AttributeValue (Structure API 17.24.0 API)

Object
- AttributeValue<T>

Type Parameters:

T - type of the value object
```
@PublicApi
 @Immutable
public abstract class AttributeValue<T>
extends Object
```
Represents a value, or lack thereof. A defined value must be non-null. Similar to Optional<T>, but with additional values to represent special cases and an additional field to carry loader data.

AttributeValue instances are immutable.

Loader data

Loader data is a field that attribute loaders can use to store additional information, which is not a part of the resulting value, but which can be used by some other loaders or by the same loader when calculating a multi-row value.

For example, a loader that calculates the sum of all story points under the row without the row itself could store the own story points value in the loader data, because it will be needed when calculating the attribute value for the parent.

Special values

Special values are provided via the static methods and represent a few special situations. See undefined(), absent(), inaccessible() and error(). Special values may also carry loader data.

Since:

17.0

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> AttributeValue<T>`	`absent()` Returns an "absent" undefined value, which is used as a placeholder for a value that is being calculated.
`<X> AttributeValue<X>`	`cast(AttributeSpec<X> spec)` Transforms the value to a different type.
`static <T> AttributeValue<T>`	`error()` Returns an "error" undefined value.
`T`	`getDefinedValue()` Returns a defined value, or throws a runtime exception if the value is not defined.
`<D> D`	`getLoaderData(Class<D> valueClass)` Returns the loader data if it matches the provided type.
`abstract T`	`getValue()` Returns the value or `null` if this value is undefined.
`abstract AttributeValue<T>`	`ifPresent(Consumer<? super T> consumer)` Supplies the value to the consumer, if the value is defined.
`static <T> AttributeValue<T>`	`inaccessible()` Returns an "inaccessible" undefined value, which means the row is not accessible to the user and the real value is not available.
`abstract boolean`	`isAbsent()` Checks if this is a special "absent" value.
`abstract boolean`	`isDefined()` Checks if the value is defined.
`abstract boolean`	`isError()` Checks if this is a special "error" value.
`abstract boolean`	`isInaccessible()` Checks if this is a special "inaccessible" value.
`static <T> AttributeValue<T>`	`of(T value)` Creates an instance for the given value.
`static <T> AttributeValue<T>`	`ofNullable(T value)` Creates an instance for the given value.
`static <T> AttributeValue<T>`	`undefined()` Returns an undefined value.
`abstract AttributeValue<T>`	`withData(Object loaderData)` Creates a new instance of `AttributeValue` that has the same value, but a new loader data.

Methods inherited from class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - of
```
@NotNull
public static <T> AttributeValue<T> of(@NotNull
                                                T value)
```
    Creates an instance for the given value.
    
    Type Parameters:
    
    T - value type
    
    Parameters:
    
    value - a value
    
    Returns:
    
    attribute value instance
  - ofNullable
```
@NotNull
public static <T> AttributeValue<T> ofNullable(@Nullable
                                                        T value)
```
    Creates an instance for the given value. If the value is null, returns an undefined value.
    
    Type Parameters:
    
    T - value type
    
    Parameters:
    
    value - a value or null
    
    Returns:
    
    attribute value instance
  - undefined
```
@NotNull
public static <T> AttributeValue<T> undefined()
```
    Returns an undefined value.
    
    Type Parameters:
    
    T - value type
    
    Returns:
    
    undefined value
  - error
```
@NotNull
public static <T> AttributeValue<T> error()
```
    Returns an "error" undefined value. It means there was an error when calculating the value. Specific loaders may put additional information about the error as loader data.
    
    Type Parameters:
    
    T - value type
    
    Returns:
    
    error value
  - absent
```
@Internal
 @NotNull
public static <T> AttributeValue<T> absent()
```
    Returns an "absent" undefined value, which is used as a placeholder for a value that is being calculated. This method should not be used outside the Attributes system.
    
    Type Parameters:
    
    T - value type
    
    Returns:
    
    absent value
  - inaccessible
```
@Internal
 @NotNull
public static <T> AttributeValue<T> inaccessible()
```
    Returns an "inaccessible" undefined value, which means the row is not accessible to the user and the real value is not available. This method should not be used outside the Attributes system.
    
    Type Parameters:
    
    T - value type
    
    Returns:
    
    inaccessible value
  - withData
```
@NotNull
public abstract AttributeValue<T> withData(@Nullable
                                                    Object loaderData)
```
    Creates a new instance of AttributeValue that has the same value, but a new loader data.
    
    Parameters:
    
    loaderData - loader data
    
    Returns:
    
    a new attribute value
  - getValue
```
@Nullable
public abstract T getValue()
```
    Returns the value or null if this value is undefined.
    
    Returns:
    
    value
  - getDefinedValue
```
@NotNull
public final T getDefinedValue()
```
    Returns a defined value, or throws a runtime exception if the value is not defined.
    
    Returns:
    
    value
    
    Throws:
    
    StructureRuntimeException - if the value is undefined
  - ifPresent
```
@NotNull
public abstract AttributeValue<T> ifPresent(@NotNull
                                                     Consumer<? super T> consumer)
```
    Supplies the value to the consumer, if the value is defined.
    
    Parameters:
    
    consumer - consumer of the value, will be supplied with a non-null reference
    
    Returns:
    
    this instance
  - isDefined
```
public abstract boolean isDefined()
```
    Checks if the value is defined.
    
    Returns:
    
    true if the value is defined
  - isError
```
public abstract boolean isError()
```
    Checks if this is a special "error" value.
    
    Returns:
    
    true if this is an error
  - isAbsent
```
public abstract boolean isAbsent()
```
    Checks if this is a special "absent" value.
    
    Returns:
    
    true if this is an absent value
  - isInaccessible
```
public abstract boolean isInaccessible()
```
    Checks if this is a special "inaccessible" value.
    
    Returns:
    
    true if this is an inaccessible value
  - getLoaderData
```
@Nullable
public <D> D getLoaderData(Class<D> valueClass)
```
    Returns the loader data if it matches the provided type.
    
    Type Parameters:
    
    D - expected loader data type
    
    Parameters:
    
    valueClass - expected loader data class
    
    Returns:
    
    loader data or null if it is missing or of other type
  - cast
```
@NotNull
 @Internal
public <X> AttributeValue<X> cast(AttributeSpec<X> spec)
```
    Transforms the value to a different type.
    
    Type Parameters:
    
    X - the new type
    
    Parameters:
    
    spec - attribute spec to take the type from
    
    Returns:
    
    this instance

Class AttributeValue<T>

Loader data

Special values

Method Summary

Methods inherited from class Object

Method Detail

of

ofNullable

undefined

error

absent

inaccessible

withData

getValue

getDefinedValue

ifPresent

isDefined

isError

isAbsent

isInaccessible

getLoaderData

cast