working on #29 Implement FluentQuery introduced in spring data 2.6 to support projection

Author: mhewedy

pom.xml

@@ -6,7 +6,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.4.2</version>
+        <version>2.6.1</version> <!-- this version is not inherited by projects using the library, as all spring dependencies are optional -->
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
 

src/test/java/com/github/mhewedy/expressions/ExpressionsRepositoryImplTest.java

@@ -2,7 +2,9 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.github.mhewedy.expressions.model.*;
+import lombok.AllArgsConstructor;
 import lombok.SneakyThrows;
+import lombok.ToString;
 import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -14,6 +16,7 @@
 import org.springframework.boot.jdbc.EmbeddedDatabaseConnection;
 import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
 import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.data.domain.Example;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Sort;
@@ -29,6 +32,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.UUID;
+import java.util.stream.Collectors;
 
 import static com.github.mhewedy.expressions.model.Status.ACTIVE;
 import static com.github.mhewedy.expressions.model.Status.NOT_ACTIVE;
@@ -588,6 +592,44 @@ public void testHijrahDate_InJava() {
         // where e.h_birth_date>=?
     }
 
+    @Test
+    public void testFluentQueryInQBE() {
+        @ToString
+        @AllArgsConstructor
+        class EmployeeProjectionDTO {
+            public final String firstName;
+            public final String lastName;
+        }
+
+        List<EmployeeProjectionDTO> list = employeeRepository.findBy(Example.of(new Employee()),
+                query -> query.project("firstName", "lastName")
+                        .stream()
+                        .map(it -> new EmployeeProjectionDTO(it.firstName, it.lastName))
+                        .collect(Collectors.toList())
+        );
+        System.out.println(list);
+
+        // sql:
+        /*
+        SELECT employee0_.id               AS id1_2_,
+               employee0_.created_date     AS created_2_2_,
+               employee0_.active           AS active3_2_,
+               employee0_.age              AS age4_2_,
+               employee0_.birth_date       AS birth_da5_2_,
+               employee0_.department_id    AS departm14_2_,
+               employee0_.first_name       AS first_na6_2_,
+               employee0_.h_birth_date     AS h_birth_7_2_,
+               employee0_.hire_date        AS hire_dat8_2_,
+               employee0_.last_name        AS last_nam9_2_,
+               employee0_.employee_name_ar AS employe10_2_,
+               employee0_.employee_name_en AS employe11_2_,
+               employee0_.serial           AS serial12_2_,
+               employee0_.type             AS type13_2_
+        FROM   employee employee0_
+        WHERE ?= 1
+         */
+    }
+
     @SneakyThrows
     private String loadResourceJsonFile(String name) {
         File file = ResourceUtils.getFile("classpath:" + name + ".json");