Add Logical Type support for java.util.UUID

avro/README.md

@@ -114,32 +114,34 @@ and that's about it, for now.
 
 ## Avro Logical Types
 
-Following is an extract from [Logical Types](http://avro.apache.org/docs/current/specification/_print/#logical-types) paragraph in 
-Avro schema specification:
+The following is an excerpt from the [Logical Types](https://avro.apache.org/docs/1.11.1/specification/#logical-types) section of
+the Avro schema specification:
+
 > A logical type is an Avro primitive or complex type with extra attributes to represent a derived type. The attribute 
-> `logicalType` is always be present for a logical type, and is a string with the name of one of the logical types 
-> defined by Avro specification.
+> `logicalType` must always be present for a logical type, and is a string with the name of one of the logical types 
+> listed later in this section. Other attributes may be defined for particular logical types.
+
+Logical types are supported for a limited set of `java.time` classes and for 'java.util.UUID'. See the table below for more details.
 
-Generation of logical types for limited set of `java.time` classes is supported at the moment. See a table bellow. 
+### Mapping to Logical Types
 
-### Mapping to Logical Type
+Mapping to Avro type and logical type involves these steps:
 
-Mapping to Avro type and logical type works in few steps: 
-1. Serializer for particular Java type (or class) determines a Jackson type  where the Java type will be serialized into.
-2. `AvroSchemaGenerator` determines corresponding Avro type for that Jackson type.
-2. If logical type generation is enabled, then `logicalType` is determined for the above combination of Java type and 
-   Avro type. 
+1. The serializer for a Java type identifies the Jackson type it will serialize into.
+2. The `AvroSchemaGenerator` maps that Jackson type to the corresponding Avro type.
+3. `logicalType` value is combination of Java type and Jackson type.
 
 #### Java type to Avro Logical Type mapping
 
-| Java type                     | Serialization type | Generated Avro schema with Avro type and logical type
-| ----------------------------- | ------------------ | -----------------------------------------------------
-| `java.time.OffsetDateTime`    | NumberType.LONG    | `{"type": "long", "logicalType": "timestamp-millis"}`
-| `java.time.ZonedDateTime`     | NumberType.LONG    | `{"type": "long", "logicalType": "timestamp-millis"}`
-| `java.time.Instant`           | NumberType.LONG    | `{"type": "long", "logicalType": "timestamp-millis"}`
-| `java.time.LocalDate`         | NumberType.INT     | `{"type": "int",  "logicalType": "date"}`
-| `java.time.LocalTime`         | NumberType.INT     | `{"type": "int",  "logicalType": "time-millis"}`
-| `java.time.LocalDateTime`     | NumberType.LONG    | `{"type": "long", "logicalType": "local-timestamp-millis"}`
+| Java type                  | Jackson type    | Generated Avro schema with logical type                                                           |
+|----------------------------|-----------------|---------------------------------------------------------------------------------------------------|
+| `java.time.OffsetDateTime` | NumberType.LONG | `{"type": "long", "logicalType": "timestamp-millis"}`                                             |
+| `java.time.ZonedDateTime`  | NumberType.LONG | `{"type": "long", "logicalType": "timestamp-millis"}`                                             |
+| `java.time.Instant`        | NumberType.LONG | `{"type": "long", "logicalType": "timestamp-millis"}`                                             |
+| `java.time.LocalDate`      | NumberType.INT  | `{"type": "int",  "logicalType": "date"}`                                                         |
+| `java.time.LocalTime`      | NumberType.INT  | `{"type": "int",  "logicalType": "time-millis"}`                                                  |
+| `java.time.LocalDateTime`  | NumberType.LONG | `{"type": "long", "logicalType": "local-timestamp-millis"}`                                       |
+| `java.util.UUID`           |                 | `{"type": "fixed", "name": "UUID", "namespace": "java.util", "size": 16, "logicalType" : "uuid"}` |
 
 _Provided Avro logical type generation is enabled._
 

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/schema/AvroSchemaHelper.java

@@ -286,7 +286,7 @@ public static Schema createEnumSchema(BeanDescription bean, List<String> values)
      * @since 2.11
      */
     public static Schema createUUIDSchema() {
-        return Schema.createFixed("UUID", "", "java.util", 16);
+        return Schema.createFixed("UUID", null, "java.util", 16);
     }
 
