com.electronwill.nightconfig.core.serde.annotations

Annotation Type SerdeAssert

@Repeatable(value=SerdeAssertsContainer.class)
 @Retention(value=RUNTIME)
 @Target(value=FIELD)
public @interface SerdeAssert

Throw an exception if the annotated field does not match the given condition.

Example: rejecting null fields

 import com.electronwill.nightconfig.core.serde.annotations.SerdeAssert;
 import com.electronwill.nightconfig.core.serde.annotations.SerdeAssert.AssertThat;

 class MyObject {
                 @SerdeAssert(AssertThat.NOT_NULL)
                String nonNull;
 }
 

When is the assertion applied?

Assertions defined with @SerdeAssert are always applied on the value of the java field. If the field's value is replaced by a default value, the assertions are applied on the default value.

• When deserializing: after the deserialization of the value from the config, after the resolution of the default value (if any).
• When serializing: before the serialization of the value to the config, after the resolution of the default value (if any).

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
SerdeAssert.AssertThat[]	value One or multiple assertions to check.

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 (de)serializing satisfies a condition.
java.lang.Class<?>	customClass The class where to find the custom assertion predicate.
SerdePhase	phase Controls whether the assert value applies when Serializing and/or Deserializing.

Element Detail

value

public abstract SerdeAssert.AssertThat[] value

One or multiple assertions to check.

If multiple assertions are specified, they are combined with a logical AND, that is, they must all be true for the assertion to succeed.

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 assertion 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 assertion 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 (de)serializing satisfies a condition. The predicate is applied on the field's value.

Constraints on methods

The predicate method must take exactly one parameter of type T, where T is the type of the field to (de)serialize. 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<T>, where T is the type of the field to (de)serialize. 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 assertion predicate

See Also:

Predicate

Default:

""

phase

public abstract SerdePhase phase

Controls whether the assert value applies when Serializing and/or Deserializing.

Returns:

the phase during which the assert condition should be checked

Default:

com.electronwill.nightconfig.core.serde.annotations.SerdePhase.BOTH