[Avro] Add support for @Stringable annotation

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/AvroAnnotationIntrospector.java

@@ -1,14 +1,20 @@
 package com.fasterxml.jackson.dataformat.avro;
 
+import java.io.File;
+
+import org.apache.avro.reflect.AvroDefault;
+import org.apache.avro.reflect.AvroIgnore;
+import org.apache.avro.reflect.AvroName;
+import org.apache.avro.reflect.Stringable;
+
 import com.fasterxml.jackson.core.Version;
 import com.fasterxml.jackson.databind.AnnotationIntrospector;
 import com.fasterxml.jackson.databind.PropertyName;
 import com.fasterxml.jackson.databind.introspect.Annotated;
+import com.fasterxml.jackson.databind.introspect.AnnotatedClass;
+import com.fasterxml.jackson.databind.introspect.AnnotatedConstructor;
 import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
-
-import org.apache.avro.reflect.AvroDefault;
-import org.apache.avro.reflect.AvroIgnore;
-import org.apache.avro.reflect.AvroName;
+import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
 
 /**
  * Adds support for the following annotations from the Apache Avro implementation:
@@ -18,6 +24,8 @@
  * <li>{@link AvroDefault @AvroDefault("default value")} - Alias for <code>JsonProperty.defaultValue</code>, to
  *     define default value for generated Schemas
  *   </li>
+ * <li>{@link Stringable @Stringable} - Alias for <code>JsonCreator</code> on the constructor and <code>JsonValue</code> on
+ * the {@link #toString()} method. </li>
  * </ul>
  *
  * @since 2.9
@@ -57,4 +65,23 @@ protected PropertyName _findName(Annotated a)
         AvroName ann = _findAnnotation(a, AvroName.class);
         return (ann == null) ? null : PropertyName.construct(ann.value());
     }
+
+    @Override
+    public boolean hasCreatorAnnotation(Annotated a) {
+        AnnotatedConstructor constructor = a instanceof AnnotatedConstructor ? (AnnotatedConstructor) a : null;
+        AnnotatedClass parentClass =
+            a instanceof AnnotatedConstructor && ((AnnotatedConstructor) a).getTypeContext() instanceof AnnotatedClass
+            ? (AnnotatedClass) ((AnnotatedConstructor) a).getTypeContext()
+            : null;
+        return constructor != null && parentClass != null && parentClass.hasAnnotation(Stringable.class)
+            && constructor.getParameterCount() == 1 && String.class.equals(constructor.getRawParameterType(0));
+    }
+
+    @Override
+    public Object findSerializer(Annotated a) {
+        if (a instanceof AnnotatedClass && a.hasAnnotation(Stringable.class) || a.getRawType() == File.class) {
+            return ToStringSerializer.class;
+        }
+        return null;
+    }
 }

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/AvroParser.java

@@ -1,6 +1,9 @@
 package com.fasterxml.jackson.dataformat.avro;
 
-import java.io.*;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.Writer;
+import java.math.BigDecimal;
 
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.core.base.ParserBase;
@@ -281,6 +284,17 @@ public JsonLocation getCurrentLocation()
     @Override
     public abstract JsonToken nextToken() throws IOException;
 
+    @Override
+    protected void convertNumberToBigDecimal() throws IOException {
+        // ParserBase uses _textValue instead of _numberDouble for some reason when NR_DOUBLE is set, but _textValue is not set by setNumber()
+        // Catch and use _numberDouble instead
+        if ((_numTypesValid & NR_DOUBLE) != 0 && _textValue == null) {
+            _numberBigDecimal = BigDecimal.valueOf(_numberDouble);
+            return;
+        }
+        super.convertNumberToBigDecimal();
+    }
+
     /*
     /**********************************************************
     /* String value handling

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

@@ -145,14 +145,15 @@ public static Schema numericAvroSchema(JsonParser.NumberType type) {
         switch (type) {
         case INT:
             return Schema.create(Schema.Type.INT);
-        case BIG_INTEGER:
         case LONG:
             return Schema.create(Schema.Type.LONG);
         case FLOAT:
             return Schema.create(Schema.Type.FLOAT);
-        case BIG_DECIMAL:
         case DOUBLE:
             return Schema.create(Schema.Type.DOUBLE);
+        case BIG_INTEGER:
+        case BIG_DECIMAL:
+            return Schema.create(Schema.Type.STRING);
         default:
         }
         throw new IllegalStateException("Unrecognized number type: "+type);
@@ -211,6 +212,17 @@ public static Schema parseJsonSchema(String json) {
         return parser.parse(json);
     }
 
