From 92995b807eb38c61c7a926f078b5ac3a589432fe Mon Sep 17 00:00:00 2001
From: rob bygrave <robin.bygrave@gmail.com>
Date: Sat, 22 Feb 2020 10:09:44 +1300
Subject: [PATCH] #1955 - mapToScalar - Add SqlQuery.mapToScalar( <class>
 ).findOne() / findList() ... to deprecate findSingleAttribute()

---
 src/main/java/io/ebean/SqlQuery.java          | 89 ++++++++++++++-----
 .../querydefn/DefaultRelationalQuery.java     | 29 ++++++
 .../java/org/tests/basic/TestTransient.java   | 15 ++--
 .../org/tests/basic/type/TestSqlRowUUID.java  |  2 +-
 .../tests/query/sqlquery/SqlQueryTests.java   | 16 ++--
 .../tests/update/TestSqlUpdateExceptions.java |  3 +-
 6 files changed, 116 insertions(+), 38 deletions(-)

diff --git a/src/main/java/io/ebean/SqlQuery.java b/src/main/java/io/ebean/SqlQuery.java
index e0a834867..634538610 100644
--- a/src/main/java/io/ebean/SqlQuery.java
+++ b/src/main/java/io/ebean/SqlQuery.java
@@ -125,39 +125,36 @@ public interface SqlQuery extends Serializable {
   Optional<SqlRow> findOneOrEmpty();
 
   /**
-   * Execute the query returning a single scalar attribute.
-   * <pre>@{code
+   * Deprecated - migrate to <code>.mapToScalar(attributeType).findOne()</code>.
+   * <pre>{@code
    *
-   *   String sql = "select max(unit_price) from o_order_detail where order_qty > ?";
-   *
-   *   BigDecimal maxPrice = DB.sqlQuery(sql)
-   *     .setParameter(42)
-   *     .findSingleAttribute(BigDecimal.class);
-   *
-   * }</pre>
-   *
-   * <p>
-   * The attributeType can be any scalar type that Ebean supports (includes javax time types, Joda types etc).
-   * </p>
-   *
-   * @param attributeType The type of the returned value
+   *    .mapToScalar(BigDecimal.class)
+   *    .findOne();
+   * }
    */
+  @Deprecated
   <T> T findSingleAttribute(Class<T> attributeType);
 
   /**
-   * Execute the query returning a single BigDecimal value.
-   * <p>
-   * This is an alias for <code>findSingleAttribute(BigDecimal.class)</code>
-   * </p>
+   * Deprecated - migrate to <code>.mapToScalar(BigDecimal.class).findOne()</code>.
+   * <pre>{@code
+   *
+   *    .mapToScalar(BigDecimal.class)
+   *    .findOne();
+   * }
    */
+  @Deprecated
   BigDecimal findSingleDecimal();
 
   /**
-   * Execute the query returning a single Long value.
-   * <p>
-   * This is an alias for <code>findSingleAttribute(Long.class)</code>
-   * </p>
+   * Deprecated - migrate to <code>.mapToScalar(Long.class).findOne()</code>.
+   * <pre>{@code
+   *
+   *    .mapToScalar(Long.class)
+   *    .findOne();
+   * }
    */
+  @Deprecated
   Long findSingleLong();
 
   /**
@@ -293,4 +290,50 @@ public interface SqlQuery extends Serializable {
    */
   SqlQuery setBufferFetchSizeHint(int bufferFetchSizeHint);
 
