Add support for Value Expressions.

We now support Value Expressions such as `#{1+1}-${spring.application.name:fallback-value}` that are composed of SpEL expressions, literals and Property Placeholders.

See #2369
Original pull request: #3036

Author: christophstrobl

src/main/java/org/springframework/data/mapping/context/AbstractMappingContext.java

@@ -40,15 +40,19 @@
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
+import org.springframework.context.EnvironmentAware;
 import org.springframework.core.KotlinDetector;
 import org.springframework.core.NativeDetector;
+import org.springframework.core.env.Environment;
+import org.springframework.core.env.StandardEnvironment;
 import org.springframework.data.domain.ManagedTypes;
 import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.PersistentPropertyPath;
 import org.springframework.data.mapping.PersistentPropertyPaths;
 import org.springframework.data.mapping.PropertyPath;
+import org.springframework.data.mapping.model.AbstractPersistentProperty;
 import org.springframework.data.mapping.model.BeanWrapperPropertyAccessorFactory;
 import org.springframework.data.mapping.model.ClassGeneratingPropertyAccessorFactory;
 import org.springframework.data.mapping.model.EntityInstantiators;
@@ -59,6 +63,7 @@
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.spel.EvaluationContextProvider;
 import org.springframework.data.spel.ExtensionAwareEvaluationContextProvider;
+import org.springframework.data.support.EnvironmentAccessor;
 import org.springframework.data.util.KotlinReflectionUtils;
 import org.springframework.data.util.NullableWrapperConverters;
 import org.springframework.data.util.Optionals;
@@ -89,7 +94,7 @@
  * @author Christoph Strobl
  */
 public abstract class AbstractMappingContext<E extends MutablePersistentEntity<?, P>, P extends PersistentProperty<P>>
-		implements MappingContext<E, P>, ApplicationEventPublisherAware, ApplicationContextAware, InitializingBean {
+		implements MappingContext<E, P>, ApplicationEventPublisherAware, ApplicationContextAware, InitializingBean, EnvironmentAware {
 
 	private static final Log LOGGER = LogFactory.getLog(MappingContext.class);
 
@@ -100,6 +105,7 @@ public abstract class AbstractMappingContext<E extends MutablePersistentEntity<?
 
 	private @Nullable ApplicationEventPublisher applicationEventPublisher;
 	private EvaluationContextProvider evaluationContextProvider = EvaluationContextProvider.DEFAULT;
+	private @Nullable EnvironmentAccessor environmentAccessor;
 
 	private ManagedTypes managedTypes = ManagedTypes.empty();
 
@@ -138,6 +144,10 @@ public void setApplicationContext(ApplicationContext applicationContext) throws
 		}
 	}
 
+	public void setEnvironment(Environment environment) {
+		this.environmentAccessor = new DelegatingEnvironmentAccessor(environment);
+	}
+
 	/**
 	 * Sets the {@link Set} of types to populate the context initially.
 	 *
@@ -406,6 +416,7 @@ private E doAddPersistentEntity(TypeInformation<?> typeInformation) {
 
 			E entity = createPersistentEntity(userTypeInformation);
 			entity.setEvaluationContextProvider(evaluationContextProvider);
+			entity.setEnvironmentAccessor(environmentAccessor);
 
 			// Eagerly cache the entity as we might have to find it during recursive lookups.
 			persistentEntities.put(userTypeInformation, Optional.of(entity));
@@ -477,6 +488,10 @@ public Collection<TypeInformation<?>> getManagedTypes() {
 
 	@Override
 	public void afterPropertiesSet() {
+
+		if(this.environmentAccessor == null) {
+			this.environmentAccessor = new DelegatingEnvironmentAccessor(new StandardEnvironment());
+		}
 		initialize();
 	}
 
@@ -579,6 +594,9 @@ private void createAndRegisterProperty(Property input) {
 				return;
 			}
 
+			if(property instanceof AbstractPersistentProperty<?> pp) {
+				pp.setEnvironmentAccessor(environmentAccessor);
+			}
 			entity.addPersistentProperty(property);
 
 			if (property.isAssociation()) {
@@ -776,4 +794,32 @@ public boolean matches(String name, Class<?> type) {
 			}
 		}
 	}
+
+	/**
+	 * @author Christoph Strobl
+	 * @since 3.3
+	 */
+	public static class DelegatingEnvironmentAccessor implements EnvironmentAccessor {
+
+		private final Environment environment;
+
+		static EnvironmentAccessor standard() {
+			return new DelegatingEnvironmentAccessor(new StandardEnvironment());
+		}
+
+		public DelegatingEnvironmentAccessor(Environment environment) {
+			this.environment = environment;
+		}
+
+		@Nullable
+		@Override
+		public String getProperty(String key) {
+			return environment.getProperty(key);
+		}
+
+		@Override
+		public String resolvePlaceholders(String text) {
+			return environment.resolvePlaceholders(text);
+		}
+	}
 }

src/main/java/org/springframework/data/mapping/model/AbstractPersistentProperty.java

@@ -27,6 +27,7 @@
 import org.springframework.data.mapping.Association;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.support.EnvironmentAccessor;
 import org.springframework.data.util.KotlinReflectionUtils;
 import org.springframework.data.util.Lazy;
 import org.springframework.data.util.ReflectionUtils;
@@ -74,6 +75,9 @@ public abstract class AbstractPersistentProperty<P extends PersistentProperty<P>
 	private final Lazy<Boolean> readable;
 	private final boolean immutable;
 
