com.electronwill.nightconfig.core.serde.annotations

Annotation Type SerdeSkipDeserializingIf

@Retention(value=RUNTIME)
 @Target(value=FIELD)
public @interface SerdeSkipDeserializingIf

Don't deserialize the annotated field if some condition is true.

Example: preserving fields if the config entry is missing

 class MyObject {
      @SerdeSkipSerializingIf(SkipDeIf.IS_MISSING)
     String name;
 }
 

Example: skipping empty lists

 class MyObject {
      @SerdeSkipSerializingIf(SkipDeIf.IS_EMPTY)
      List<String> servers;
 }
 

Example: combining multiple conditions

 class MyObject {
     // The field will not be modified if the config value is missing or null.
      @SerdeSkipSerializingIf({SkipDeIf.IS_MISSING, SkipDeIf.IS_NULL})
     String name;
 }
 

Advanced example: skipping a field based on a custom condition

 class MyObject {
      @SerdeSkipSerializingIf(value = SkipDeIf.CUSTOM, customCheck="skipName")
     String name;

     private boolean skipName(Object nameInConfig) {
         return nameInConfig == null ||
             nameInConfig == NullObject.NULL_OBJECT ||
             nameInConfig.equals("skip me");
     }
 }
 

Advanced example: skipping a field based on a custom condition defined in another class

 class MyObject {
      @SerdeSkipSerializingIf(value = {SkipDeIf.CUSTOM}, customClass=SkipChecker.class, customCheck="skipName")
     String name;

      @SerdeSkipSerializingIf(value = {SkipDeIf.CUSTOM}, customClass=SkipChecker.class, customCheck="skipId")
     int id;
 }

 class SkipChecker {
     // The predicate can be defined by a `Predicate` field too!
      static final Predicate<Object> skipName = nameInConfig -> nameInConfig == null ||
 	       nameInConfig == NullObject.NULL_OBJECT ||
         nameInConfig.equals("skip me");
     

     // Note that skip predicates defined in another class must be static.
     static boolean skipId(Object idInConfig) {
               return idInConfig instanceof Integer  && ((int)idInConfig) == -1;
     }
 }
 

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
SerdeSkipDeserializingIf.SkipDeIf[]	value The type of skip predicate: either a predefined condition, or CUSTOM.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
java.lang.String	customCheck The name of the field or method that defines the predicate to apply in order to test whether the field that we are deserializing should be skipped.
java.lang.Class<?>	customClass The class where to find the custom skip predicate.

Element Detail

value

public abstract SerdeSkipDeserializingIf.SkipDeIf[] value

The type of skip predicate: either a predefined condition, or CUSTOM.

If set to CUSTOM, you must provide the customCheck() parameter, and you may provide the customClass() parameter.

customClass

public abstract java.lang.Class<?> customClass

The class where to find the custom skip predicate.

By default, it is set to Object.class, which is treated as a special value. It means that the actual class to use is the one of the object that is currently being (de)serialized.

Returns:

the class that defines the skip predicate

See Also:

customCheck()

Default:

java.lang.Object.class

customCheck

public abstract java.lang.String customCheck

The name of the field or method that defines the predicate to apply in order to test whether the field that we are deserializing should be skipped. The predicate is applied on the raw config value, as returned by UnmodifiableConfig.getRaw(java.util.List).

Constraints on methods

The predicate method must take exactly one parameter of type Object. If customClass() is set to its non-default value, the method must be static.

Constraints on fields

The predicate field must be of type java.util.function.Predicate<Object>. In most cases, the predicate field should be declared with the transient keyword, to prevent it from being (de)serialized.

Returns:

the name of the skip predicate

See Also:

Predicate

Default:

""