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DataAccessUtils result accessors with Optional return value (#27735)
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@KaidosGH
KaidosGH committed Jul 14, 2023
1 parent 793581e commit 4b80b0f
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87 changes: 87 additions & 0 deletions spring-tx/src/main/java/org/springframework/dao/support/DataAccessUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,10 @@
package org.springframework.dao.support;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.stream.Stream;

import org.springframework.dao.DataAccessException;
import org.springframework.dao.EmptyResultDataAccessException;
Expand Down Expand Up @@ -56,6 +60,89 @@ public static <T> T singleResult(@Nullable Collection<T> results) throws Incorre
return results.iterator().next();
}

/**
* Return a single result object from the given Stream.
* <p>Returns {@code null} if 0 result objects found;
* throws an exception if more than 1 element found.
* @param results the result Stream (can be {@code null})
* @return the single result object, or {@code null} if none
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Stream
*/
@Nullable
public static <T> T singleResult(@Nullable Stream<T> results) throws IncorrectResultSizeDataAccessException {
if (results == null) {
return null;
}
try (results) {
List<T> resultList = results.limit(2).toList();
if (resultList.size() > 1) {
throw new IncorrectResultSizeDataAccessException(1);
}
return CollectionUtils.isEmpty(resultList) ? null : resultList.get(0);
}
}

/**
* Return a single result object from the given Iterator.
* <p>Returns {@code null} if 0 result objects found;
* throws an exception if more than 1 element found.
* @param results the result Iterator (can be {@code null})
* @return the single result object, or {@code null} if none
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Iterator
*/
@Nullable
public static <T> T singleResult(@Nullable Iterator<T> results) throws IncorrectResultSizeDataAccessException {
if (results == null) {
return null;
}
T result = results.hasNext() ? results.next() : null;
if (results.hasNext()) {
throw new IncorrectResultSizeDataAccessException(1);
}
return result;
}

/**
* Return a single result object from the given Collection.
* <p>Returns {@code Optional.empty()} if 0 result objects found;
* throws an exception if more than 1 element found.
* @param results the result Collection (can be {@code null})
* @return the single optional result object, or {@code Optional.empty()} if none
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Collection
*/
public static <T> Optional<T> optionalResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
return Optional.ofNullable(singleResult(results));
}

/**
* Return a single result object from the given Stream.
* <p>Returns {@code Optional.empty()} if 0 result objects found;
* throws an exception if more than 1 element found.
* @param results the result Stream (can be {@code null})
* @return the single optional result object, or {@code Optional.empty()} if none
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Stream
*/
public static <T> Optional<T> optionalResult(@Nullable Stream<T> results) throws IncorrectResultSizeDataAccessException {
return Optional.ofNullable(singleResult(results));
}

/**
* Return a single result object from the given Iterator.
* <p>Returns {@code Optional.empty()} if 0 result objects found;
* throws an exception if more than 1 element found.
* @param results the result Iterator (can be {@code null})
* @return the single optional result object, or {@code Optional.empty()} if none
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Iterator
*/
public static <T> Optional<T> optionalResult(@Nullable Iterator<T> results) throws IncorrectResultSizeDataAccessException {
return Optional.ofNullable(singleResult(results));
}

/**
* Return a single result object from the given Collection.
* <p>Throws an exception if 0 or more than 1 element found.
Expand Down
63 changes: 63 additions & 0 deletions spring-tx/src/test/java/org/springframework/dao/support/DataAccessUtilsTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Optional;
import java.util.function.Consumer;

import org.junit.jupiter.api.Test;
Expand All @@ -47,6 +48,13 @@ public void withEmptyCollection() {

assertThat(DataAccessUtils.uniqueResult(col)).isNull();

assertThat(DataAccessUtils.singleResult(col)).isNull();
assertThat(DataAccessUtils.singleResult(col.stream())).isNull();
assertThat(DataAccessUtils.singleResult(col.iterator())).isNull();
assertThat(DataAccessUtils.optionalResult(col)).isEmpty();
assertThat(DataAccessUtils.optionalResult(col.stream())).isEmpty();
assertThat(DataAccessUtils.optionalResult(col.iterator())).isEmpty();

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.requiredUniqueResult(col))
.satisfies(sizeRequirements(1, 0));
Expand Down Expand Up @@ -89,6 +97,30 @@ public void withTooLargeCollection() {
assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.longResult(col))
.satisfies(sizeRequirements(1, 2));

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.singleResult(col))
.satisfies(sizeRequirements(1, 2));

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.singleResult(col.stream()))
.satisfies(sizeRequirements(1));

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.singleResult(col.iterator()))
.satisfies(sizeRequirements(1));

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.optionalResult(col))
.satisfies(sizeRequirements(1, 2));

