
+    public DtoTemplateModel(ObjectWrapper objectWrapper, Dto dto) {
+        super(objectWrapper);
+        this.dto = dto;
+    }
+
+    @Override
+    @SuppressWarnings("PMD.PreserveStackTrace")
+    public TemplateModel get(String key) throws TemplateModelException {
+        try {
+            var field = dto.getClass().getDeclaredField(key);
+            return wrap(field.get(dto));
+        } catch (NoSuchFieldException | SecurityException e) {
+            throw new TemplateModelException("No Field " + key
+                + " in class " + dto.getClass());
+        } catch (IllegalArgumentException | IllegalAccessException e) {
+            throw new TemplateModelException("Cannot access field " + key
+                + " in class " + dto.getClass());
+        }
+    }
+
+    @Override
+    public boolean isEmpty() throws TemplateModelException {
+        return false;
+    }
+
+    @Override
+    public Object getWrappedObject() {
+        return dto;
+    }
+
+}

org.jdrupes.vmoperator.util/src/org/jdrupes/vmoperator/util/ExtendedObjectWrapper.java

@@ -18,31 +18,31 @@
 
 package org.jdrupes.vmoperator.util;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
 import freemarker.template.DefaultObjectWrapper;
 import freemarker.template.TemplateModel;
 import freemarker.template.TemplateModelException;
 import freemarker.template.Version;
-import java.util.Map;
 
+/**
+ * Provides an object wrapper that handles {@link Dto}s.
+ */
 public class ExtendedObjectWrapper extends DefaultObjectWrapper {
 
-    private ObjectMapper mapper;
-
-    public ExtendedObjectWrapper(Version incompatibleImprovements,
-            ObjectMapper mapper) {
+    /**
+     * Instantiates a new extended object wrapper.
+     *
+     * @param incompatibleImprovements the incompatible improvements
+     */
+    public ExtendedObjectWrapper(Version incompatibleImprovements) {
         super(incompatibleImprovements);
-        this.mapper = mapper;
     }
 
     @Override
     protected TemplateModel handleUnknownType(final Object obj)
             throws TemplateModelException {
-        if (obj instanceof Dto) {
-            var asMap = mapper.convertValue(obj, Map.class);
-            return this.wrap(asMap);
+        if (obj instanceof Dto dto) {
+            return new DtoTemplateModel(this, dto);
         }
         return super.handleUnknownType(obj);
     }
-
 }