     /**

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/schema/StringVisitor.java

@@ -39,11 +39,7 @@ public Schema builtAvroSchema() {
             // should we construct JavaType for `Character.class` in case of primitive or... ?
             return AvroSchemaHelper.numericAvroSchema(NumberType.INT, _type);
         }
-        // [dataformats-binary#179]: need special help with UUIDs, to coerce into Binary
-        //   (could actually be
-        if (_type.hasRawClass(java.util.UUID.class)) {
-            return AvroSchemaHelper.createUUIDSchema();
-        }
+
         BeanDescription bean = _provider.getConfig().introspectClassAnnotations(_type);
         Schema schema = Schema.create(Schema.Type.STRING);
         // Stringable classes need to include the type

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/schema/UUIDVisitor.java

@@ -0,0 +1,42 @@
+package com.fasterxml.jackson.dataformat.avro.schema;
+
+import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonStringFormatVisitor;
+import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonValueFormat;
+import org.apache.avro.LogicalTypes;
+import org.apache.avro.Schema;
+
+import java.util.Set;
+
+/**
+ * Visitor for {@link java.util.UUID} type. When it is created with logicalTypesEnabled enabled,
+ * Avro schema is created with logical type uuid.
+ *
+ * @since 2.19
+ */
+public class UUIDVisitor extends JsonStringFormatVisitor.Base
+        implements SchemaBuilder {
+    protected boolean _logicalTypesEnabled = false;
+
+
+    public UUIDVisitor(boolean logicalTypesEnabled) {
+        _logicalTypesEnabled = logicalTypesEnabled;
+    }
+
+    @Override
+    public void format(JsonValueFormat format) {
+        // Ideally, we'd recognize UUIDs, Dates etc if need be, here...
+    }
+
+    @Override
+    public void enumTypes(Set<String> enums) {
+        // Do nothing
+    }
+
+    @Override
+    public Schema builtAvroSchema() {
+        // [dataformats-binary#179]: need special help with UUIDs, to coerce into Binary
+        //   (could actually be
+        Schema schema = AvroSchemaHelper.createUUIDSchema();
+        return this._logicalTypesEnabled ? LogicalTypes.uuid().addToSchema(schema) : schema;
+    }
+}

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/schema/VisitorFormatWrapperImpl.java

@@ -214,6 +214,12 @@ public JsonStringFormatVisitor expectStringFormat(JavaType type)
             return v;
         }
 
+        if (type.hasRawClass(java.util.UUID.class)) {
+            UUIDVisitor v = new UUIDVisitor(this._logicalTypesEnabled);
+            _builder = v;
+            return v;
+        }
+
         StringVisitor v = new StringVisitor(_provider, type);
         _builder = v;
         return v;

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/schema/UUIDVisitor_builtAvroSchemaTest.java

@@ -0,0 +1,45 @@
+package com.fasterxml.jackson.dataformat.avro.schema;
+
+import org.apache.avro.LogicalType;
+import org.apache.avro.Schema;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class UUIDVisitor_builtAvroSchemaTest {
+
+    @Test
+    public void testLogicalTypesDisabled() {
+        // GIVEN
+        boolean logicalTypesEnabled = false;
+        UUIDVisitor uuidVisitor = new UUIDVisitor(logicalTypesEnabled);
+
+        // WHEN
+        Schema actualSchema = uuidVisitor.builtAvroSchema();
+
+        // THEN
+        assertThat(actualSchema.getType()).isEqualTo(Schema.Type.FIXED);
+        assertThat(actualSchema.getFixedSize()).isEqualTo(16);
+        assertThat(actualSchema.getName()).isEqualTo("UUID");
+        assertThat(actualSchema.getNamespace()).isEqualTo("java.util");
+        assertThat(actualSchema.getProp(LogicalType.LOGICAL_TYPE_PROP)).isNull();
+    }
+
+    @Test
+    public void testLogicalTypesEnabled() {
+        // GIVEN
+        boolean logicalTypesEnabled = true;
+        UUIDVisitor uuidVisitor = new UUIDVisitor(logicalTypesEnabled);
+
+        // WHEN
+        Schema actualSchema = uuidVisitor.builtAvroSchema();
+
+        // THEN
+        assertThat(actualSchema.getType()).isEqualTo(Schema.Type.FIXED);
+        assertThat(actualSchema.getFixedSize()).isEqualTo(16);
+        assertThat(actualSchema.getName()).isEqualTo("UUID");
+        assertThat(actualSchema.getNamespace()).isEqualTo("java.util");
+        assertThat(actualSchema.getProp(LogicalType.LOGICAL_TYPE_PROP)).isEqualTo("uuid");
+    }
+
+}