tech.ydb.core

Interface Result<T>

Type Parameters:

T - type of result value

All Known Implementing Classes:

Result.Error, Result.Fail, Result.Success, Result.Unexpected

public interface Result<T>

Author:

Sergey Polovko, Alexandr Gorshenin

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Result.Error<V>
static class	Result.Fail<V>
static class	Result.Success<V>
static class	Result.Unexpected<V>

Method Summary

Modifier and Type	Method and Description
static <T,U> Function<Result<T>,CompletableFuture<Result<U>>>	compose(Function<T,CompletableFuture<Result<U>>> mapper) Create functor to compose the successful result to next completable future with another result.
static <T> Function<Result<T>,CompletableFuture<Status>>	composeStatus(Function<T,CompletableFuture<Status>> mapper) Create functor to compose the successful result to next completable future with status.
static <T,U> Function<Result<T>,CompletableFuture<Result<U>>>	composeValue(U value) Create functor to compose the successful result to completed future with specified value.
static <V> Result<V>	error(String message, Throwable throwable)
static <V> Result<V>	fail(Status status)
static <V> Result<V>	fail(UnexpectedResultException unexpected)
Status	getStatus()
T	getValue()
default boolean	isSuccess()
<U> Result<U>	map(Function<T,U> mapper)
<U> CompletableFuture<Result<U>>	mapResultFuture(Function<T,CompletableFuture<Result<U>>> mapper)
CompletableFuture<Status>	mapStatusFuture(Function<T,CompletableFuture<Status>> mapper)
static <V> Result<V>	success(V value)
static <V> Result<V>	success(V value, Status status)

Method Detail

getStatus

@Nonnull
Status getStatus()

getValue

@Nonnull
T getValue()
             throws UnexpectedResultException

Throws:

UnexpectedResultException

map

@Nonnull
<U> Result<U> map(Function<T,U> mapper)

mapResultFuture

@Nonnull
<U> CompletableFuture<Result<U>> mapResultFuture(Function<T,CompletableFuture<Result<U>>> mapper)

mapStatusFuture

@Nonnull
CompletableFuture<Status> mapStatusFuture(Function<T,CompletableFuture<Status>> mapper)

isSuccess

default boolean isSuccess()

success

static <V> Result<V> success(@Nonnull
                             V value)

success

static <V> Result<V> success(@Nonnull
                             V value,
                             Status status)

fail

static <V> Result<V> fail(@Nonnull
                          Status status)

fail

static <V> Result<V> fail(UnexpectedResultException unexpected)

error

static <V> Result<V> error(String message,
                           Throwable throwable)

compose

static <T,U> Function<Result<T>,CompletableFuture<Result<U>>> compose(Function<T,CompletableFuture<Result<U>>> mapper)

Create functor to compose the successful result to next completable future with another result. Failed results will be passed as is.

This helper is designed to be used as CompletableFuture.thenCompose(java.util.function.Function) argument

Example of usage:

 
 // Execute one query, with opening new transaction
 session.executeDataQuery(...)
    // Execute second query if first was successful
    .thenCompose(Result.compose(fisrt -> session.executeDataQuery(...)))
    // Commit transaction after two successful query executions
    .thenCompose(Result.composeStatus(second -> session.commitTransaction(...)));
 

Type Parameters:

T - type of value in Result

U - type of resulting value in returning future

Parameters:

mapper - mapper from successful value to completable future with another result

Returns:

functor which composes successful results to completable future with another result

composeStatus

static <T> Function<Result<T>,CompletableFuture<Status>> composeStatus(Function<T,CompletableFuture<Status>> mapper)

Create functor to compose the successful result to next completable future with status. Failed results will be composed to its statuses.

This helper is designed to be used as CompletableFuture.thenCompose(java.util.function.Function) argument

Example of usage:

 
 // Execute one query, with opening new transaction
 session.executeDataQuery(...)
    // Execute second query if first was successful
    .thenCompose(Result.compose(fisrt -> session.executeDataQuery(...)))
    // Commit transaction after two successful query executions
    .thenCompose(Result.composeStatus(second -> session.commitTransaction(...)));
 

Type Parameters:

T - type of value in Result

Parameters:

mapper - mapper from successful value to completable future with status

Returns:

functor which composes successful results to completable future with status

composeValue

static <T,U> Function<Result<T>,CompletableFuture<Result<U>>> composeValue(U value)

Create functor to compose the successful result to completed future with specified value. Failed results will be passed as is.

This helper is designed to be used as CompletableFuture.thenCompose(java.util.function.Function) argument

Example of usage:

 
 // Execute one query
 session.executeDataQuery(...)
    // Execute second query if first was successful
    .thenCompose(Result.compose(fisrt -> session
        .executeDataQuery(...)
        // But use first request result as the result of
        .thenCompose(Result.composeValue(first))
    )
 )
 

Type Parameters:

T - type of value in Result

U - type of composed value

Parameters:

value - value to create completed future

Returns:

functor which composes successful results to completed future with specified value