src/main/java/com/fasterxml/jackson/databind/ser/BeanPropertyWriter.java

package com.fasterxml.jackson.databind.ser;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.HashMap;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.SerializableString;
import com.fasterxml.jackson.core.io.SerializedString;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.introspect.*;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonObjectFormatVisitor;
import com.fasterxml.jackson.databind.jsonschema.SchemaAware;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.ser.impl.PropertySerializerMap;
import com.fasterxml.jackson.databind.ser.impl.UnwrappingBeanPropertyWriter;
import com.fasterxml.jackson.databind.ser.std.BeanSerializerBase;
import com.fasterxml.jackson.databind.util.Annotations;
import com.fasterxml.jackson.databind.util.NameTransformer;

/**
 * Base bean property handler class, which implements common parts of
 * reflection-based functionality for accessing a property value
 * and serializing it.
 *<p> 
 * Note that current design tries to keep instances immutable (semi-functional
 * style); mostly because these instances are exposed to application
 * code and this is to reduce likelihood of data corruption and
 * synchronization issues.
 */
public class BeanPropertyWriter extends PropertyWriter
    implements BeanProperty
{
    /**
     * Marker object used to indicate "do not serialize if empty"
     */
    public final static Object MARKER_FOR_EMPTY = new Object();
    
    /*
    /**********************************************************
    /* Settings for accessing property value to serialize
    /**********************************************************
     */

    /**
     * Member (field, method) that represents property and allows access
     * to associated annotations.
     */
    protected final AnnotatedMember _member;

    /**
     * Annotations from context (most often, class that declares property,
     * or in case of sub-class serializer, from that sub-class)
     */
    protected final Annotations _contextAnnotations;
    
    /**
     * Type property is declared to have, either in class definition 
     * or associated annotations.
     */
    protected final JavaType _declaredType;
    
    /**
     * Accessor method used to get property value, for
     * method-accessible properties.
     * Null if and only if {@link #_field} is null.
     */
    protected final Method _accessorMethod;
    
    /**
     * Field that contains the property value for field-accessible
     * properties.
     * Null if and only if {@link #_accessorMethod} is null.
     */
    protected final Field _field;
    
    /*
    /**********************************************************
    /* Opaque internal data that bean serializer factory and
    /* bean serializers can add.
    /**********************************************************
     */

    protected HashMap<Object,Object> _internalSettings;
    
    /*
    /**********************************************************
    /* Serialization settings
    /**********************************************************
     */
    
    /**
     * Logical name of the property; will be used as the field name
     * under which value for the property is written.
     */
    protected final SerializableString _name;

    /**
     * Wrapper name to use for this element, if any
     * 
     * @since 2.2
     */
    protected final PropertyName _wrapperName;
    
    /**
     * Type to use for locating serializer; normally same as return
     * type of the accessor method, but may be overridden by annotations.
     */
    protected final JavaType _cfgSerializationType;

    /**
     * Serializer to use for writing out the value: null if it can not
     * be known statically; non-null if it can.
     */
    protected JsonSerializer<Object> _serializer;

    /**
     * Serializer used for writing out null values, if any: if null,
     * null values are to be suppressed.
     */
    protected JsonSerializer<Object> _nullSerializer;
    
    /**
     * In case serializer is not known statically (i.e. <code>_serializer</code>
     * is null), we will use a lookup structure for storing dynamically
     * resolved mapping from type(s) to serializer(s).
     */
    protected transient PropertySerializerMap _dynamicSerializers;

    /**
     * Whether null values are to be suppressed (nothing written out if
     * value is null) or not.
     */
    protected final boolean _suppressNulls;
    
    /**
     * Value that is considered default value of the property; used for
     * default-value-suppression if enabled.
     */
    protected final Object _suppressableValue;

    /**
     * Alternate set of property writers used when view-based filtering
     * is available for the Bean.
     */
    protected final Class<?>[] _includeInViews;

    /**
     * If property being serialized needs type information to be
     * included this is the type serializer to use.
     * Declared type (possibly augmented with annotations) of property
     * is used for determining exact mechanism to use (compared to
     * actual runtime type used for serializing actual state).
     */
    protected TypeSerializer _typeSerializer;
    
    /**
     * Base type of the property, if the declared type is "non-trivial";
     * meaning it is either a structured type (collection, map, array),
     * or parameterized. Used to retain type information about contained
     * type, which is mostly necessary if type meta-data is to be
     * included.
     */
    protected JavaType _nonTrivialBaseType;

