chore(example): add enum map example (#377)

demonstrate dynamic object schema creation from map with enum keys

jsonschema-examples/src/main/java/com/github/victools/jsonschema/examples/EnumMapExample.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2023 VicTools.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.github.victools.jsonschema.examples;
+
+import com.fasterxml.classmate.ResolvedType;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.github.victools.jsonschema.generator.CustomDefinition;
+import com.github.victools.jsonschema.generator.CustomDefinitionProviderV2;
+import com.github.victools.jsonschema.generator.Option;
+import com.github.victools.jsonschema.generator.OptionPreset;
+import com.github.victools.jsonschema.generator.SchemaGenerationContext;
+import com.github.victools.jsonschema.generator.SchemaGenerator;
+import com.github.victools.jsonschema.generator.SchemaGeneratorConfig;
+import com.github.victools.jsonschema.generator.SchemaGeneratorConfigBuilder;
+import com.github.victools.jsonschema.generator.SchemaKeyword;
+import com.github.victools.jsonschema.generator.SchemaVersion;
+import com.github.victools.jsonschema.generator.TypeAttributeOverrideV2;
+import com.github.victools.jsonschema.generator.TypeContext;
+import com.github.victools.jsonschema.generator.TypeScope;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.lang.reflect.Type;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Example created in response to <a href="https://github.com/victools/jsonschema-generator/discussions/376">#376</a>.
+ * <br/>
+ * Representing a Map containing Enum values as keys.
+ */
+public class EnumMapExample implements SchemaGenerationExampleInterface {
+
+    @Override
+    public ObjectNode generateSchema() {
+        SchemaGeneratorConfigBuilder configBuilder = new SchemaGeneratorConfigBuilder(SchemaVersion.DRAFT_2020_12, OptionPreset.PLAIN_JSON);
+        configBuilder.forTypesInGeneral()
+                .withCustomDefinitionProvider(new EnumMapDefinitionProvider(enumValue -> enumValue.name().toLowerCase()));
+        SchemaGeneratorConfig config = configBuilder.build();
+        SchemaGenerator generator = new SchemaGenerator(config);
+        return generator.generateSchema(Map.class, Job.class, JobDetails.class);
+    }
+
+    class EnumMapDefinitionProvider implements CustomDefinitionProviderV2 {
+
+        private Function<Enum<?>, String> propertyNameSupplier;
+
+        EnumMapDefinitionProvider(Function<Enum<?>, String> propertyNameSupplier) {
+            this.propertyNameSupplier = propertyNameSupplier;
+        }
+
+        @Override
+        public CustomDefinition provideCustomSchemaDefinition(ResolvedType targetType, SchemaGenerationContext context) {
+            ResolvedType keyType = context.getTypeContext().getTypeParameterFor(targetType, Map.class, 0);
+            if (keyType == null || !keyType.isInstanceOf(Enum.class)) {
+                // only consider Maps with an Enum as key
+                return null;
+            }
+            ResolvedType valueType = Optional.ofNullable(context.getTypeContext().getTypeParameterFor(targetType, Map.class, 1))
+                    .orElseGet(()  -> context.getTypeContext().resolve(Object.class));
+            ObjectNode customSchema = context.getGeneratorConfig().createObjectNode();
+            ObjectNode propertiesNode = context.getGeneratorConfig().createObjectNode();
+            customSchema.set(context.getKeyword(SchemaKeyword.TAG_PROPERTIES), propertiesNode);
+            Stream.of(((Class<? extends Enum<?>>) keyType.getErasedType()).getEnumConstants())
+                    .map(this.propertyNameSupplier)
+                    .forEach(propertyName -> propertiesNode.set(propertyName,
+                            context.createStandardDefinitionReference(valueType, this)));
+            return new CustomDefinition(customSchema);
+        }
+    }
+
+    enum Job {
+        BLACKSMITH, FARMER;
+    }
+
+    static class JobDetails {
+        public Map<TrainingResource, Integer> trainingCosts;
+    }
+
+    enum TrainingResource {
+        WOOD, FOOD, STONE;
+    }
+}

jsonschema-examples/src/test/java/com/github/victools/jsonschema/examples/ExampleTest.java

@@ -32,6 +32,7 @@ public class ExampleTest {
     @ParameterizedTest
     @ValueSource(classes = {
             AnnotationInheritanceExample.class,
+            EnumMapExample.class,
             ExternalRefAnnotationExample.class,
             ExternalRefPackageExample.class,
             IfThenElseExample.class,

jsonschema-examples/src/test/resources/com/github/victools/jsonschema/examples/EnumMapExample-result.json

@@ -0,0 +1,31 @@
+{
+    "$schema" : "https://json-schema.org/draft/2020-12/schema",
+    "$defs" : {
+        "JobDetails" : {
+            "type" : "object",
+            "properties" : {
+                "trainingCosts" : {
+                    "properties" : {
+                        "wood" : {
+                            "type" : "integer"
+                        },
+                        "food" : {
+                            "type" : "integer"
+                        },
+                        "stone" : {
+                            "type" : "integer"
+                        }
+                    }
+                }
+            }
+        }
+    },
+    "properties" : {
+        "blacksmith" : {
+            "$ref" : "#/$defs/JobDetails"
+        },
+        "farmer" : {
+            "$ref" : "#/$defs/JobDetails"
+        }
+    }
+}