Add expression support for `@MappedCollection` annotation.

See #1325
Original pull request: #1461

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/BasicRelationalPersistentProperty.java

@@ -27,7 +27,6 @@ import org.springframework.data.relational.core.mapping.Embedded.OnEmpty;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
 import org.springframework.data.spel.EvaluationContextProvider;
 import org.springframework.data.util.Lazy;
-import org.springframework.data.util.Optionals;
 import org.springframework.expression.Expression;
 import org.springframework.expression.ParserContext;
 import org.springframework.expression.common.LiteralExpression;
@@ -53,12 +52,14 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 	private final Lazy<SqlIdentifier> columnName;
 	private final @Nullable Expression columnNameExpression;
 	private final Lazy<Optional<SqlIdentifier>> collectionIdColumnName;
+	private final @Nullable Expression collectionIdColumnNameExpression;
 	private final Lazy<SqlIdentifier> collectionKeyColumnName;
+	private final @Nullable Expression collectionKeyColumnNameExpression;
 	private final boolean isEmbedded;
 	private final String embeddedPrefix;
 	private final NamingStrategy namingStrategy;
 	private boolean forceQuote = true;
-	private ExpressionEvaluator spelExpressionProcessor = new ExpressionEvaluator(EvaluationContextProvider.DEFAULT);
+	private ExpressionEvaluator expressionEvaluator = new ExpressionEvaluator(EvaluationContextProvider.DEFAULT);
 
 	/**
 	 * Creates a new {@link BasicRelationalPersistentProperty}.
@@ -99,38 +100,58 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 				.map(Embedded::prefix) //
 				.orElse("");
 
+		Lazy<Optional<SqlIdentifier>> collectionIdColumnName = null;
+		Lazy<SqlIdentifier> collectionKeyColumnName = Lazy
+				.of(() -> createDerivedSqlIdentifier(namingStrategy.getKeyColumn(this)));
+
+		if (isAnnotationPresent(MappedCollection.class)) {
+
+			MappedCollection mappedCollection = getRequiredAnnotation(MappedCollection.class);
+
+			if (StringUtils.hasText(mappedCollection.idColumn())) {
+				collectionIdColumnName = Lazy.of(() -> Optional.of(createSqlIdentifier(mappedCollection.idColumn())));
+			}
+
+			this.collectionIdColumnNameExpression = detectExpression(mappedCollection.idColumn());
+
+			collectionKeyColumnName = Lazy.of(
+					() -> StringUtils.hasText(mappedCollection.keyColumn()) ? createSqlIdentifier(mappedCollection.keyColumn())
+							: createDerivedSqlIdentifier(namingStrategy.getKeyColumn(this)));
+
+			this.collectionKeyColumnNameExpression = detectExpression(mappedCollection.keyColumn());
+		} else {
+
+			this.collectionIdColumnNameExpression = null;
+			this.collectionKeyColumnNameExpression = null;
+		}
+
 		if (isAnnotationPresent(Column.class)) {
 
 			Column column = getRequiredAnnotation(Column.class);
 
-			columnName = Lazy.of(() -> StringUtils.hasText(column.value()) ? createSqlIdentifier(column.value())
+			this.columnName = Lazy.of(() -> StringUtils.hasText(column.value()) ? createSqlIdentifier(column.value())
 					: createDerivedSqlIdentifier(namingStrategy.getColumnName(this)));
-			columnNameExpression = detectExpression(column.value());
+			this.columnNameExpression = detectExpression(column.value());
+
+			if (collectionIdColumnName == null && StringUtils.hasText(column.value())) {
+				collectionIdColumnName = Lazy.of(() -> Optional.of(createSqlIdentifier(column.value())));
+			}
 
 		} else {
-			columnName = Lazy.of(() -> createDerivedSqlIdentifier(namingStrategy.getColumnName(this)));
+			this.columnName = Lazy.of(() -> createDerivedSqlIdentifier(namingStrategy.getColumnName(this)));
-			columnNameExpression = null;
+			this.columnNameExpression = null;
 		}
 
-		// TODO: support expressions for MappedCollection
+		if (collectionIdColumnName == null) {
-		this.collectionIdColumnName = Lazy.of(() -> Optionals
+			collectionIdColumnName = Lazy.of(Optional.empty());
-				.toStream(Optional.ofNullable(findAnnotation(MappedCollection.class)) //
+		}
-						.map(MappedCollection::idColumn), //
+
-						Optional.ofNullable(findAnnotation(Column.class)) //
+		this.collectionIdColumnName = collectionIdColumnName;
-								.map(Column::value)) //
+		this.collectionKeyColumnName = collectionKeyColumnName;
-				.filter(StringUtils::hasText) //
-				.findFirst() //
-				.map(this::createSqlIdentifier)); //
-
-		this.collectionKeyColumnName = Lazy.of(() -> Optionals //
-				.toStream(Optional.ofNullable(findAnnotation(MappedCollection.class)).map(MappedCollection::keyColumn)) //
-				.filter(StringUtils::hasText).findFirst() //
-				.map(this::createSqlIdentifier) //
-				.orElseGet(() -> createDerivedSqlIdentifier(namingStrategy.getKeyColumn(this))));
 	}
 
