DeserializationFeature.java
package tools.jackson.databind;
import com.fasterxml.jackson.annotation.JacksonInject;
import tools.jackson.databind.cfg.ConfigFeature;
import tools.jackson.databind.cfg.MapperBuilder;
/**
* Enumeration that defines simple on/off features that affect
* the way Java objects are deserialized from JSON
*<p>
* Note that features can be set both through
* {@link ObjectMapper} (as sort of defaults) and through
* {@link ObjectReader}.
* In first case these defaults must follow "config-then-use" patterns
* (i.e. defined once, not changed afterwards); all per-call
* changes must be done using {@link ObjectReader}.
*<p>
* Note that features that do not indicate version of inclusion
* were available in Jackson 3.0 (or earlier); only later additions
* indicate version of inclusion.
*/
public enum DeserializationFeature implements ConfigFeature
{
/*
/**********************************************************************
/* Value (mostly scalar) mapping features
/**********************************************************************
*/
/**
* Feature that determines whether JSON floating point numbers
* are to be deserialized into {@link java.math.BigDecimal}s
* if only generic type description (either {@link Object} or
* {@link Number}, or within untyped {@link java.util.Map}
* or {@link java.util.Collection} context) is available.
* If enabled such values will be deserialized as {@link java.math.BigDecimal}s;
* if disabled, will be deserialized as {@link Double}s.
*<p>
* NOTE: one related aspect of {@link java.math.BigDecimal} handling that may need
* configuring is whether trailing zeroes are trimmed:
* {@link tools.jackson.databind.cfg.JsonNodeFeature#STRIP_TRAILING_BIGDECIMAL_ZEROES}
* is used for optionally enabling this for {@link tools.jackson.databind.JsonNode}
* values.
*<p>
* Feature is disabled by default, meaning that "untyped" floating
* point numbers will by default be deserialized as {@link Double}s
* (choice is for performance reason -- BigDecimals are slower than
* Doubles).
*/
USE_BIG_DECIMAL_FOR_FLOATS(false),
/**
* Feature that determines whether JSON integral (non-floating-point)
* numbers are to be deserialized into {@link java.math.BigInteger}s
* if only generic type description (either {@link Object} or
* {@link Number}, or within untyped {@link java.util.Map}
* or {@link java.util.Collection} context) is available.
* If enabled such values will be deserialized as
* {@link java.math.BigInteger}s;
* if disabled, will be deserialized as "smallest" available type,
* which is either {@link Integer}, {@link Long} or
* {@link java.math.BigInteger}, depending on number of digits.
* <p>
* Feature is disabled by default, meaning that "untyped" integral
* numbers will by default be deserialized using whatever
* is the most compact integral type, to optimize efficiency.
*/
USE_BIG_INTEGER_FOR_INTS(false),
/**
* Feature that determines how "small" JSON integral (non-floating-point)
* numbers -- ones that fit in 32-bit signed integer (`int`) -- are bound
* when target type is loosely typed as {@link Object} or {@link Number}
* (or within untyped {@link java.util.Map} or {@link java.util.Collection} context).
* If enabled, such values will be deserialized as {@link java.lang.Long};
* if disabled, they will be deserialized as "smallest" available type,
* {@link Integer}.
*<p>
* Note: if {@link #USE_BIG_INTEGER_FOR_INTS} is enabled, it has precedence
* over this setting, forcing use of {@link java.math.BigInteger} for all
* integral values.
*<p>
* Feature is disabled by default, meaning that "untyped" integral
* numbers will by default be deserialized using {@link java.lang.Integer}
* if value fits.
*/
USE_LONG_FOR_INTS(false),
/**
* Feature that determines whether JSON Array is mapped to
* <code>Object[]</code> or {@code List<Object>} when binding
* "untyped" objects (ones with nominal type of <code>java.lang.Object</code>).
* If true, binds as <code>Object[]</code>; if false, as {@code List<Object>}.
*<p>
* Feature is disabled by default, meaning that JSON arrays are bound as
* {@link java.util.List}s.
*/
USE_JAVA_ARRAY_FOR_JSON_ARRAY(false),
/**
* Feature that determines whether deserialization of "Reference Types"
* (such as {@link java.util.Optional}, {@link java.util.concurrent.atomic.AtomicReference},
* and Kotlin/Scala equivalents) should return Java {@code null} in case
* of value missing from incoming JSON. If disabled, reference type's
* "absent" value is returned (for example, {@link java.util.Optional#empty()}.
*<p>
* NOTE: this feature only affects handling of missing values; not explicit
* JSON {@code null}s.
