feat: Add interfaces for CRUD services

These were previously in Hilla but are equally useful in Flow applications

flow-server/src/main/java/com/vaadin/flow/Nonnull.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2000-2022 Vaadin Ltd.
+ *
+ * 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
+ *
+ * http://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 com.vaadin.flow;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark either field, method, parameter or type parameter as
+ * non-nullable. It is used by Typescript Generator as a source of type
+ * nullability information.
+ *
+ * This annotation exists because the traditional `jakarta.annotation.Nonnull`
+ * annotation is not applicable to type parameters.
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE_USE })
+public @interface Nonnull {
+}

flow-server/src/main/java/com/vaadin/flow/Nullable.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2000-2022 Vaadin Ltd.
+ *
+ * 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
+ *
+ * http://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 com.vaadin.flow;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark either field, method, parameter or type parameter as
+ * nullable. It is used by Typescript Generator as a source of type nullability
+ * information.
+ *
+ * This annotation exists because the traditional `jakarta.annotation.Nullable`
+ * annotation is not applicable to type parameters.
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE_USE })
+public @interface Nullable {
+}

vaadin-spring/pom.xml

@@ -97,6 +97,26 @@
             <artifactId>spring-data-commons</artifactId>
             <optional>true</optional>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.data</groupId>
+            <artifactId>spring-data-jpa</artifactId>
+            <scope>provided</scope>
+            <exclusions>
+                <exclusion>
+                    <artifactId>aspectjrt</artifactId>
+                    <groupId>org.aspectj</groupId>
+                </exclusion>
+                <exclusion>
+                    <artifactId>jcl-over-slf4j</artifactId>
+                    <groupId>org.slf4j</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.persistence</groupId>
+            <artifactId>jakarta.persistence-api</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>com.vaadin</groupId>
             <artifactId>flow-data</artifactId>

vaadin-spring/src/main/java/com/vaadin/flow/spring/data/CountService.java

@@ -0,0 +1,21 @@
+package com.vaadin.flow.spring.data;
+
+import com.vaadin.flow.Nullable;
+
+import com.vaadin.flow.spring.data.filter.Filter;
+
+/**
+ * A service that can count the given type of objects with a given filter.
+ */
+public interface CountService {
+
+    /**
+     * Counts the number of entities that match the given filter.
+     *
+     * @param filter
+     *            the filter, or {@code null} to use no filter
+     * @return
+     */
+    public long count(@Nullable Filter filter);
+
+}

vaadin-spring/src/main/java/com/vaadin/flow/spring/data/CrudRepositoryService.java

@@ -0,0 +1,70 @@
+package com.vaadin.flow.spring.data;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+import org.springframework.data.repository.CrudRepository;
+
+import com.vaadin.flow.Nullable;
+
+/**
+ * A service that delegates crud operations to a JPA repository.
+ */
+public class CrudRepositoryService<T, ID, R extends CrudRepository<T, ID> & JpaSpecificationExecutor<T>>
+        extends ListRepositoryService<T, ID, R> implements CrudService<T, ID> {
+
+    /*
+     * Creates the service by autodetecting the type of repository and entity to
+     * use from the generics.
+     */
+    public CrudRepositoryService() {
+        super();
+    }
+
+    /**
+     * Creates the service using the given repository.
+     *
+     * @param repository
+     *            the JPA repository
+     */
+    public CrudRepositoryService(R repository) {
+        super(repository);
+    }
+
+    @Override
+    public @Nullable T save(T value) {
+        return getRepository().save(value);
+    }
+
+    /**
+     * Saves the given objects and returns the (potentially) updated objects.
+     * <p>
+     * The returned objects might have new ids or updated consistency versions.
+     *
+     * @param values
+     *            the objects to save
+     * @return the fresh objects
+     */
+    public List<T> saveAll(Iterable<T> values) {
+        List<T> saved = new ArrayList<>();
+        getRepository().saveAll(values).forEach(saved::add);
+        return saved;
+    }
+
+    @Override
+    public void delete(ID id) {
+        getRepository().deleteById(id);
+    }
+
+    /**
+     * Deletes the objects with the given ids.
+     *
+     * @param ids
+     *            the ids of the objects to delete
+     */
+    public void deleteAll(Iterable<ID> ids) {
+        getRepository().deleteAllById(ids);
+    }
+
+}

vaadin-spring/src/main/java/com/vaadin/flow/spring/data/CrudService.java

@@ -0,0 +1,7 @@
+package com.vaadin.flow.spring.data;
+
+/**
+ * A service that can create, read, update, and delete a given type of object.
+ */
+public interface CrudService<T, ID> extends ListService<T>, FormService<T, ID> {
+}