+    /**
+     * Constructs a new enum schema
+     *
+     * @param bean Enum type to use for name / description / namespace
+     * @param values List of enum names
+     * @return An {@link org.apache.avro.Schema.Type#ENUM ENUM} schema.
+     */
+    public static Schema createEnumSchema(BeanDescription bean, List<String> values) {
+        return Schema.createEnum(getName(bean.getType()), bean.findClassDescription(), getNamespace(bean.getType()), values);
+    }
+
     /**
      * Returns the Avro type ID for a given type
      */

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

@@ -3,15 +3,19 @@
 import org.apache.avro.Schema;
 
 import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonNumberFormatVisitor;
 
 public class DoubleVisitor
     extends JsonNumberFormatVisitor.Base
     implements SchemaBuilder
 {
+    protected final JavaType _hint;
     protected JsonParser.NumberType _type;
 
-    public DoubleVisitor() { }
+    public DoubleVisitor(JavaType typeHint) {
+        _hint = typeHint;
+    }
 
     @Override
     public void numberType(JsonParser.NumberType type) {
@@ -25,6 +29,6 @@ public Schema builtAvroSchema() {
             //    would require union most likely
             return AvroSchemaHelper.anyNumberSchema();
         }
-        return AvroSchemaHelper.numericAvroSchema(_type);
+        return AvroSchemaHelper.numericAvroSchema(_type, _hint);
     }
 }

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

@@ -12,11 +12,13 @@ public class MapVisitor extends JsonMapFormatVisitor.Base
     implements SchemaBuilder
 {
     protected final JavaType _type;
-    
+
     protected final DefinedSchemas _schemas;
 
     protected Schema _valueSchema;
-
+
+    protected JavaType _keyType;
+
     public MapVisitor(SerializerProvider p, JavaType type, DefinedSchemas schemas)
     {
         super(p);
@@ -30,7 +32,23 @@ public Schema builtAvroSchema() {
         if (_valueSchema == null) {
             throw new IllegalStateException("Missing value type for "+_type);
         }
-        return Schema.createMap(_valueSchema);
+
+        Schema schema = Schema.createMap(_valueSchema);
+
+        // add the key type if there is one
+        if (_keyType != null && AvroSchemaHelper.isStringable(getProvider()
+                                                                  .getConfig()
+                                                                  .introspectClassAnnotations(_keyType)
+                                                                  .getClassInfo())) {
+            schema.addProp(AvroSchemaHelper.AVRO_SCHEMA_PROP_KEY_CLASS, AvroSchemaHelper.getTypeId(_keyType));
+        } else if (_keyType != null && !_keyType.isEnumType()) {
+            // Avro handles non-stringable keys by converting the map to an array of key/value records
+            // TODO add support for these in the schema, and custom serializers / deserializers to handle map restructuring
+            throw new UnsupportedOperationException(
+                "Key " + _keyType + " is not stringable and non-stringable map keys are not supported yet.");
+        }
+
+        return schema;
     }
 
     /*
@@ -43,12 +61,7 @@ public Schema builtAvroSchema() {
     public void keyFormat(JsonFormatVisitable handler, JavaType keyType)
         throws JsonMappingException
     {
-        /* We actually don't care here, since Avro only has String-keyed
-         * Maps like JSON: meaning that anything Jackson can regularly
-         * serialize must convert to Strings anyway.
-         * If we do find problem cases, we can start verifying them here,
-         * but for now assume it all "just works".
-         */
+        _keyType = keyType;
     }
 
     @Override

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

@@ -6,22 +6,26 @@
 import org.apache.avro.Schema;
 
 import com.fasterxml.jackson.core.JsonParser.NumberType;
+import com.fasterxml.jackson.databind.BeanDescription;
 import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonStringFormatVisitor;
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonValueFormat;
 import com.fasterxml.jackson.databind.type.TypeFactory;
 
 public class StringVisitor extends JsonStringFormatVisitor.Base
     implements SchemaBuilder
 {
+    protected final SerializerProvider _provider;
     protected final JavaType _type;
     protected final DefinedSchemas _schemas;
 
     protected Set<String> _enums;
 
-    public StringVisitor(DefinedSchemas schemas, JavaType t) {
+    public StringVisitor(SerializerProvider provider, DefinedSchemas schemas, JavaType t) {
         _schemas = schemas;
         _type = t;
+        _provider = provider;
     }
 