    /**
     * Additional information about property
     * 
     * @since 2.3
     */
    protected final PropertyMetadata _metadata;

    /*
    /**********************************************************
    /* Construction, configuration
    /**********************************************************
     */

    @SuppressWarnings("unchecked")
    public BeanPropertyWriter(BeanPropertyDefinition propDef,
            AnnotatedMember member, Annotations contextAnnotations,
            JavaType declaredType,
            JsonSerializer<?> ser, TypeSerializer typeSer, JavaType serType,
            boolean suppressNulls, Object suppressableValue)
    {
        _member = member;
        _contextAnnotations = contextAnnotations;
        _name = new SerializedString(propDef.getName());
        _wrapperName = propDef.getWrapperName();
        _declaredType = declaredType;
        _serializer = (JsonSerializer<Object>) ser;
        _dynamicSerializers = (ser == null) ? PropertySerializerMap.emptyMap() : null;
        _typeSerializer = typeSer;
        _cfgSerializationType = serType;
        _metadata = propDef.getMetadata();

        if (member instanceof AnnotatedField) {
            _accessorMethod = null;
            _field = (Field) member.getMember();
        } else if (member instanceof AnnotatedMethod) {
            _accessorMethod = (Method) member.getMember();
            _field = null;
        } else {
            throw new IllegalArgumentException("Can not pass member of type "+member.getClass().getName());
        }
        _suppressNulls = suppressNulls;
        _suppressableValue = suppressableValue;
        _includeInViews = propDef.findViews();

        // this will be resolved later on, unless nulls are to be suppressed
        _nullSerializer = null;
    }

    /**
     * "Copy constructor" to be used by filtering sub-classes
     */
    protected BeanPropertyWriter(BeanPropertyWriter base) {
        this(base, base._name);
    }

    protected BeanPropertyWriter(BeanPropertyWriter base, SerializableString name) {
        _name = name;
        _wrapperName = base._wrapperName;

        _member = base._member;
        _contextAnnotations = base._contextAnnotations;
        _declaredType = base._declaredType;
        _accessorMethod = base._accessorMethod;
        _field = base._field;
        _serializer = base._serializer;
        _nullSerializer = base._nullSerializer;
        // one more thing: copy internal settings, if any (since 1.7)
        if (base._internalSettings != null) {
            _internalSettings = new HashMap<Object,Object>(base._internalSettings);
        }
        _cfgSerializationType = base._cfgSerializationType;
        _dynamicSerializers = base._dynamicSerializers;
        _suppressNulls = base._suppressNulls;
        _suppressableValue = base._suppressableValue;
        _includeInViews = base._includeInViews;
        _typeSerializer = base._typeSerializer;
        _nonTrivialBaseType = base._nonTrivialBaseType;
        _metadata = base._metadata;
    }

    public BeanPropertyWriter rename(NameTransformer transformer) {
        String newName = transformer.transform(_name.getValue());
        if (newName.equals(_name.toString())) {
            return this;
        }
        return new BeanPropertyWriter(this, new SerializedString(newName));
    }
    
    /**
     * Method called to assign value serializer for property
     * 
     * @since 2.0
     */
    public void assignSerializer(JsonSerializer<Object> ser) {
        // may need to disable check in future?
        if (_serializer != null && _serializer != ser) {
            throw new IllegalStateException("Can not override serializer");
        }
        _serializer = ser;
    }

    /**
     * Method called to assign null value serializer for property
     * 
     * @since 2.0
     */
    public void assignNullSerializer(JsonSerializer<Object> nullSer) {
        // may need to disable check in future?
        if (_nullSerializer != null && _nullSerializer != nullSer) {
            throw new IllegalStateException("Can not override null serializer");
        }
        _nullSerializer = nullSer;
    }
    
    /**
     * Method called create an instance that handles details of unwrapping
     * contained value.
     */
    public BeanPropertyWriter unwrappingWriter(NameTransformer unwrapper) {
        return new UnwrappingBeanPropertyWriter(this, unwrapper);
    }

    /**
     * Method called to define type to consider as "non-trivial" basetype,
     * needed for dynamic serialization resolution for complex (usually container)
     * types
     */
    public void setNonTrivialBaseType(JavaType t) {
        _nonTrivialBaseType = t;
    }

    /*
    /**********************************************************
    /* BeanProperty impl
    /**********************************************************
     */

    // Note: also part of 'PropertyWriter'
    @Override public String getName() { return _name.getValue(); }

    // Note: also part of 'PropertyWriter'
    @Override public PropertyName getFullName() { // !!! TODO: impl properly
        return new PropertyName(_name.getValue());
    }
    
