Interface DbColumn

All Superinterfaces:

OptionalValue<Object>, Value<Object>

All Known Implementing Classes:

DbColumnBase, MongoDbColumn

public interface DbColumn
extends OptionalValue<Object>

Column data and metadata.

Column may represent a null value. Get methods on this class would throw an exception if the value is null, use Value.asOptional(), or one of the mapping methods that support optional values, such as OptionalValue.ifPresent(java.util.function.Consumer) to consume such columns.

Method Summary

Modifier and Type	Method	Description
String	dbType()	Type of the column in the language of the database.
default Object	get()	Untyped value of this column, returns java type as provided by the underlying database driver.
<T> T	get(GenericType<T> type)	Value of this column as a generic type.
<T> T	get(Class<T> type)	Typed value of this column.
Class<?>	javaType()	Type of the column as would be returned by the underlying database driver.
String	name()	Column name.
default Optional<Integer>	precision()	Precision of this column.
default Optional<Integer>	scale()	Scale of this column.

Methods inherited from interface OptionalValue

as, as, as, asBoolean, asDouble, asInt, asLong, asString, ifPresent, ifPresentOrElse, isEmpty, isPresent, map, or, orElse, orElseGet, orElseThrow, orElseThrow

Modifier and Type	Method	Description
<N> OptionalValue<N>	as(GenericType<N> type)	Convert this value to a different type using a mapper.
<N> OptionalValue<N>	as(Class<N> type)	Convert this value to a different type using a mapper.
<N> OptionalValue<N>	as(Function<? super Object, ? extends N> mapper)	Convert this Value to a different type using a mapper function.
default OptionalValue<Boolean>	asBoolean()	Boolean typed value.
default OptionalValue<Double>	asDouble()	Double typed value.
default OptionalValue<Integer>	asInt()	Integer typed value.
default OptionalValue<Long>	asLong()	Long typed value.
default OptionalValue<String>	asString()	String typed value.
default void	ifPresent(Consumer<? super Object> consumer)	If a value is present, invoke the specified consumer with the value, otherwise do nothing.
default void	ifPresentOrElse(Consumer<Object> action, Runnable emptyAction)	If a value is present, performs the given action with the value, otherwise performs the given empty-based action.
default boolean	isEmpty()	Return false if there is a value present, otherwise true.
default boolean	isPresent()	Return true if there is a value present, otherwise false.
default <U> Optional<U>	map(Function<? super Object, ? extends U> mapper)	If a value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result.
default Optional<Object>	or(Supplier<? extends Optional<Object>> supplier)	If the underlying Optional does not have a value, set it to the Optional produced by the supplying function.
default Object	orElse(Object other)	Return the value if present, otherwise return other.
default Object	orElseGet(Supplier<? extends Object> other)	Return the value if present, otherwise invoke other and return the result of that invocation.
default Object	orElseThrow()	If a value is present, returns the value, otherwise throws NoSuchElementException.
default <X extends Throwable> Object	orElseThrow(Supplier<? extends X> exceptionSupplier)	Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.

Methods inherited from interface Value

asOptional, filter, flatMap, getBoolean, getDouble, getInt, getLong, getString, stream

Modifier and Type	Method	Description
Optional<Object>	asOptional()	Typed value as Optional.
default Optional<Object>	filter(Predicate<? super Object> predicate)	If a value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an empty Optional.
default <U> Optional<U>	flatMap(Function<? super Object, Optional<? extends U>> mapper)	Apply the provided Optional-bearing mapping function to this value, return that result.
default boolean	getBoolean()	Boolean typed value.
default double	getDouble()	Double typed value.
default int	getInt()	Integer typed value.
default long	getLong()	Long typed value.
default String	getString()	String typed value.
default Stream<Object>	stream()	If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

Method Details

get

<T> T get(Class<T> type)
   throws MapperException

Typed value of this column. This method can return a correct result only if the type is the same as javaType() or there is a Mapper registered that can map it.

Specified by:

get in interface Value<Object>

Type Parameters:

T - type of the returned value

Parameters:

type - class of the type that should be returned (must be supported by the underlying data type)

Returns:

value of this column correctly typed

Throws:

MapperException - in case the type is not the underlying javaType() and there is no mapper registered for it

get

<T> T get(GenericType<T> type)
   throws MapperException

Value of this column as a generic type. This method can return a correct result only if the type represents a class, or if there is a Mapper registered that can map underlying javaType() to the type requested.

Specified by:

get in interface Value<Object>

Type Parameters:

T - type of the returned value

Parameters:

type - requested type

Returns:

value mapped to the expected type if possible

Throws:

MapperException - in case the mapping cannot be done

get

default Object get()

Untyped value of this column, returns java type as provided by the underlying database driver.

WARNING: for backward compatibility, this method MAY return null if the underlying column value is null. As this is not aligned with Helidon APIs, which forbid returns of null, this will change in future versions. If you need support for nullable columns, use the optional-like methods on this type, such as OptionalValue.isEmpty(), OptionalValue.isPresent(), OptionalValue.ifPresent(java.util.function.Consumer) etc. to handle {code null} values.

Specified by:

get in interface OptionalValue<Object>

Specified by:

get in interface Value<Object>

Returns:

value of this column

javaType

Class<?> javaType()

Type of the column as would be returned by the underlying database driver.

Returns:

class of the type

See Also:

• dbType()

dbType

String dbType()

Type of the column in the language of the database.

Example for SQL - if a column is declared as VARCHAR(256) in the database, this method would return VARCHAR and method javaType() would return String.

Returns:

column type as the database understands it

name

String name()

Column name.

Specified by:

name in interface Value<Object>

Returns:

name of this column

precision

default Optional<Integer> precision()

Precision of this column.

Precision depends on data type:

• Numeric: The maximal number of digits of the number
• String/Character: The maximal length
• Binary: The maximal number of bytes
• Other: Implementation specific

Returns:

precision of this column or empty if precision is not available

scale

default Optional<Integer> scale()

Scale of this column.

Scale is the number of digits in a decimal number to the right of the decimal separator.

Returns:

scale of this column or empty if scale is not available