+  /**
+   * The query result maps to a single scalar value like Long, BigDecimal,
+   * String, UUID, OffsetDateTime etc.
+   * <p>
+   * Any scalar type Ebean is aware of can be used including java time
+   * types like Instant, LocalDate, OffsetDateTime, UUID, Inet, Cdir etc.
+   *
+   * <pre>{@code
+   *
+   *   String sql = " select min(updtime) from o_order_detail " +
+   *                " where unit_price > ? and updtime is not null ";
+   *
+   *   OffsetDateTime minCreated = DB.sqlQuery(sql)
+   *     .setParameter(42)
+   *     .mapToScalar(OffsetDateTime.class)
+   *     .findOne();
+   *
+   * }</pre>
+   *
+   * @param attributeType The type the result is returned as
+   * @return The query to execute via findOne() findList() etc
+   */
+  <T> ScalarQuery<T> mapToScalar(Class<T> attributeType);
+
+  /**
+   * Query mapping to single scalar values.
+   *
+   * @param <T> The type of the scalar values
+   */
+  interface ScalarQuery<T> {
+
+    /**
+     * Return the single value.
+     */
+    T findOne();
+
+    /**
+     * Return the single value that is optional.
+     */
+    Optional<T> findOneOrEmpty();
+
+    /**
+     * Return the list of values.
+     */
+    List<T> findList();
+  }
 }
diff --git a/src/main/java/io/ebeaninternal/server/querydefn/DefaultRelationalQuery.java b/src/main/java/io/ebeaninternal/server/querydefn/DefaultRelationalQuery.java
index 2c21b7b18..aa29bce24 100644
--- a/src/main/java/io/ebeaninternal/server/querydefn/DefaultRelationalQuery.java
+++ b/src/main/java/io/ebeaninternal/server/querydefn/DefaultRelationalQuery.java
@@ -2,6 +2,7 @@ package io.ebeaninternal.server.querydefn;
 
 import io.ebean.RowConsumer;
 import io.ebean.RowMapper;
+import io.ebean.SqlQuery;
 import io.ebean.SqlRow;
 import io.ebeaninternal.api.BindParams;
 import io.ebeaninternal.api.SpiEbeanServer;
@@ -207,4 +208,32 @@ public class DefaultRelationalQuery implements SpiSqlQuery {
     return query;
   }
 
+  @Override
+  public <T> ScalarQuery<T> mapToScalar(Class<T> attributeType) {
+    return new Scalar(attributeType);
+  }
+
+  private class Scalar<T> implements SqlQuery.ScalarQuery<T> {
+
+    private final Class<T> type;
+
+    Scalar(Class<T> type) {
+      this.type = type;
+    }
+
+    @Override
+    public T findOne() {
+      return findSingleAttribute(type);
+    }
+
+    @Override
+    public Optional<T> findOneOrEmpty() {
+      return Optional.ofNullable(findOne());
+    }
+
+    @Override
+    public List<T> findList() {
+      return findSingleAttributeList(type);
+    }
+  }
 }
diff --git a/src/test/java/org/tests/basic/TestTransient.java b/src/test/java/org/tests/basic/TestTransient.java
index 886695bae..428896ac1 100644
--- a/src/test/java/org/tests/basic/TestTransient.java
+++ b/src/test/java/org/tests/basic/TestTransient.java
@@ -7,11 +7,12 @@ import org.junit.Test;
 import org.tests.model.basic.Customer;
 
 import java.sql.Types;
+import java.util.Optional;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 public class TestTransient extends BaseTestCase {
@@ -65,34 +66,34 @@ public class TestTransient extends BaseTestCase {
     int rows = DB.createUpdate(Customer.class, updateStmt)
       .setParameter("id", custId).execute();
     assertEquals(1, rows);
-    assertEquals("testTrans2", findNote(custId));
+    assertEquals("testTrans2", findNote(custId).get());
 
     rows = DB.createUpdate(Customer.class, "update customer set smallnote = ? where id = ?")
       .setNull(1, Types.VARCHAR)
       .setParameter(2, custId).execute();
     assertEquals(1, rows);
-    assertNull(findNote(custId));
+    assertThat(findNote(custId)).isEmpty();
 
     rows = DB.createUpdate(Customer.class, "update customer set smallnote = ? where id = ?")
       .setParameter(1, "Foo")
       .setParameter(2, custId).execute();
     assertEquals(1, rows);
-    assertEquals("Foo", findNote(custId));
+    assertEquals("Foo", findNote(custId).get());
 
     rows = DB.createUpdate(Customer.class, "update customer set smallnote = :name where id = :id")
       .setNullParameter("name", Types.VARCHAR)
       .setParameter("id", custId).execute();
     assertEquals(1, rows);
-    assertNull(findNote(custId));
+    assertThat(findNote(custId)).isEmpty();
 
     // cleanup
     DB.delete(Customer.class, custId);
   }
 
-  private String findNote(Integer custId) {
+  private Optional<String> findNote(Integer custId) {
     return DB.sqlQuery("select smallnote from o_customer where id = ?")
         .setParameter(custId)
-        .findSingleAttribute(String.class);
+        .mapToScalar(String.class).findOneOrEmpty();
   }
 