    @Override public JavaType getType() { return _declaredType; }
    @Override public PropertyName getWrapperName() { return _wrapperName; }
    @Override public boolean isRequired() { return _metadata.isRequired(); }
    @Override public PropertyMetadata getMetadata() { return _metadata; }
    
    @Override
    public <A extends Annotation> A getAnnotation(Class<A> acls) {
        return _member.getAnnotation(acls);
    }

    @Override
    public <A extends Annotation> A getContextAnnotation(Class<A> acls) {
        return _contextAnnotations.get(acls);
    }

    @Override public AnnotatedMember getMember() { return _member; }

    // @since 2.3 -- needed so it can be overridden by unwrapping writer
    protected void _depositSchemaProperty(ObjectNode propertiesNode, JsonNode schemaNode) {
        propertiesNode.set(getName(), schemaNode);
    }
    
    /*
    /**********************************************************
    /* Managing and accessing of opaque internal settings
    /* (used by extensions)
    /**********************************************************
     */
    
    /**
     * Method for accessing value of specified internal setting.
     * 
     * @return Value of the setting, if any; null if none.
     */
    public Object getInternalSetting(Object key)  {
        return (_internalSettings == null) ? null : _internalSettings.get(key);
    }
    
    /**
     * Method for setting specific internal setting to given value
     * 
     * @return Old value of the setting, if any (null if none)
     */
    public Object setInternalSetting(Object key, Object value) {
        if (_internalSettings == null) {
            _internalSettings = new HashMap<Object,Object>();
        }
        return _internalSettings.put(key, value);
    }

    /**
     * Method for removing entry for specified internal setting.
     * 
     * @return Existing value of the setting, if any (null if none)
     */
    public Object removeInternalSetting(Object key) {
        Object removed = null;
        if (_internalSettings != null) {
            removed = _internalSettings.remove(key);
            // to reduce memory usage, let's also drop the Map itself, if empty
            if (_internalSettings.size() == 0) {
                _internalSettings = null;
            }
        }
        return removed;
    }
    
    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */

    public SerializableString getSerializedName() { return _name; }
    
    public boolean hasSerializer() { return _serializer != null; }
    public boolean hasNullSerializer() { return _nullSerializer != null; }

    /**
     * Accessor that will return true if this bean property has to support
     * "unwrapping"; ability to replace POJO structural wrapping with optional
     * name prefix and/or suffix (or in some cases, just removal of wrapper name).
     *<p>
     * Default implementation simply returns false.
     * 
     * @since 2.3
     */
    public boolean isUnwrapping() { return false; }
    
    public boolean willSuppressNulls() { return _suppressNulls; }
    
    // Needed by BeanSerializer#getSchema
    public JsonSerializer<Object> getSerializer() { return _serializer; }

    public JavaType getSerializationType() { return _cfgSerializationType; }

    public Class<?> getRawSerializationType() {
        return (_cfgSerializationType == null) ? null : _cfgSerializationType.getRawClass();
    }
    
    public Class<?> getPropertyType() {
        return (_accessorMethod != null) ? _accessorMethod.getReturnType() : _field.getType();
    }

    /**
     * Get the generic property type of this property writer.
     *
     * @return The property type, or null if not found.
     */
    public Type getGenericPropertyType() {
        if (_accessorMethod != null) {
            return _accessorMethod.getGenericReturnType();
        }
        return _field.getGenericType();
    }

    public Class<?>[] getViews() { return _includeInViews; }

    /**
     *<p>
     * NOTE: due to introspection, this is a <b>slow</b> method to call
     * and should never be called during actual serialization or filtering
     * of the property. Rather it is needed for traversal needed for things
     * like constructing JSON Schema instances.
     * 
     * @since 2.1
     * 
     * @deprecated since 2.2, use {@link #isRequired()} instead.
     */
    @Deprecated
    protected boolean isRequired(AnnotationIntrospector intr) { return _metadata.isRequired(); }
    
    /*
    /**********************************************************
    /* PropertyWriter methods (serialization)
    /**********************************************************
     */

