#1645 - ENH: Add expression rawOrEmpty() ... as a convenience for conditionally added a raw expression

src/main/java/io/ebean/ExpressionList.java

@@ -1282,6 +1282,68 @@ public interface ExpressionList<T> {
    */
   ExpressionList<T> raw(String raw);
 
+  /**
+   * Only add the raw expression if the values is not null or empty.
+   * <p>
+   * This is a pure convenience expression to make it nicer to deal with the pattern where we use
+   * raw() expression with a subquery and only want to add the subquery predicate when the collection
+   * of values is not empty.
+   * </p>
+   * <h3>Without inOrEmpty()</h3>
+   * <pre>{@code
+   *
+   *   query.where() // add some predicates
+   *     .eq("status", Status.NEW);
+   *
+   *   // common pattern - we can use rawOrEmpty() instead
+   *   if (orderIds != null && !orderIds.isEmpty()) {
+   *     query.where().raw("t0.customer_id in (select o.customer_id from orders o where o.id in (?1))", orderIds);
+   *   }
+   *
+   *   query.findList();
+   *
+   * }</pre>
+   *
+   * <h3>Using rawOrEmpty()</h3>
+   * Note that in the example below we use the <code>?1</code> bind parameter to get  "parameter expansion"
+   * for each element in the collection.
+   *
+   * <pre>{@code
+   *
+   *   query.where()
+   *     .eq("status", Status.NEW)
+   *     // only add the expression if orderIds is not empty
+   *     .rawOrEmpty("t0.customer_id in (select o.customer_id from orders o where o.id in (?1))", orderIds);
+   *     .findList();
+   *
+   * }</pre>
+   *
+   * <h3>Postgres ANY</h3>
+   * With Postgres we would often use the SQL <code>ANY</code> expression and array parameter binding
+   * rather than <code>IN</code>.
+   *
+   * <pre>{@code
+   *
+   *   query.where()
+   *     .eq("status", Status.NEW)
+   *     .rawOrEmpty("t0.customer_id in (select o.customer_id from orders o where o.id = any(?))", orderIds);
+   *     .findList();
+   *
+   * }</pre>
+   * <p>
+   *   Note that we need to cast the Postgres array for UUID types like:
+   * </p>
+   * <pre>{@code
+   *
+   *   " ... = any(?::uuid[])"
+   *
+   * }</pre>
+   *
+   * @param raw The raw expression that is typically a subquery
+   * @param values The values which is typically a list or set of id values.
+   */
+  ExpressionList<T> rawOrEmpty(String raw, Collection<Object> values);
+
   /**
    * Add a match expression.
    *

src/main/java/io/ebeaninternal/server/expression/DefaultExpressionList.java

@@ -914,7 +914,9 @@ public class DefaultExpressionList<T> implements SpiExpressionList<T> {
 
   @Override
   public ExpressionList<T> inOrEmpty(String propertyName, Collection<?> values) {
-    add(expr.inOrEmpty(propertyName, values));
+    if (notEmpty(values)) {
+      add(expr.in(propertyName, values));
+    }
     return this;
   }
 
@@ -1074,6 +1076,18 @@ public class DefaultExpressionList<T> implements SpiExpressionList<T> {
     return this;
   }
 
+  @Override
+  public ExpressionList<T> rawOrEmpty(String raw, Collection<Object> values) {
+    if (notEmpty(values)) {
+      add(expr.raw(raw, values));
+    }
+    return this;
+  }
+
+  private boolean notEmpty(Collection<?> values) {
+    return values != null && !values.isEmpty();
+  }
+
   @Override
   public ExpressionList<T> startsWith(String propertyName, String value) {
     add(expr.startsWith(propertyName, value));

src/main/java/io/ebeaninternal/server/expression/JunctionExpression.java

@@ -807,6 +807,11 @@ class JunctionExpression<T> implements SpiJunction<T>, SpiExpression, Expression
     return exprList.raw(raw, values);
   }
 
+  @Override
+  public ExpressionList<T> rawOrEmpty(String raw, Collection<Object> values) {
+    return exprList.rawOrEmpty(raw, values);
+  }
+
   @Override
   public ExpressionList<T> raw(String raw) {
     return exprList.raw(raw);

src/test/java/org/tests/query/TestWhereIn.java

@@ -53,7 +53,7 @@ public class TestWhereIn extends BaseTestCase {
       .where().inOrEmpty("customer.billingAddress.id", new ArrayList<>()).query();
 
     query.findList();
-    assertThat(sqlOf(query)).isEqualTo("select t0.id from o_order t0 where 1=1");
+    assertThat(sqlOf(query)).isEqualTo("select t0.id from o_order t0");
   }
 
