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Document null-safe collection selection/projection support in SpEL

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Closes gh-32208
This commit is contained in:
Sam Brannen
2024-02-11 17:12:45 +01:00
parent 347d085020
commit 4a5dc7c1b0
4 changed files with 317 additions and 0 deletions
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79
spring-expression/src/test/java/org/springframework/expression/spel/SpelDocumentationTests.java
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@@ -648,6 +648,85 @@ class SpelDocumentationTests extends AbstractExpressionTests {
.getValue(context, tesla, String.class);
assertThat(city).isNull();
}
@Test
@SuppressWarnings("unchecked")
void nullSafeSelection() {
IEEE society = new IEEE();
StandardEvaluationContext context = new StandardEvaluationContext(society);
String expression = "members?.?[nationality == 'Serbian']"; // <1>
// evaluates to [Inventor("Nikola Tesla")]
List<Inventor> list = (List<Inventor>) parser.parseExpression(expression)
.getValue(context);
assertThat(list).map(Inventor::getName).containsOnly("Nikola Tesla");
society.members = null;
// evaluates to null - does not throw a NullPointerException
list = (List<Inventor>) parser.parseExpression(expression)
.getValue(context);
assertThat(list).isNull();
}
@Test
@SuppressWarnings("unchecked")
void nullSafeSelectFirst() {
IEEE society = new IEEE();
StandardEvaluationContext context = new StandardEvaluationContext(society);
String expression = "members?.^[nationality == 'Serbian' || nationality == 'Idvor']"; // <1>
// evaluates to Inventor("Nikola Tesla")
Inventor inventor = parser.parseExpression(expression)
.getValue(context, Inventor.class);
assertThat(inventor).extracting(Inventor::getName).isEqualTo("Nikola Tesla");
society.members = null;
// evaluates to null - does not throw a NullPointerException
inventor = parser.parseExpression(expression)
.getValue(context, Inventor.class);
assertThat(inventor).isNull();
}
@Test
@SuppressWarnings("unchecked")
void nullSafeSelectLast() {
IEEE society = new IEEE();
StandardEvaluationContext context = new StandardEvaluationContext(society);
String expression = "members?.$[nationality == 'Serbian' || nationality == 'Idvor']"; // <1>
// evaluates to Inventor("Pupin")
Inventor inventor = parser.parseExpression(expression)
.getValue(context, Inventor.class);
assertThat(inventor).extracting(Inventor::getName).isEqualTo("Pupin");
society.members = null;
// evaluates to null - does not throw a NullPointerException
inventor = parser.parseExpression(expression)
.getValue(context, Inventor.class);
assertThat(inventor).isNull();
}
@Test
@SuppressWarnings("unchecked")
void nullSafeProjection() {
IEEE society = new IEEE();
StandardEvaluationContext context = new StandardEvaluationContext(society);
// evaluates to ["Smiljan", "Idvor"]
List placesOfBirth = parser.parseExpression("members?.![placeOfBirth.city]") // <1>
.getValue(context, List.class);
assertThat(placesOfBirth).containsExactly("Smiljan", "Idvor");
society.members = null;
// evaluates to null - does not throw a NullPointerException
placesOfBirth = parser.parseExpression("members?.![placeOfBirth.city]") // <2>
.getValue(context, List.class);
assertThat(placesOfBirth).isNull();
}
}
@Nested