io.r2dbc.spi

Interface Readable

All Known Subinterfaces:

OutParameters, Row

public interface Readable

Represents a readable object, for example a set of columns or OUT parameters from a database query, later on referred to as items. Values can for columns or OUT parameters be either retrieved by specifying a name or the index. Indexes are 0-based.

Column and OUT parameter names used as input to getter methods are case insensitive. When a get method is called with a name and several items have the same name, then the value of the first matching item will be returned. Items that are not explicitly named in the query should be referenced through indexes.

For maximum portability, items within each Readable should be read in left-to-right order, and each item should be read only once.

get(String) and get(int) without specifying a target type returns a suitable value representation. The R2DBC specification contains a mapping table that shows default mappings between database types and Java types. Specifying a target type, the R2DBC driver attempts to convert the value to the target type.

A item is invalidated after consumption.

Since:

0.9

See Also:

Row, OutParameters

Method Summary

Modifier and Type	Method and Description
default Object	get(int index) Returns the value using the default type mapping.
<T> T	get(int index, Class<T> type) Returns the value for a parameter.
default Object	get(String name) Returns the value for a parameter using the default type mapping.
<T> T	get(String name, Class<T> type) Returns the value.

Method Detail

get

@Nullable
default Object get(int index)

Returns the value using the default type mapping. The default implementation of this method calls get(int, Class) passing Object as the type to allow the implementation to make the loosest possible match.

Parameters:

index - the index of the parameter starting at 0

Returns:

the value. Value can be null.

Throws:

IndexOutOfBoundsException - if index if the index is out of range (negative or equals/exceeds the number of readable objects)

get

@Nullable
<T> T get(int index,
                    Class<T> type)

Returns the value for a parameter. Use Object to allow the implementation to make the loosest possible match.

Type Parameters:

T - the type of the item being returned.

Parameters:

index - the index starting at 0

type - the type of item to return. This type must be assignable to, and allows for variance.

Returns:

the value. Value can be null.

Throws:

IllegalArgumentException - if type is null

IndexOutOfBoundsException - if index is out of range (negative or equals/exceeds the number of readable objects)

get

@Nullable
default Object get(String name)

Returns the value for a parameter using the default type mapping. The default implementation of this method calls get(String, Class) passing Object as the type in order to allow the implementation to make the loosest possible match.

Parameters:

name - the name

Returns:

the value. Value can be null.

Throws:

IllegalArgumentException - if name is null

NoSuchElementException - if name is not a known readable column or out parameter

get

@Nullable
<T> T get(String name,
                    Class<T> type)

Returns the value. Use Object to allow the implementation to make the loosest possible match.

Type Parameters:

T - the type of the item being returned.

Parameters:

name - the name

type - the type of item to return. This type must be assignable to, and allows for variance.

Returns:

the value. Value can be null.

Throws:

IllegalArgumentException - if name or type is null

NoSuchElementException - if name is not a known readable column or out parameter