   @Test
@@ -79,10 +79,9 @@ public class TestWhereIn extends BaseTestCase {
       .where().inOrEmpty("code", null).query();
 
     query.findList();
-    assertThat(sqlOf(query)).contains("where 1=1");
+    assertThat(sqlOf(query)).isEqualTo("select t0.code, t0.name from o_country t0");
   }
 
-
   @Test
   public void testInOrEmpty_when_empty() {
 
@@ -92,7 +91,7 @@ public class TestWhereIn extends BaseTestCase {
       .where().inOrEmpty("code", new ArrayList<>()).query();
 
     query.findList();
-    assertThat(sqlOf(query)).contains("where 1=1");
+    assertThat(sqlOf(query)).isEqualTo("select t0.code, t0.name from o_country t0");
   }
 
   @Test

src/test/java/org/tests/query/TestWhereRawClause.java

@@ -6,6 +6,7 @@ import io.ebean.Expr;
 import io.ebean.Query;
 import io.ebean.annotation.ForPlatform;
 import io.ebean.annotation.Platform;
+import org.ebeantest.LoggedSqlCollector;
 import org.junit.Test;
 import org.tests.model.basic.Customer;
 import org.tests.model.basic.Order;
@@ -13,6 +14,7 @@ import org.tests.model.basic.OrderDetail;
 import org.tests.model.basic.ResetBasicData;
 
 import java.sql.Timestamp;
+import java.util.Collections;
 import java.util.List;
 
 import static java.util.Arrays.asList;
@@ -65,6 +67,54 @@ public class TestWhereRawClause extends BaseTestCase {
     assertThat(sqlOf(query)).contains(" t0.id in (select c.id from o_customer c where c.name in (?,?,?))");
   }
 
+  @Test
+  public void testRawOrEmpty_when_notEmpty() {
+
+    ResetBasicData.reset();
+
+    Query<Customer> query = Ebean.find(Customer.class)
+      .select("name")
+      .where()
+      .rawOrEmpty("id in (select c.id from o_customer c where c.name in (?1))", asList("Rob", "Fiona", "Jack"))
+      .query();
+
+    List<Customer> list = query.findList();
+    assertThat(list).isNotEmpty();
+    assertThat(sqlOf(query)).contains(" t0.id in (select c.id from o_customer c where c.name in (?,?,?))");
+  }
+
+  @Test
+  public void testRawOrEmpty_when_null() {
+
+    ResetBasicData.reset();
+
+    Query<Customer> query = Ebean.find(Customer.class)
+      .select("name")
+      .where()
+      .rawOrEmpty("id in (select c.id from o_customer c where c.name in (?1))", null)
+      .query();
+
+    List<Customer> list = query.findList();
+    assertThat(list).isNotEmpty();
+    assertThat(sqlOf(query)).isEqualTo("select t0.id, t0.name from o_customer t0");
+  }
+
+  @Test
+  public void testRawOrEmpty_when_empty() {
+
+    ResetBasicData.reset();
+
+    Query<Customer> query = Ebean.find(Customer.class)
+      .select("name")
+      .where()
+      .rawOrEmpty("id in (select c.id from o_customer c where c.name in (?1))", Collections.emptySet())
+      .query();
+
+    List<Customer> list = query.findList();
+    assertThat(list).isNotEmpty();
+    assertThat(sqlOf(query)).isEqualTo("select t0.id, t0.name from o_customer t0");
+  }
+
   @Test
   public void testRaw_bindExpansion() {
 
@@ -94,6 +144,33 @@ public class TestWhereRawClause extends BaseTestCase {
     assertThat(list).isNotEmpty();
   }
 
+  @Test
+  @ForPlatform(Platform.POSTGRES)
+  public void testRawOrEmpty_PostgresArray() {
+
+    ResetBasicData.reset();
+
+    LoggedSqlCollector.start();
+
+    Ebean.find(Customer.class)
+      .select("name").where().rawOrEmpty("name = any(?)", asList("Rob", "Fiona", "Jack"))
+      .findList();
+
+    Ebean.find(Customer.class)
+      .select("name").where().rawOrEmpty("name = any(?)", asList())
+      .findList();
+
+    Ebean.find(Customer.class)
+      .select("name").where().rawOrEmpty("name = any(?)", null)
+      .findList();
+
+    List<String> sql = LoggedSqlCollector.stop();
+
+    assertThat(sql.get(0)).isEqualTo("select t0.id, t0.name from o_customer t0 where t0.name = any(?); --bind(Array[3]={Rob,Fiona,Jack})");
+    assertThat(sql.get(1)).isEqualTo("select t0.id, t0.name from o_customer t0; --bind()");
+    assertThat(sql.get(2)).isEqualTo("select t0.id, t0.name from o_customer t0; --bind()");
+  }
+
   @Test
   public void testRawWithBindParams() {