Add AuthorSpecifications: PredicateSpecification/DeleteSpecification/UpdateSpecification helpers

src/main/java/com/ankurm/sdjpa4demo/repo/AuthorSpecifications.java

@@ -0,0 +1,36 @@
+package com.ankurm.sdjpa4demo.repo;
+
+import com.ankurm.sdjpa4demo.domain.Author;
+import org.springframework.data.jpa.domain.DeleteSpecification;
+import org.springframework.data.jpa.domain.PredicateSpecification;
+import org.springframework.data.jpa.domain.UpdateSpecification;
+
+/**
+ * Reusable Specification-family helpers for Author, exercising the refined Specification API
+ * introduced in Spring Data JPA 4.0: {@link PredicateSpecification} (context-agnostic, reusable
+ * across select/update/delete), {@link DeleteSpecification} (CriteriaDelete-backed bulk delete),
+ * and {@link UpdateSpecification} (CriteriaUpdate-backed bulk update).
+ */
+public final class AuthorSpecifications {
+
+    private AuthorSpecifications() { }
+
+    // PredicateSpecification: a bare Predicate, usable regardless of whether the surrounding
+    // query is a select, update, or delete - this exact instance is reused for both below.
+    public static PredicateSpecification<Author> hasCountry(String country) {
+        return (root, cb) -> cb.equal(root.get("country"), country);
+    }
+
+    // DeleteSpecification: explicit CriteriaDelete-typed specification for a bulk delete.
+    public static DeleteSpecification<Author> byCountryDelete(String country) {
+        return (root, delete, cb) -> cb.equal(root.get("country"), country);
+    }
+
+    // UpdateSpecification: composes an UpdateOperation (the SET clause, over CriteriaUpdate)
+    // with a PredicateSpecification (the WHERE clause) via UpdateSpecification.update(...).where(...).
+    public static UpdateSpecification<Author> relabelCountry(String from, String to) {
+        return UpdateSpecification
+                .<Author>update((root, update, cb) -> update.set(root.get("country"), to))
+                .where(hasCountry(from));
+    }
+}