 }
diff --git a/src/test/java/org/tests/basic/type/TestSqlRowUUID.java b/src/test/java/org/tests/basic/type/TestSqlRowUUID.java
index f2e60c16b..77b67724a 100644
--- a/src/test/java/org/tests/basic/type/TestSqlRowUUID.java
+++ b/src/test/java/org/tests/basic/type/TestSqlRowUUID.java
@@ -39,7 +39,7 @@ public class TestSqlRowUUID extends BaseTestCase {
 
     SqlQuery q2 = DB.sqlQuery("select id from tuuid_entity where id = :id");
     q2.setParameter("id", e.getId());
-    UUID value = q2.findSingleAttribute(UUID.class);
+    UUID value = q2.mapToScalar(UUID.class).findOne();
 
     assertThat(value).isEqualTo(e.getId());
 
diff --git a/src/test/java/org/tests/query/sqlquery/SqlQueryTests.java b/src/test/java/org/tests/query/sqlquery/SqlQueryTests.java
index 2631cf405..308e350ff 100644
--- a/src/test/java/org/tests/query/sqlquery/SqlQueryTests.java
+++ b/src/test/java/org/tests/query/sqlquery/SqlQueryTests.java
@@ -34,7 +34,8 @@ public class SqlQueryTests extends BaseTestCase {
 
     List<BigDecimal> lineAmounts = DB.sqlQuery(sql)
       .setParameter(3)
-      .findSingleAttributeList(BigDecimal.class);
+      .mapToScalar(BigDecimal.class)
+      .findList();
 
     assertThat(lineAmounts).isNotEmpty();
   }
@@ -48,7 +49,8 @@ public class SqlQueryTests extends BaseTestCase {
 
     BigDecimal maxPrice = DB.sqlQuery(sql)
       .setParameter(1, 2)
-      .findSingleDecimal();
+      .mapToScalar(BigDecimal.class)
+      .findOne();
 
     assertThat(maxPrice).isNotNull();
   }
@@ -62,7 +64,8 @@ public class SqlQueryTests extends BaseTestCase {
 
     BigDecimal maxPrice = DB.sqlQuery(sql)
       .setParameter(2)
-      .findSingleAttribute(BigDecimal.class);
+      .mapToScalar(BigDecimal.class)
+      .findOne();
 
     assertThat(maxPrice).isNotNull();
   }
@@ -76,7 +79,8 @@ public class SqlQueryTests extends BaseTestCase {
 
     long count = DB.sqlQuery(sql)
       .setParameter(1, 2)
-      .findSingleLong();
+      .mapToScalar(Long.class)
+      .findOne();
 
     assertThat(count).isGreaterThan(0);
   }
@@ -91,7 +95,7 @@ public class SqlQueryTests extends BaseTestCase {
 
     long count = DB.sqlQuery(sql)
       .setParameter(1, 2)
-      .findSingleAttribute(Long.class);
+      .mapToScalar(Long.class).findOne();
 
     assertThat(count).isGreaterThan(0);
   }
@@ -105,7 +109,7 @@ public class SqlQueryTests extends BaseTestCase {
 
     OffsetDateTime minCreated = DB.sqlQuery(sql)
       .setParameter(1, 2)
-      .findSingleAttribute(OffsetDateTime.class);
+      .mapToScalar(OffsetDateTime.class).findOne();
 
     assertThat(minCreated).isBefore(OffsetDateTime.now());
   }
diff --git a/src/test/java/org/tests/update/TestSqlUpdateExceptions.java b/src/test/java/org/tests/update/TestSqlUpdateExceptions.java
index 4bca88ea3..8632a9778 100644
--- a/src/test/java/org/tests/update/TestSqlUpdateExceptions.java
+++ b/src/test/java/org/tests/update/TestSqlUpdateExceptions.java
@@ -27,7 +27,8 @@ public class TestSqlUpdateExceptions extends BaseTestCase {
 
     UUID foundId = DB.sqlQuery("select id from uuone where id = ?")
       .setParameters(id)
-      .findSingleAttribute(UUID.class);
+      .mapToScalar(UUID.class)
+      .findOne();
 
     assertThat(foundId).isEqualTo(id);
   }