-	void setSpelExpressionProcessor(ExpressionEvaluator spelExpressionProcessor) {
+	void setExpressionEvaluator(ExpressionEvaluator expressionEvaluator) {
-		this.spelExpressionProcessor = spelExpressionProcessor;
+		this.expressionEvaluator = expressionEvaluator;
 	}
 
 	/**
@@ -184,7 +205,7 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 			return columnName.get();
 		}
 
-		return createSqlIdentifier(spelExpressionProcessor.evaluate(columnNameExpression));
+		return createSqlIdentifier(expressionEvaluator.evaluate(columnNameExpression));
 	}
 
 	@Override
@@ -195,13 +216,27 @@ public class BasicRelationalPersistentProperty extends AnnotationBasedPersistent
 	@Override
 	public SqlIdentifier getReverseColumnName(PersistentPropertyPathExtension path) {
 
-		return collectionIdColumnName.get()
+		if (collectionIdColumnNameExpression == null) {
-				.orElseGet(() -> createDerivedSqlIdentifier(this.namingStrategy.getReverseColumnName(path)));
+
+			return collectionIdColumnName.get()
+					.orElseGet(() -> createDerivedSqlIdentifier(this.namingStrategy.getReverseColumnName(path)));
+		}
+
+		return createSqlIdentifier(expressionEvaluator.evaluate(collectionIdColumnNameExpression));
 	}
 
 	@Override
 	public SqlIdentifier getKeyColumn() {
-		return isQualified() ? collectionKeyColumnName.get() : null;
+
+		if (!isQualified()) {
+			return null;
+		}
+
+		if (collectionKeyColumnNameExpression == null) {
+			return collectionKeyColumnName.get();
+		}
+
+		return createSqlIdentifier(expressionEvaluator.evaluate(collectionKeyColumnNameExpression));
 	}
 
 	@Override

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/ExpressionEvaluator.java

@@ -14,7 +14,7 @@ import org.springframework.util.Assert;
  *
  * @author Kurt Niemi
  * @see SqlIdentifierSanitizer
- * @since 3.1
+ * @since 3.2
  */
 class ExpressionEvaluator {
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/MappedCollection.java

@@ -37,8 +37,9 @@ import java.util.Set;
 public @interface MappedCollection {
 
 	/**
-	 * The column name for id column in the corresponding relationship table. Defaults to {@link NamingStrategy} usage if
+	 * The column name for id column in the corresponding relationship table. The attribute supports SpEL expressions to
-	 * the value is empty.
+	 * dynamically calculate the column name on a per-operation basis. Defaults to {@link NamingStrategy} usage if the
+	 * value is empty.
 	 *
 	 * @see NamingStrategy#getReverseColumnName(RelationalPersistentProperty)
 	 */
@@ -46,7 +47,8 @@ public @interface MappedCollection {
 
 	/**
 	 * The column name for key columns of {@link List} or {@link Map} collections in the corresponding relationship table.
-	 * Defaults to {@link NamingStrategy} usage if the value is empty.
+	 * The attribute supports SpEL expressions to dynamically calculate the column name on a per-operation basis. Defaults
+	 * to {@link NamingStrategy} usage if the value is empty.
 	 *
 	 * @see NamingStrategy#getKeyColumn(RelationalPersistentProperty)
 	 */

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/RelationalMappingContext.java

@@ -83,6 +83,13 @@ public class RelationalMappingContext
 		this.forceQuote = forceQuote;
 	}
 
+	/**
+	 * Set the {@link SqlIdentifierSanitizer} to sanitize
+	 * {@link org.springframework.data.relational.core.sql.SqlIdentifier identifiers} created from SpEL expressions.
+	 *
+	 * @param sanitizer must not be {@literal null}.
+	 * @since 3.2
+	 */
 	public void setSqlIdentifierSanitizer(SqlIdentifierSanitizer sanitizer) {
 		this.expressionEvaluator.setSanitizer(sanitizer);
 	}
@@ -119,7 +126,7 @@ public class RelationalMappingContext
 
 	protected void applyDefaults(BasicRelationalPersistentProperty persistentProperty) {
 		persistentProperty.setForceQuote(isForceQuote());
-		persistentProperty.setSpelExpressionProcessor(this.expressionEvaluator);
+		persistentProperty.setExpressionEvaluator(this.expressionEvaluator);
 	}
 