vaadin-spring/src/main/java/com/vaadin/flow/spring/data/FormService.java

@@ -0,0 +1,30 @@
+package com.vaadin.flow.spring.data;
+
+import com.vaadin.flow.Nullable;
+
+/**
+ * A service that can create, update, and delete a given type of object.
+ */
+public interface FormService<T, ID> {
+
+    /**
+     * Saves the given object and returns the (potentially) updated object.
+     * <p>
+     * If you store the object in a SQL database, the returned object might have
+     * a new id or updated consistency version.
+     *
+     * @param value
+     *            the object to save
+     * @return the fresh object or {@code null} if no object was found to update
+     */
+    @Nullable
+    T save(T value);
+
+    /**
+     * Deletes the object with the given id.
+     *
+     * @param id
+     *            the id of the object to delete
+     */
+    void delete(ID id);
+}

vaadin-spring/src/main/java/com/vaadin/flow/spring/data/GetService.java

@@ -0,0 +1,30 @@
+package com.vaadin.flow.spring.data;
+
+import java.util.Optional;
+
+/**
+ * A service that can fetch the given type of object.
+ */
+public interface GetService<T, ID> {
+
+    /**
+     * Gets the object with the given id.
+     *
+     * @param id
+     *            the id of the object
+     * @return the object, or an empty optional if no object with the given id
+     */
+    Optional<T> get(ID id);
+
+    /**
+     * Checks if an object with the given id exists.
+     *
+     * @param id
+     *            the id of the object
+     * @return {@code true} if the object exists, {@code false} otherwise
+     */
+    default boolean exists(ID id) {
+        return get(id).isPresent();
+    }
+
+}

vaadin-spring/src/main/java/com/vaadin/flow/spring/data/JpaFilterConverter.java

@@ -0,0 +1,90 @@
+package com.vaadin.flow.spring.data;
+
+import jakarta.persistence.EntityManager;
+
+import com.vaadin.flow.spring.data.filter.AndFilter;
+import com.vaadin.flow.spring.data.filter.Filter;
+import com.vaadin.flow.spring.data.filter.OrFilter;
+import com.vaadin.flow.spring.data.filter.PropertyStringFilter;
+import jakarta.persistence.criteria.Path;
+import jakarta.persistence.criteria.Root;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.jpa.domain.Specification;
+import org.springframework.stereotype.Component;
+
+/**
+ * Utility class for converting Hilla {@link Filter} specifications into JPA
+ * filter specifications. This class can be used to implement filtering for
+ * custom {@link ListService} or {@link CrudService} implementations that use
+ * JPA as the data source.
+ * <p>
+ * This class requires an EntityManager to be available as a Spring bean and
+ * thus should be injected into the bean that wants to use the converter.
+ * Manually creating new instances of this class will not work.
+ */
+@Component
+public class JpaFilterConverter {
+
+    @Autowired
+    private EntityManager em;
+
+    /**
+     * Converts the given Hilla filter specification into a JPA filter
+     * specification for the specified entity class.
+     * <p>
+     * If the filter contains {@link PropertyStringFilter} instances, their
+     * properties, or nested property paths, need to match the structure of the
+     * entity class. Likewise, their filter values should be in a format that
+     * can be parsed into the type that the property is of.
+     *
+     * @param <T>
+     *            the type of the entity
+     * @param rawFilter
+     *            the filter to convert
+     * @param entity
+     *            the entity class
+     * @return a JPA filter specification for the given filter
+     */
+    public <T> Specification<T> toSpec(Filter rawFilter, Class<T> entity) {
+        if (rawFilter == null) {
+            return Specification.anyOf();
+        }
+        if (rawFilter instanceof AndFilter filter) {
+            return Specification.allOf(filter.getChildren().stream()
+                    .map(f -> toSpec(f, entity)).toList());
+        } else if (rawFilter instanceof OrFilter filter) {
+            return Specification.anyOf(filter.getChildren().stream()
+                    .map(f -> toSpec(f, entity)).toList());
+        } else if (rawFilter instanceof PropertyStringFilter filter) {
+            Class<?> javaType = extractPropertyJavaType(entity,
+                    filter.getPropertyId());
+            return new PropertyStringFilterSpecification<>(filter, javaType);
+        } else {
+            if (rawFilter != null) {
+                throw new IllegalArgumentException("Unknown filter type "
+                        + rawFilter.getClass().getName());
+            }
+            return Specification.anyOf();
+        }
+    }
+
+    private Class<?> extractPropertyJavaType(Class<?> entity,
+            String propertyId) {
+        if (propertyId.contains(".")) {
+            String[] parts = propertyId.split("\\.");
+            Root<?> root = em.getCriteriaBuilder().createQuery(entity)
+                    .from(entity);
+            Path<?> path = root.get(parts[0]);
+            int i = 1;
+            while (i < parts.length) {
+                path = path.get(parts[i]);
+                i++;
+            }
+            return path.getJavaType();
+        } else {
+            return em.getMetamodel().entity(entity).getAttribute(propertyId)
+                    .getJavaType();
+        }
+    }
+
+}