* Also note that this feature only affects deserialization when reference value
* is passed via Creator (constructor or factory method) parameter; when
* Setter methods or fields are used, the reference type is left un-assigned
* (this is not specifically related to reference types, but general behavior).
*
* @since 3.1
*/
USE_NULL_FOR_MISSING_REFERENCE_VALUES(false),
/*
/**********************************************************************
/* Error handling features
/**********************************************************************
*/
/**
* Feature that determines whether encountering of unknown
* properties (ones that do not map to a property, and there is
* no "any setter" or handler that can handle it)
* should result in a failure (by throwing a
* {@link DatabindException}) or not.
* This setting only takes effect after all other handling
* methods for unknown properties have been tried, and
* property remains unhandled.
* Enabling this feature means that a {@link DatabindException}
* will be thrown if an unknown property is encountered.
*<p>
* Feature is disabled by default as of Jackson 3.0 (in 2.x it was enabled).
*/
FAIL_ON_UNKNOWN_PROPERTIES(false),
/**
* Feature that determines whether encountering of JSON null
* is an error when deserializing into Java primitive types
* (like 'int' or 'double'). If it is, a {@link DatabindException}
* is thrown to indicate this; if not, default value is used
* (0 for 'int', 0.0 for double, same defaulting as what JVM uses).
*<p>
* Feature is enabled by default as of Jackson 3.0 (in 2.x it was disabled).
*/
FAIL_ON_NULL_FOR_PRIMITIVES(true),
/**
* Feature that determines what happens when type of a polymorphic
* value (indicated for example by {@link com.fasterxml.jackson.annotation.JsonTypeInfo})
* cannot be found (missing) or resolved (invalid class name, non-mappable id);
* if enabled, an exception is thrown; if false, null value is used instead.
*<p>
* Feature is enabled by default so that exception is thrown for missing or invalid
* type information.
*/
FAIL_ON_INVALID_SUBTYPE(true),
/**
* Feature that determines what happens when reading JSON content into tree
* ({@link JsonNode} and a duplicate key
* is encountered (property name that was already seen for the JSON Object).
* If enabled, {@link DatabindException} will be thrown; if disabled, no exception
* is thrown and the new (later) value overwrites the earlier value.
*<p>
* Note that this property does NOT affect other aspects of data-binding; that is,
* no detection is done with respect to POJO properties or {@link java.util.Map}
* keys. New features may be added to control additional cases.
*<p>
* Feature is disabled by default so that no exception is thrown.
*/
FAIL_ON_READING_DUP_TREE_KEY(false),
/**
* Feature that determines what happens when a property that has been explicitly
* marked as ignorable is encountered in input: if feature is enabled,
* {@link DatabindException} is thrown; if false, property is quietly skipped.
*<p>
* Feature is disabled by default so that no exception is thrown.
*/
FAIL_ON_IGNORED_PROPERTIES(false),
/**
* Feature that determines what happens if an Object Id reference is encountered
* that does not refer to an actual Object with that id ("unresolved Object Id"):
* either an exception {@link tools.jackson.databind.deser.UnresolvedForwardReference}
* containing information about {@link tools.jackson.databind.deser.UnresolvedId}
* is thrown (<code>true</code>), or a null object is used instead (<code>false</code>).
* Note that if this is set to <code>false</code>, no further processing is done;
* specifically, if reference is defined via setter method, that method will NOT
* be called.
*<p>
* Feature is enabled by default, so that unknown Object Ids will result in an
* exception being thrown, at the end of deserialization.
*/
FAIL_ON_UNRESOLVED_OBJECT_IDS(true),
/**
* Feature that determines what happens if one or more Creator properties (properties
* bound to parameters of Creator method (constructor or static factory method))
* are missing value to bind to from content.
* If enabled, such missing values result in a {@link DatabindException} being
* thrown with information on the first one (by index) of missing properties.
* If disabled, and if property is NOT marked as required,
* missing Creator properties are filled
* with <code>null values</code> provided by deserializer for the type of parameter
* (usually null for Object types, and default value for primitives; but redefinable
* via custom deserializers).
*<p>
* Note that having an injectable value counts as "not missing".
*<p>
* Feature is disabled by default, so that no exception is thrown for missing creator
* property values, unless they are explicitly marked as `required`.
*/
FAIL_ON_MISSING_CREATOR_PROPERTIES(false),
/**
* Feature that determines what happens if one or more Creator properties (properties
* bound to parameters of Creator method (constructor or static factory method))
* are bound to null values - either from the JSON or as a default value. This
* is useful if you want to avoid nulls in your codebase, and particularly useful
* if you are using Java or Scala {@code Optional}s for non-mandatory fields.