    /**
     * Method called to access property that this bean stands for, from
     * within given bean, and to serialize it as a JSON Object field
     * using appropriate serializer.
     */
    @Override
    public void serializeAsField(Object bean, JsonGenerator jgen, SerializerProvider prov) throws Exception
    {
        Object value = get(bean);
        // Null handling is bit different, check that first
        if (value == null) {
            if (_nullSerializer != null) {
                jgen.writeFieldName(_name);
                _nullSerializer.serialize(null, jgen, prov);
            }
            return;
        }
        // then find serializer to use
        JsonSerializer<Object> ser = _serializer;
        if (ser == null) {
            Class<?> cls = value.getClass();
            PropertySerializerMap m = _dynamicSerializers;
            ser = m.serializerFor(cls);
            if (ser == null) {
                ser = _findAndAddDynamic(m, cls, prov);
            }
        }
        // and then see if we must suppress certain values (default, empty)
        if (_suppressableValue != null) {
            if (MARKER_FOR_EMPTY == _suppressableValue) {
                if (ser.isEmpty(value)) {
                    return;
                }
            } else if (_suppressableValue.equals(value)) {
                return;
            }
        }
        // For non-nulls: simple check for direct cycles
        if (value == bean) {
            // three choices: exception; handled by call; or pass-through
            if (_handleSelfReference(bean, jgen, prov, ser)) {
                return;
            }
        }
        jgen.writeFieldName(_name);
        if (_typeSerializer == null) {
            ser.serialize(value, jgen, prov);
        } else {
            ser.serializeWithType(value, jgen, prov, _typeSerializer);
        }
    }

    /**
     * Method called to indicate that serialization of a field was omitted
     * due to filtering, in cases where backend data format does not allow
     * basic omission.
     * 
     * @since 2.3
     */
    @Override
    public void serializeAsOmittedField(Object bean, JsonGenerator jgen, SerializerProvider prov) throws Exception
    {
        if (!jgen.canOmitFields()) {
            jgen.writeOmittedField(_name.getValue());
        }
    }
    
    /**
     * Alternative to {@link #serializeAsField} that is used when a POJO
     * is serialized as JSON Array; the difference is that no field names
     * are written.
     * 
     * @since 2.3
     */
    @Override
    public void serializeAsElement(Object bean, JsonGenerator jgen, SerializerProvider prov)
        throws Exception
    {
        Object value = get(bean);
        if (value == null) { // nulls need specialized handling
            if (_nullSerializer != null) {
                _nullSerializer.serialize(null, jgen, prov);
            } else { // can NOT suppress entries in tabular output
                jgen.writeNull();
            }
            return;
        }
        // otherwise find serializer to use
        JsonSerializer<Object> ser = _serializer;
        if (ser == null) {
            Class<?> cls = value.getClass();
            PropertySerializerMap map = _dynamicSerializers;
            ser = map.serializerFor(cls);
            if (ser == null) {
                ser = _findAndAddDynamic(map, cls, prov);
            }
        }
        // and then see if we must suppress certain values (default, empty)
        if (_suppressableValue != null) {
            if (MARKER_FOR_EMPTY == _suppressableValue) {
                if (ser.isEmpty(value)) { // can NOT suppress entries in tabular output
                    serializeAsPlaceholder(bean, jgen, prov);
                    return;
                }
            } else if (_suppressableValue.equals(value)) { // can NOT suppress entries in tabular output
                serializeAsPlaceholder(bean, jgen, prov);
                return;
            }
        }
        // For non-nulls: simple check for direct cycles
        if (value == bean) {
            if (_handleSelfReference(bean, jgen, prov, ser)) {
                return;
            }
        }
        if (_typeSerializer == null) {
            ser.serialize(value, jgen, prov);
        } else {
            ser.serializeWithType(value, jgen, prov, _typeSerializer);
        }
    }

    /**
     * Method called to serialize a placeholder used in tabular output when
     * real value is not to be included (is filtered out), but when we need
     * an entry so that field indexes will not be off. Typically this should
     * output null or empty String, depending on datatype.
     * 
     * @since 2.1
     */
    @Override
    public void serializeAsPlaceholder(Object bean, JsonGenerator jgen, SerializerProvider prov)
        throws Exception
    {
        if (_nullSerializer != null) {
            _nullSerializer.serialize(null, jgen, prov);
        } else {
            jgen.writeNull();
        }
    }
    
    /*
    /**********************************************************
    /* PropertyWriter methods (schema generation)
    /**********************************************************
     */

    // Also part of BeanProperty implementation
    @Override
    public void depositSchemaProperty(JsonObjectFormatVisitor objectVisitor)
        throws JsonMappingException
    {
        if (objectVisitor != null) {
            if (isRequired()) {
                objectVisitor.property(this); 
            } else {
                objectVisitor.optionalProperty(this);
            }
        }
    }