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/SqlIdentifierSanitizer.java

@@ -9,7 +9,7 @@ import org.springframework.util.Assert;
  *
  * @author Kurt Niemi
  * @author Mark Paluch
- * @since 3.1
+ * @since 3.2
  * @see RelationalMappingContext#setSqlIdentifierSanitizer(SqlIdentifierSanitizer)
  */
 @FunctionalInterface

spring-data-relational/src/test/java/org/springframework/data/relational/core/mapping/BasicRelationalPersistentPropertyUnitTests.java

@@ -72,14 +72,24 @@ public class BasicRelationalPersistentPropertyUnitTests {
 	@Test // GH-1325
 	void testRelationalPersistentEntitySpelExpressions() {
 
-		assertThat(entity.getRequiredPersistentProperty("spelExpression1").getColumnName()).isEqualTo(quoted("THE_FORCE_IS_WITH_YOU"));
+		assertThat(entity.getRequiredPersistentProperty("spelExpression1").getColumnName())
+				.isEqualTo(quoted("THE_FORCE_IS_WITH_YOU"));
 		assertThat(entity.getRequiredPersistentProperty("littleBobbyTables").getColumnName())
 				.isEqualTo(quoted("DROPALLTABLES"));
 
 		// Test that sanitizer does affect non-spel expressions
-		assertThat(entity.getRequiredPersistentProperty(
+		assertThat(entity.getRequiredPersistentProperty("poorDeveloperProgrammaticallyAskingToShootThemselvesInTheFoot")
-				"poorDeveloperProgrammaticallyAskingToShootThemselvesInTheFoot").getColumnName())
+				.getColumnName()).isEqualTo(quoted("--; DROP ALL TABLES;--"));
-				.isEqualTo(quoted("--; DROP ALL TABLES;--"));
+	}
+
+	@Test // GH-1325
+	void shouldEvaluateMappedCollectionExpressions() {
+
+		RelationalPersistentEntity<?> entity = context.getRequiredPersistentEntity(WithMappedCollection.class);
+		RelationalPersistentProperty property = entity.getRequiredPersistentProperty("someList");
+
+		assertThat(property.getKeyColumn()).isEqualTo(quoted("key_col"));
+		assertThat(property.getReverseColumnName(null)).isEqualTo(quoted("id_col"));
 	}
 
 	@Test // DATAJDBC-111
@@ -166,18 +176,16 @@ public class BasicRelationalPersistentPropertyUnitTests {
 		public static String spelExpression1Value = "THE_FORCE_IS_WITH_YOU";
 
 		public static String littleBobbyTablesValue = "--; DROP ALL TABLES;--";
-		@Column(value="#{T(org.springframework.data.relational.core.mapping." +
+		@Column(value = "#{T(org.springframework.data.relational.core.mapping."
-				"BasicRelationalPersistentPropertyUnitTests$DummyEntity" +
+				+ "BasicRelationalPersistentPropertyUnitTests$DummyEntity"
-				").spelExpression1Value}")
+				+ ").spelExpression1Value}") private String spelExpression1;
-		private String spelExpression1;
 
-		@Column(value="#{T(org.springframework.data.relational.core.mapping." +
+		@Column(value = "#{T(org.springframework.data.relational.core.mapping."
-				"BasicRelationalPersistentPropertyUnitTests$DummyEntity" +
+				+ "BasicRelationalPersistentPropertyUnitTests$DummyEntity"
-				").littleBobbyTablesValue}")
+				+ ").littleBobbyTablesValue}") private String littleBobbyTables;
-		private String littleBobbyTables;
 
-		@Column(value="--; DROP ALL TABLES;--")
+		@Column(
-		private String poorDeveloperProgrammaticallyAskingToShootThemselvesInTheFoot;
+				value = "--; DROP ALL TABLES;--") private String poorDeveloperProgrammaticallyAskingToShootThemselvesInTheFoot;
 
 		// DATAJDBC-111
 		private @Embedded(onEmpty = OnEmpty.USE_NULL) EmbeddableEntity embeddableEntity;
@@ -199,6 +207,11 @@ public class BasicRelationalPersistentPropertyUnitTests {
 		}
 	}
 
+	static class WithMappedCollection {
+
+		@MappedCollection(idColumn = "#{'id_col'}", keyColumn = "#{'key_col'}") private List<Integer> someList;
+	}
+
 	@SuppressWarnings("unused")
 	private enum SomeEnum {
 		ALPHA