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.optionalResult(col.stream()))
.satisfies(sizeRequirements(1));

assertThatExceptionOfType(IncorrectResultSizeDataAccessException.class).isThrownBy(() ->
DataAccessUtils.optionalResult(col.iterator()))
.satisfies(sizeRequirements(1));
}

@Test
Expand All @@ -102,6 +134,12 @@ public void withInteger() {
assertThat(DataAccessUtils.objectResult(col, String.class)).isEqualTo("5");
assertThat(DataAccessUtils.intResult(col)).isEqualTo(5);
assertThat(DataAccessUtils.longResult(col)).isEqualTo(5);
assertThat(DataAccessUtils.singleResult(col)).isEqualTo(5);
assertThat(DataAccessUtils.singleResult(col.stream())).isEqualTo(5);
assertThat(DataAccessUtils.singleResult(col.iterator())).isEqualTo(5);
assertThat(DataAccessUtils.optionalResult(col)).isEqualTo(Optional.of(5));
assertThat(DataAccessUtils.optionalResult(col.stream())).isEqualTo(Optional.of(5));
assertThat(DataAccessUtils.optionalResult(col.iterator())).isEqualTo(Optional.of(5));
}

@Test
Expand Down Expand Up @@ -139,6 +177,12 @@ public void withLong() {
assertThat(DataAccessUtils.objectResult(col, String.class)).isEqualTo("5");
assertThat(DataAccessUtils.intResult(col)).isEqualTo(5);
assertThat(DataAccessUtils.longResult(col)).isEqualTo(5);
assertThat(DataAccessUtils.singleResult(col)).isEqualTo(Long.valueOf(5L));
assertThat(DataAccessUtils.singleResult(col.stream())).isEqualTo(Long.valueOf(5L));
assertThat(DataAccessUtils.singleResult(col.iterator())).isEqualTo(Long.valueOf(5L));
assertThat(DataAccessUtils.optionalResult(col)).isEqualTo(Optional.of(5L));
assertThat(DataAccessUtils.optionalResult(col.stream())).isEqualTo(Optional.of(5L));
assertThat(DataAccessUtils.optionalResult(col.iterator())).isEqualTo(Optional.of(5L));
}

@Test
Expand All @@ -149,6 +193,12 @@ public void withString() {
assertThat(DataAccessUtils.uniqueResult(col)).isEqualTo("test1");
assertThat(DataAccessUtils.requiredUniqueResult(col)).isEqualTo("test1");
assertThat(DataAccessUtils.objectResult(col, String.class)).isEqualTo("test1");
assertThat(DataAccessUtils.singleResult(col)).isEqualTo("test1");
assertThat(DataAccessUtils.singleResult(col.stream())).isEqualTo("test1");
assertThat(DataAccessUtils.singleResult(col.iterator())).isEqualTo("test1");
assertThat(DataAccessUtils.optionalResult(col)).isEqualTo(Optional.of("test1"));
assertThat(DataAccessUtils.optionalResult(col.stream())).isEqualTo(Optional.of("test1"));
assertThat(DataAccessUtils.optionalResult(col.iterator())).isEqualTo(Optional.of("test1"));

assertThatExceptionOfType(TypeMismatchDataAccessException.class).isThrownBy(() ->
DataAccessUtils.intResult(col));
Expand All @@ -167,6 +217,12 @@ public void withDate() {
assertThat(DataAccessUtils.requiredUniqueResult(col)).isEqualTo(date);
assertThat(DataAccessUtils.objectResult(col, Date.class)).isEqualTo(date);
assertThat(DataAccessUtils.objectResult(col, String.class)).isEqualTo(date.toString());
assertThat(DataAccessUtils.singleResult(col)).isEqualTo(date);
assertThat(DataAccessUtils.singleResult(col.stream())).isEqualTo(date);
assertThat(DataAccessUtils.singleResult(col.iterator())).isEqualTo(date);
assertThat(DataAccessUtils.optionalResult(col)).isEqualTo(Optional.of(date));
assertThat(DataAccessUtils.optionalResult(col.stream())).isEqualTo(Optional.of(date));
assertThat(DataAccessUtils.optionalResult(col.iterator())).isEqualTo(Optional.of(date));

assertThatExceptionOfType(TypeMismatchDataAccessException.class).isThrownBy(() ->
DataAccessUtils.intResult(col));
Expand Down Expand Up @@ -199,6 +255,13 @@ private <E extends IncorrectResultSizeDataAccessException> Consumer<E> sizeRequi
};
}

private <E extends IncorrectResultSizeDataAccessException> Consumer<E> sizeRequirements(
int expectedSize) {
return ex -> {
assertThat(ex.getExpectedSize()).as("expected size").isEqualTo(expectedSize);
};
}

public static class MapPersistenceExceptionTranslator implements PersistenceExceptionTranslator {

// in to out
Expand Down

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