* Feature is disabled by default, so that no exception is thrown for missing creator
* property values, unless they are explicitly marked as `required`.
*/
FAIL_ON_NULL_CREATOR_PROPERTIES(false),
/**
* Feature that determines what happens when a property annotated with
* {@link com.fasterxml.jackson.annotation.JsonTypeInfo.As#EXTERNAL_PROPERTY} is missing,
* but associated type id is available. If enabled, a {@link DatabindException} is always
* thrown when property value is missing (if type id does exist);
* if disabled, exception is only thrown if property is marked as {@code required}.
*<p>
* Feature is enabled by default, so that exception is thrown when a subtype property is
* missing.
*/
FAIL_ON_MISSING_EXTERNAL_TYPE_ID_PROPERTY(true),
/**
* Feature that determines behavior for data-binding after binding the root value.
* If feature is enabled, one more call to
* {@link tools.jackson.core.JsonParser#nextToken} is made to ensure that
* no more tokens are found (and if any is found,
* {@link tools.jackson.databind.exc.MismatchedInputException} is thrown); if
* disabled, no further checks are made.
*<p>
* Feature could alternatively be called {@code READ_FULL_STREAM}, since it
* effectively verifies that input stream contains only as much data as is needed
* for binding the full value, and nothing more (except for possible ignorable
* white space or comments, if supported by data format).
*<p>
* NOTE: this feature should usually be disabled when reading from
* {@link java.io.DataInput}, since it cannot detect end-of-input efficiently
* (but by throwing an {@link java.io.IOException}). Disabling is NOT done
* automatically by Jackson: users are recommended to disable it.
*<p>
* Feature is enabled by default as of Jackson 3.0 (in 2.x it was disabled).
*/
FAIL_ON_TRAILING_TOKENS(true),
/**
* Feature that determines behavior when deserializing polymorphic types that use
* Class-based Type Id mechanism (either
* {@code JsonTypeInfo.Id.CLASS} or {@code JsonTypeInfo.Id.MINIMAL_CLASS}):
* If enabled, an exception will be
* thrown if a subtype (Class) is encountered that has not been explicitly registered (by
* calling {@link MapperBuilder#registerSubtypes} or using annotation
* {@link com.fasterxml.jackson.annotation.JsonSubTypes}).
*<p>
* Note that for Type Name - based Type Id mechanism ({@code JsonTypeInfo.Id.NAME})
* you already need to register the subtypes but with so this feature has no effect.
*<p>
* Feature is disabled by default.
*/
FAIL_ON_SUBTYPE_CLASS_NOT_REGISTERED(false),
/**
* Feature that determines whether Jackson code should catch
* and wrap non-Jackson {@link Exception}s (but never {@link Error}s!)
* to add additional information about
* location (within input) of problem or not. If enabled,
* most exceptions will be caught and re-thrown; this can be
* convenient both in that all exceptions will be checked and
* declared, and so there is more contextual information.
* However, sometimes calling application may just want "raw"
* unchecked exceptions passed as is.
*<p>
* NOTE: most of the time exceptions that may or may not be wrapped are of
* type {@link RuntimeException}: as mentioned earlier,
* {@link tools.jackson.core.JacksonException}s) will
* always be passed as-is.
*<p>
* Disabling this feature will mean that you will need to adjust your try/catch
* blocks to properly handle {@link RuntimeException}s. Failing to do so,
* may cause your application to crash due to unhandled exceptions.
*<p>
* Feature is enabled by default.
*/
WRAP_EXCEPTIONS(true),
/**
* Feature that determines the handling of properties not included in the active JSON view
* during deserialization.
*<p>
* When enabled, if a property is encountered during deserialization that is not part of the
* active view (as defined by {@link com.fasterxml.jackson.annotation.JsonView}),
* an exception is thrown. If disabled, the property is simply ignored.
*<p>
* This feature is particularly useful in scenarios where strict adherence to the specified
* view is required and any deviation, such as the presence of properties not belonging to
* the view, should be reported as an error. It can enhance the robustness of data binding
* by ensuring that only the properties relevant to the active view are considered during
* deserialization, thereby preventing unintended data from being processed.
*<p>
* Feature is disabled by default to maintain backward compatibility.
*/
FAIL_ON_UNEXPECTED_VIEW_PROPERTIES(false),
/**
* Feature that determines the handling of injected properties during deserialization.
*<p>
* When enabled, if an injected property without matching value is encountered
* during deserialization, an exception is thrown.
* When disabled, no exception is thrown.
* See {@link JacksonInject#optional()} for per-property override
* of this setting.
*<p>
* This feature is enabled by default to maintain backwards-compatibility.