+
+	private @Nullable EnvironmentAccessor environmentAccessor;
+
 	public AbstractPersistentProperty(Property property, PersistentEntity<?, P> owner,
 			SimpleTypeHolder simpleTypeHolder) {
 
@@ -306,6 +310,14 @@ protected TypeInformation<?> getActualTypeInformation() {
 		return targetType == null ? information.getRequiredActualType() : targetType;
 	}
 
+	protected EnvironmentAccessor getEnvironmentAccessor() {
+		return environmentAccessor;
+	}
+
+	public void setEnvironmentAccessor(EnvironmentAccessor environmentAccessor) {
+		this.environmentAccessor = environmentAccessor;
+	}
+
 	@Override
 	public boolean equals(@Nullable Object obj) {
 

src/main/java/org/springframework/data/mapping/model/AnnotationBasedPersistentProperty.java

@@ -37,6 +37,7 @@
 import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.support.EnvironmentAccessor;
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.Lazy;
 import org.springframework.data.util.Optionals;

src/main/java/org/springframework/data/mapping/model/BasicPersistentEntity.java

@@ -36,6 +36,7 @@
 import org.springframework.data.mapping.*;
 import org.springframework.data.spel.EvaluationContextProvider;
 import org.springframework.data.spel.ExpressionDependencies;
+import org.springframework.data.support.EnvironmentAccessor;
 import org.springframework.data.support.IsNewStrategy;
 import org.springframework.data.support.PersistableIsNewStrategy;
 import org.springframework.data.util.Lazy;
@@ -79,6 +80,7 @@ public class BasicPersistentEntity<T, P extends PersistentProperty<P>> implement
 	private @Nullable P versionProperty;
 	private PersistentPropertyAccessorFactory propertyAccessorFactory;
 	private EvaluationContextProvider evaluationContextProvider = EvaluationContextProvider.DEFAULT;
+	private @Nullable EnvironmentAccessor environmentAccessor;
 
 	private final Lazy<Alias> typeAlias;
 	private final Lazy<IsNewStrategy> isNewStrategy;
@@ -205,10 +207,8 @@ public void addPersistentProperty(P property) {
 			if (versionProperty != null) {
 
 				throw new MappingException(
-						String.format(
-								"Attempt to add version property %s but already have property %s registered "
-										+ "as version; Check your mapping configuration",
-								property.getField(), versionProperty.getField()));
+						String.format("Attempt to add version property %s but already have property %s registered "
+								+ "as version; Check your mapping configuration", property.getField(), versionProperty.getField()));
 			}
 
 			this.versionProperty = property;
@@ -220,6 +220,11 @@ public void setEvaluationContextProvider(EvaluationContextProvider provider) {
 		this.evaluationContextProvider = provider;
 	}
 
+	@Override
+	public void setEnvironmentAccessor(EnvironmentAccessor accessor) {
+		this.environmentAccessor = accessor;
+	}
+
 	/**
 	 * Returns the given property if it is a better candidate for the id property than the current id property.
 	 *
@@ -443,6 +448,17 @@ protected EvaluationContext getEvaluationContext(Object rootObject, ExpressionDe
 		return evaluationContextProvider.getEvaluationContext(rootObject, dependencies);
 	}
 
+	/**
+	 * Obtain the {@link EnvironmentAccessor} providing access to the current
+	 * {@link org.springframework.core.env.Environment}.
+	 *
+	 * @return never {@literal null}.
+	 * @since 3.3
+	 */
+	protected EnvironmentAccessor getEnvironmentAccessor() {
+		return environmentAccessor;
+	}
+
 	/**
 	 * Returns the default {@link IsNewStrategy} to be used. Will be a {@link PersistentEntityIsNewStrategy} by default.
 	 * Note, that this strategy only gets used if the entity doesn't implement {@link Persistable} as this indicates the

src/main/java/org/springframework/data/mapping/model/MutablePersistentEntity.java

@@ -21,6 +21,7 @@
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.spel.EvaluationContextProvider;
+import org.springframework.data.support.EnvironmentAccessor;
 
 /**
  * Interface capturing mutator methods for {@link PersistentEntity}s.
@@ -66,4 +67,12 @@ public interface MutablePersistentEntity<T, P extends PersistentProperty<P>> ext
 	 * @param provider must not be {@literal null}.
 	 */
 	void setEvaluationContextProvider(EvaluationContextProvider provider);
+
+	/**
+	 * Sets the {@link EnvironmentAccessor} to be used by the entity.
+	 *
+	 * @param accessor must not be {@literal null}.
+	 * @since 3.3
+	 */
+	void setEnvironmentAccessor(EnvironmentAccessor accessor);
 }

src/main/java/org/springframework/data/support/EnvironmentAccessor.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.data.support;
+
+import org.springframework.lang.Nullable;
+
+/**
+ * @author Christoph Strobl
+ * @since 3.3
+ */
+public interface EnvironmentAccessor extends PlaceholderResolver {
+
+	@Nullable
+	String getProperty(String key);
+
+}

src/main/java/org/springframework/data/support/PlaceholderResolver.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.support;
+
+/**
+ * @author Christoph Strobl
+ * @since 3.3
+ */
+public interface PlaceholderResolver {
+
+	String resolvePlaceholders(String text);
+}