fastjson2/docs/features_en.md

Configure serialization and deserialization with Features

1. Feature Introduction

In fastjson 2.x, there are two Features, which are used to configure the behavior of serialization and deserialization respectively

• JSONWriter.Feature Configure serialization behavior
• JSONReader.Feature Configure deserialization behavior

2. Using Feature in JSON toJSONString and parseObject methods

2.1 Using JSONWriter.Feature in JSON toJSONString method

Bean bean=...;
        JSON.toJSONString(bean,JSONWriter.Feature.WriteNulls); // Fields in the output object whose value is null

2.2 Using JSONReader.Feature in JSON parseObject method

String jsonStr=...;
        JSON.parseObject(jsonStr,JSONReader.Feature.UseBigDecimalForDoubles); // Read decimal value as double

3. Configure Features on JSONField and JSONType

class Model {
    @JSONField(serializeFeatures = JSONWriter.Feature.BrowserCompatible)
    public long value;
}
***

4. JSONReader.Feature

JSONReader.Feature	Description
FieldBased	Field-based deserialization. If not configured, it will be serialized based on public field and getter methods by default. After configuration, it will be deserialized based on non-static fields (including private). It will be safer under FieldBased configuration.
IgnoreNoneSerializable	Deserialization ignores fields of non-Serializable types.
SupportArrayToBean	Ways to support data mapping.
InitStringFieldAsEmpty	Initialize the String field to the empty string, e.g: "".
SupportAutoType	Automatic type is supported. To read JSON data with "@type" type information, you need to open SupportAutoType explicitly.
SupportSmartMatch	The default is camel case exact match, after opening this, it can intelligently identify the case in camel/upper/pascal/snake/Kebab.
UseNativeObject	The default is to use JSONObject and JSONArray, and LinkedHashMap and ArrayList will be used after configuration.
SupportClassForName	To support fields of type Class, use Class.forName. This is disabled by default for security.
IgnoreSetNullValue	Fields with null input are ignored.
UseDefaultConstructorAsPossible	Use the default constructor as much as possible, and use Unsafe.allocateInstance to implement this option when fieldBase is turned on and this option is not turned on.
UseBigDecimalForFloats	The default configuration will use BigDecimal to parse decimals, and will use Float when turned on.
UseBigDecimalForDoubles	The default configuration will use BigDecimal to parse decimals, and Double will be used when turned on.
ErrorOnEnumNotMatch	By default, if the name of the Enum does not match, it will be ignored, and an exception will be thrown if it does not match when turned on.
TrimString
ErrorOnNotSupportAutoType
DuplicateKeyValueAsArray
AllowUnQuotedFieldNames
NonStringKeyAsString
Base64StringAsByteArray

5. JSONWriter.Feature

JSONWriter.Feature	Description
FieldBased	Field-based deserialization. If not configured, it will be serialized based on public field and getter methods by default. After configuration, it will be deserialized based on non-static fields (including private).
IgnoreNoneSerializable	Serialization ignores fields of non-Serializable types.
BeanToArray	Sequence the objects into an array format like [101,"XX"], which will be smaller.
WriteNulls	Serialize write null field
BrowserCompatible	Over a wide range of integers than JavaScript supports, the output is in string format.
NullAsDefaultValue	The null value is output as the default value, the null of the Number type is output as 0, the null output of the String type is "", and the output of the array and Collection type is [].
WriteBooleanAsNumber	Write true as 1 and false as 0.
WriteNonStringValueAsString	Write values of non-String types as Strings, excluding objects and data types.
WriteClassName	Write type information when serializing.
NotWriteRootClassName	When WriteClassName is turned on, the type information of the root object is not output.
NotWriteHashMapArrayListClassName	When WriteClassName is opened, the type information of objects of type HashMap/ArrayList is not output, and the deserialization combined with UseNativeObject can save the size of the serialized result.
NotWriteDefaultValue	When the value of the field is the default value, it is not output, which can save the size of the serialized result.
WriteEnumsUsingName	Serialize enum using name.
WriteEnumUsingToString	Serialize enum using toString method.
IgnoreErrorGetter	Error ignoring Getter methods
PrettyFormat	formatted json string.
ReferenceDetection	Turn on reference detection, which is turned off by default, which is inconsistent with fastjson 1.x.
WriteNameAsSymbol	Output field names as symbols, this only works under JSONB.
WriteBigDecimalAsPlain	Serialize BigDecimal using toPlainString, avoiding scientific notation.
UseSingleQuotes
MapSortField
WriteNullListAsEmpty
WriteNullStringAsEmpty
WriteNullNumberAsZero
WriteNullBooleanAsFalse
NotWriteEmptyArray
WriteNonStringKeyAsString
ErrorOnNoneSerializable
WritePairAsJavaBean
LargeObject	This is a protection measure to prevent serialization of circular reference objects from consuming excessive resources.