*
* @see JacksonInject#optional()
*/
FAIL_ON_UNKNOWN_INJECT_VALUE(true),
/*
/**********************************************************************
/* Structural conversion features
/**********************************************************************
*/
/**
* Feature that determines whether it is acceptable to coerce non-array
* (in JSON) values to work with Java collection (arrays, java.util.Collection)
* types. If enabled, collection deserializers will try to handle non-array
* values as if they had "implicit" surrounding JSON array.
* This feature is meant to be used for compatibility/interoperability reasons,
* to work with packages (such as XML-to-JSON converters) that leave out JSON
* array in cases where there is just a single element in array.
*<p>
* Feature is disabled by default.
*/
ACCEPT_SINGLE_VALUE_AS_ARRAY(false),
/**
* Feature that determines whether it is acceptable to coerce single value array (in JSON)
* values to the corresponding value type. This is basically the opposite of the {@link #ACCEPT_SINGLE_VALUE_AS_ARRAY}
* feature. If more than one value is found in the array, a {@link DatabindException} is thrown.
* <p>
* NOTE: only <b>single</b> wrapper Array is allowed: if multiple attempted, exception
* will be thrown.
* <p>
* Feature is disabled by default.
*/
UNWRAP_SINGLE_VALUE_ARRAYS(false),
/**
* Feature to allow "unwrapping" root-level JSON value, to match setting of
* {@link SerializationFeature#WRAP_ROOT_VALUE} used for serialization.
* Will verify that the root JSON value is a JSON Object, and that it has
* a single property with expected root name. If not, a
* {@link DatabindException} is thrown; otherwise value of the wrapped property
* will be deserialized as if it was the root value.
* <p>
* Feature is disabled by default.
*/
UNWRAP_ROOT_VALUE(false),
/*
/**********************************************************************
/* Value conversion/coercion features
/**********************************************************************
*/
/**
* Feature that can be enabled to allow JSON empty String
* value ({@code ""}) to be bound as {@code null} for POJOs and other structured
* values ({@link java.util.Map}s, {@link java.util.Collection}s).
* If disabled, standard POJOs can only be bound from JSON {@code null} or
* JSON Object (standard meaning that no custom deserializers or
* constructors are defined; both of which can add support for other
* kinds of JSON values); if enabled, empty JSON String can be taken
* to be equivalent of JSON null.
*<p>
* NOTE: this does NOT apply to scalar values such as Strings, booleans, numbers
* and date/time types;
* whether these can be coerced depends on
* {@link MapperFeature#ALLOW_COERCION_OF_SCALARS}.
*<p>
* Feature is disabled by default.
*/
ACCEPT_EMPTY_STRING_AS_NULL_OBJECT(false),
/**
* Feature that can be enabled to allow empty JSON Array
* value (that is, {@code [ ]} to be bound to POJOs {@code null}.
* If disabled, standard POJOs can only be bound from JSON {@code null} or
* JSON Object (standard meaning that no custom deserializers or
* constructors are defined; both of which can add support for other
* kinds of JSON values); if enabled, empty JSON Array will be taken
* to be equivalent of JSON {@code null}.
*<p>
* Feature is disabled by default.
*/
ACCEPT_EMPTY_ARRAY_AS_NULL_OBJECT(false),
/**
* Feature that determines whether coercion from JSON floating point
* number (anything with command (`.`) or exponent portion (`e` / `E'))
* to an expected integral number (`int`, `long`, `java.lang.Integer`, `java.lang.Long`,
* `java.math.BigDecimal`) is allowed or not.
* If enabled, coercion truncates value; if disabled, a {@link DatabindException}
* will be thrown.
*<p>
* Feature is enabled by default.
*/
ACCEPT_FLOAT_AS_INT(true),
/*
/**********************************************************************
/* Other
/**********************************************************************
*/
/**
* Feature that determines whether {@link ObjectReader} should
* try to eagerly fetch necessary {@link ValueDeserializer} when
* possible. This improves performance in cases where similarly
* configured {@link ObjectReader} instance is used multiple
* times; and should not significantly affect single-use cases.
*<p>
* Note that there should not be any need to normally disable this
* feature: only consider that if there are actual perceived problems.
*<p>
* Feature is enabled by default.
*/
EAGER_DESERIALIZER_FETCH(true)
;
private final boolean _defaultState;
private final int _mask;
private DeserializationFeature(boolean defaultState) {
_defaultState = defaultState;
_mask = (1 << ordinal());
}
@Override
public boolean enabledByDefault() { return _defaultState; }
@Override
public int getMask() { return _mask; }
@Override
public boolean enabledIn(int flags) { return (flags & _mask) != 0; }
}