package com.facebook.presto.jdbc.internal.jackson.databind.ser.impl;
import java.io.IOException;
import com.facebook.presto.jdbc.internal.jackson.core.JsonGenerationException;
import com.facebook.presto.jdbc.internal.jackson.core.JsonGenerator;
import com.facebook.presto.jdbc.internal.jackson.databind.JsonMappingException;
import com.facebook.presto.jdbc.internal.jackson.databind.JsonSerializer;
import com.facebook.presto.jdbc.internal.jackson.databind.SerializationFeature;
import com.facebook.presto.jdbc.internal.jackson.databind.SerializerProvider;
import com.facebook.presto.jdbc.internal.jackson.databind.jsontype.TypeSerializer;
import com.facebook.presto.jdbc.internal.jackson.databind.ser.BeanPropertyWriter;
import com.facebook.presto.jdbc.internal.jackson.databind.ser.std.BeanSerializerBase;
import com.facebook.presto.jdbc.internal.jackson.databind.util.NameTransformer;
/**
* Specialized POJO serializer that differs from
* {@link com.facebook.presto.jdbc.internal.jackson.databind.ser.BeanSerializer}
* in that instead of producing a JSON Object it will output
* a JSON Array, omitting field names, and serializing values in
* specified serialization order.
* This behavior is usually triggered by using annotation
* {@link com.facebook.presto.jdbc.internal.jackson.annotation.JsonFormat} or its
* equivalents.
*<p>
* This serializer can be used for "simple" instances; and will NOT
* be used if one of following is true:
*<ul>
* <li>Unwrapping is used (no way to expand out array in JSON Object)
* </li>
* <li>Type information ("type id") is to be used: while this could work
* for some embedding methods, it would likely cause conflicts.
* </li>
* <li>Object Identity ("object id") is used: while references would work,
* the problem is inclusion of id itself.
* </li>
*</ul>
* Note that it is theoretically possible that last 2 issues could be addressed
* (by reserving room in array, for example); and if so, support improved.
*<p>
* In cases where array-based output is not feasible, this serializer
* can instead delegate to the original Object-based serializer; this
* is why a reference is retained to the original serializer.
*
* @since 2.1
*/
public class BeanAsArraySerializer
extends BeanSerializerBase
{
/**
* Serializer that would produce JSON Object version; used in
* cases where array output can not be used.
*/
protected final BeanSerializerBase _defaultSerializer;
/*
/**********************************************************
/* Life-cycle: constructors
/**********************************************************
*/
public BeanAsArraySerializer(BeanSerializerBase src) {
super(src, (ObjectIdWriter) null);
_defaultSerializer = src;
}
protected BeanAsArraySerializer(BeanSerializerBase src, String[] toIgnore) {
super(src, toIgnore);
_defaultSerializer = src;
}
/*
/**********************************************************
/* Life-cycle: factory methods, fluent factories
/**********************************************************
*/
@Override
public JsonSerializer<Object> unwrappingSerializer(NameTransformer transformer) {
/* If this gets called, we will just need delegate to the default
* serializer, to "undo" as-array serialization
*/
return _defaultSerializer.unwrappingSerializer(transformer);
}
@Override
public boolean isUnwrappingSerializer() {
return false;
}
@Override
public BeanSerializerBase withObjectIdWriter(ObjectIdWriter objectIdWriter) {
// can't handle Object Ids, for now, so:
return _defaultSerializer.withObjectIdWriter(objectIdWriter);
}
@Override
protected BeanAsArraySerializer withIgnorals(String[] toIgnore) {
return new BeanAsArraySerializer(this, toIgnore);
}
@Override
protected BeanSerializerBase asArraySerializer() {
// already is one, so:
return this;
}
/*
/**********************************************************
/* JsonSerializer implementation that differs between impls
/**********************************************************
*/
// Re-defined from base class...
@Override
public void serializeWithType(Object bean, JsonGenerator jgen,
SerializerProvider provider, TypeSerializer typeSer)
throws IOException, JsonGenerationException
{
/* Should not even get here; but let's be nice and re-route
* if need be.
*/
_defaultSerializer.serializeWithType(bean, jgen, provider, typeSer);
}
/**
* Main serialization method that will delegate actual output to
* configured
* {@link BeanPropertyWriter} instances.
*/
@Override
public final void serialize(Object bean, JsonGenerator jgen, SerializerProvider provider)
throws IOException, JsonGenerationException
{
// [JACKSON-805]
if (provider.isEnabled(SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED)
&& hasSingleElement(provider)) {
serializeAsArray(bean, jgen, provider);
return;
}
/* note: it is assumed here that limitations (type id, object id,
* any getter, filtering) have already been checked; so code here
* is trivial.
*/
jgen.writeStartArray();
serializeAsArray(bean, jgen, provider);
jgen.writeEndArray();
}
/*
/**********************************************************
/* Field serialization methods
/**********************************************************
*/
private boolean hasSingleElement(SerializerProvider provider) {
final BeanPropertyWriter[] props;
if (_filteredProps != null && provider.getSerializationView() != null) {
props = _filteredProps;
} else {
props = _props;
}
return props.length == 1;
}
protected final void serializeAsArray(Object bean, JsonGenerator jgen, SerializerProvider provider)
throws IOException, JsonGenerationException
{
final BeanPropertyWriter[] props;
if (_filteredProps != null && provider.getSerializationView() != null) {
props = _filteredProps;
} else {
props = _props;
}
int i = 0;
try {
for (final int len = props.length; i < len; ++i) {
BeanPropertyWriter prop = props[i];
if (prop == null) { // can have nulls in filtered list; but if so, MUST write placeholders
jgen.writeNull();
} else {
prop.serializeAsColumn(bean, jgen, provider);
}
}
// NOTE: any getters can not be supported either
//if (_anyGetterWriter != null) {
// _anyGetterWriter.getAndSerialize(bean, jgen, provider);
//}
} catch (Exception e) {
String name = (i == props.length) ? "[anySetter]" : props[i].getName();
wrapAndThrow(provider, e, bean, name);
} catch (StackOverflowError e) {
JsonMappingException mapE = new JsonMappingException("Infinite recursion (StackOverflowError)", e);
String name = (i == props.length) ? "[anySetter]" : props[i].getName();
mapE.prependPath(new JsonMappingException.Reference(bean, name));
throw mapE;
}
}
/*
/**********************************************************
/* Standard methods
/**********************************************************
*/
@Override public String toString() {
return "BeanAsArraySerializer for "+handledType().getName();
}
}