    // // // Legacy support for JsonFormatVisitable

    /**
     * Attempt to add the output of the given {@link BeanPropertyWriter} in the given {@link ObjectNode}.
     * Otherwise, add the default schema {@link JsonNode} in place of the writer's output
     * 
     * @param propertiesNode Node which the given property would exist within
     * @param provider Provider that can be used for accessing dynamic aspects of serialization
     *  processing
     */
    @Override
    @Deprecated
    public void depositSchemaProperty(ObjectNode propertiesNode, SerializerProvider provider)
        throws JsonMappingException
    {
        JavaType propType = getSerializationType();
        // 03-Dec-2010, tatu: SchemaAware REALLY should use JavaType, but alas it doesn't...
        Type hint = (propType == null) ? getGenericPropertyType() : propType.getRawClass();
        JsonNode schemaNode;
        // Maybe it already has annotated/statically configured serializer?
        JsonSerializer<Object> ser = getSerializer();
        if (ser == null) { // nope
            Class<?> serType = getRawSerializationType();
            if (serType == null) {
                serType = getPropertyType();
            }
            ser = provider.findValueSerializer(serType, this);
        }
        boolean isOptional = !isRequired();
        if (ser instanceof SchemaAware) {
            schemaNode =  ((SchemaAware) ser).getSchema(provider, hint, isOptional) ;
        } else {  
            schemaNode = com.fasterxml.jackson.databind.jsonschema.JsonSchema.getDefaultSchemaNode(); 
        }
        _depositSchemaProperty(propertiesNode, schemaNode);
    }
    
    /*
    /**********************************************************
    /* Helper methods
    /**********************************************************
     */
    
    protected JsonSerializer<Object> _findAndAddDynamic(PropertySerializerMap map,
            Class<?> type, SerializerProvider provider) throws JsonMappingException
    {
        PropertySerializerMap.SerializerAndMapResult result;
        if (_nonTrivialBaseType != null) {
            JavaType t = provider.constructSpecializedType(_nonTrivialBaseType, type);
            result = map.findAndAddPrimarySerializer(t, provider, this);
        } else {
            result = map.findAndAddPrimarySerializer(type, provider, this);
        }
        // did we get a new map of serializers? If so, start using it
        if (map != result.map) {
            _dynamicSerializers = result.map;
        }
        return result.serializer;
    }
    
    /**
     * Method that can be used to access value of the property this
     * Object describes, from given bean instance.
     *<p>
     * Note: method is final as it should not need to be overridden -- rather,
     * calling method(s) ({@link #serializeAsField}) should be overridden
     * to change the behavior
     */
    public final Object get(Object bean) throws Exception
    {
        if (_accessorMethod != null) {
            return _accessorMethod.invoke(bean);
        }
        return _field.get(bean);
    }

    /**
     * Method called to handle a direct self-reference through this property.
     * Method can choose to indicate an error by throwing {@link JsonMappingException};
     * fully handle serialization (and return true); or indicate that it should be
     * serialized normally (return false).
     *<p>
     * Default implementation will throw {@link JsonMappingException} if
     * {@link SerializationFeature#FAIL_ON_SELF_REFERENCES} is enabled;
     * or return <code>false</code> if it is disabled.
     *
     * @return True if method fully handled self-referential value; false if not (caller
     *    is to handle it) or {@link JsonMappingException} if there is no way handle it
     */
    protected boolean _handleSelfReference(Object bean, JsonGenerator jgen, SerializerProvider prov, JsonSerializer<?> ser)
            throws JsonMappingException {
        if (prov.isEnabled(SerializationFeature.FAIL_ON_SELF_REFERENCES)
                && !ser.usesObjectId()) {
            // 05-Feb-2013, tatu: Usually a problem, but NOT if we are handling
            //    object id; this may be the case for BeanSerializers at least.
            // 13-Feb-2014, tatu: another possible ok case: custom serializer (something
            //   OTHER than {@link BeanSerializerBase}
            if (ser instanceof BeanSerializerBase) {
                throw new JsonMappingException("Direct self-reference leading to cycle");
            }
        }
        return false;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(40);
        sb.append("property '").append(getName()).append("' (");
        if (_accessorMethod != null) {
            sb.append("via method ").append(_accessorMethod.getDeclaringClass().getName()).append("#").append(_accessorMethod.getName());
        } else {
            sb.append("field \"").append(_field.getDeclaringClass().getName()).append("#").append(_field.getName());
        }
        if (_serializer == null) {
            sb.append(", no static serializer");
        } else {
            sb.append(", static serializer of type "+_serializer.getClass().getName());
        }
        sb.append(')');
        return sb.toString();
    }
}