     @Override
@@ -40,13 +44,17 @@ public Schema builtAvroSchema() {
         if (_type.hasRawClass(char.class) || _type.hasRawClass(Character.class)) {
             return AvroSchemaHelper.numericAvroSchema(NumberType.INT, TypeFactory.defaultInstance().constructType(Character.class));
         }
-        if (_enums == null) {
-            return Schema.create(Schema.Type.STRING);
+        BeanDescription bean = _provider.getConfig().introspectClassAnnotations(_type);
+        if (_enums != null) {
+            Schema s = AvroSchemaHelper.createEnumSchema(bean, new ArrayList<>(_enums));
+            _schemas.addSchema(_type, s);
+            return s;
         }
-        Schema s = Schema.createEnum(AvroSchemaHelper.getName(_type), "",
-                AvroSchemaHelper.getNamespace(_type),
-                new ArrayList<String>(_enums));
-        _schemas.addSchema(_type, s);
-        return s;
+        Schema schema = Schema.create(Schema.Type.STRING);
+        // Stringable classes need to include the type
+        if (AvroSchemaHelper.isStringable(bean.getClassInfo())) {
+            schema.addProp(AvroSchemaHelper.AVRO_SCHEMA_PROP_CLASS, AvroSchemaHelper.getTypeId(_type));
+        }
+        return schema;
     }
 }

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

@@ -118,14 +118,14 @@ public JsonStringFormatVisitor expectStringFormat(JavaType type)
             _valueSchema = s;
             return null;
         }
-        StringVisitor v = new StringVisitor(_schemas, type);
+        StringVisitor v = new StringVisitor(_provider, _schemas, type);
         _builder = v;
         return v;
     }
 
     @Override
     public JsonNumberFormatVisitor expectNumberFormat(JavaType convertedType) {
-        DoubleVisitor v = new DoubleVisitor();
+        DoubleVisitor v = new DoubleVisitor(convertedType);
         _builder = v;
         return v;
     }

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/ser/NonBSGenericDatumWriter.java

@@ -9,6 +9,7 @@
 import org.apache.avro.Schema.Type;
 import org.apache.avro.generic.GenericDatumWriter;
 import org.apache.avro.io.Encoder;
+import org.apache.avro.reflect.Stringable;
 
 import com.fasterxml.jackson.dataformat.avro.schema.AvroSchemaHelper;
 
@@ -58,11 +59,17 @@ public int resolveUnion(Schema union, Object datum) {
                 }
             }
         } else if (datum instanceof BigDecimal) {
+            int subOptimal = -1;
             for (int i = 0, len = schemas.size(); i < len; i++) {
-                if (schemas.get(i).getType() == Type.DOUBLE) {
+                if (schemas.get(i).getType() == Type.STRING) {
                     return i;
+                } else if (schemas.get(i).getType() == Type.DOUBLE) {
+                    subOptimal = i;
                 }
             }
+            if (subOptimal > -1) {
+                return subOptimal;
+            }
         }
 
         // otherwise just default to base impl, stupid as it is...
@@ -71,8 +78,29 @@ public int resolveUnion(Schema union, Object datum) {
 
     @Override
     protected void write(Schema schema, Object datum, Encoder out) throws IOException {
-        if ((schema.getType() == Type.DOUBLE) && datum instanceof BigDecimal) {
-            out.writeDouble(((BigDecimal)datum).doubleValue());
+        // Cocerce numerical types, like BigDecimal -> double and BigInteger -> long
+        if (datum instanceof Number) {
+            switch (schema.getType()) {
+            case LONG:
+                super.write(schema, (((Number) datum).longValue()), out);
+                return;
+            case INT:
+                super.write(schema, (((Number) datum).intValue()), out);
+                return;
+            case FLOAT:
+                super.write(schema, (((Number) datum).floatValue()), out);
+                return;
+            case DOUBLE:
+                super.write(schema, (((Number) datum).doubleValue()), out);
+                return;
+            case STRING:
+                super.write(schema, datum.toString(), out);
+                return;
+            }
+        }
+        // Handle stringable classes
+        if (schema.getType() == Type.STRING && datum != null && datum.getClass().getAnnotation(Stringable.class) != null) {
+            super.write(schema, datum.toString(), out);
             return;
         }
         if (datum instanceof String) {