#2768 - ENH: Add eqIfPresent() - a helper expression for fluid style when some EQ are optional

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

@@ -385,7 +385,7 @@ public interface ExpressionList<T> {
 
   /**
    * Executes the query returning a set of values for a single property.
-   *
+   * <p>
    * This can be used to cache sets.
    *
    * @return a HashSet of values for the selegted property
@@ -835,6 +835,20 @@ public interface ExpressionList<T> {
    */
   ExpressionList<T> eq(String propertyName, Object value);
 
+  /**
+   * Is EQUAL TO if value is non-null and otherwise no expression is added to the query.
+   * <p>
+   * This is the EQUAL TO equivalent to {@link #inOrEmpty(String, Collection)} where the expression/predicate
+   * is only added when the value is non-null.
+   * <p>
+   * This is effectively a helper method that allows a query to be built in fluid style where some predicates are
+   * effectively optional. We can use <code>eqIfPresent()</code> rather than having a separate if block.
+   * <p>
+   * Another option is to instead globally use {@link io.ebean.config.DatabaseConfig#setExpressionEqualsWithNullAsNoop(boolean)}
+   * but that is not always desirable.
+   */
+  ExpressionList<T> eqIfPresent(String propertyName, @Nullable Object value);
+
   /**
    * Equal To or Null - property is equal to a given value or null.
    */

ebean-core/src/main/java/io/ebeaninternal/server/expression/DefaultExpressionList.java

@@ -798,6 +798,11 @@ public class DefaultExpressionList<T> implements SpiExpressionList<T> {
     return add(expr.eq(propertyName, value));
   }
 
+  @Override
+  public ExpressionList<T> eqIfPresent(String propertyName, @Nullable Object value) {
+    return value == null ? this : add(expr.eq(propertyName, value));
+  }
+
   @Override
   public ExpressionList<T> eqOrNull(String propertyName, Object value) {
     return add(expr.eqOrNull(propertyName, value));

ebean-core/src/main/java/io/ebeaninternal/server/expression/JunctionExpression.java

@@ -309,6 +309,11 @@ final class JunctionExpression<T> implements SpiJunction<T>, SpiExpression, Expr
     return exprList.eq(propertyName, value);
   }
 
+  @Override
+  public ExpressionList<T> eqIfPresent(String propertyName, @Nullable Object value) {
+    return value == null ? this : exprList.eq(propertyName, value);
+  }
+
   @Override
   public ExpressionList<T> eqOrNull(String propertyName, Object value) {
     return exprList.eqOrNull(propertyName, value);

ebean-querybean/src/main/java/io/ebean/typequery/PBaseValueEqual.java

@@ -1,5 +1,6 @@
 package io.ebean.typequery;
 
+import io.avaje.lang.Nullable;
 import io.ebean.Query;
 
 import java.util.Collection;
@@ -82,6 +83,25 @@ public abstract class PBaseValueEqual<R, T> extends TQPropertyBase<R> {
     return _root;
   }
 
+  /**
+   * Is equal to if value is non-null and otherwise no expression is added to the query.
+   * <p>
+   * That is, only add the EQUAL TO predicate if the value is not null.
+   * <p>
+   * This is the EQUAL TO equivalent to {@link #inOrEmpty(Collection)} where the expression/predicate
+   * is only added to the query when the value is non-null.
+   * <p>
+   * This is effectively a helper method that allows a query to be built in fluid style where some predicates are
+   * effectively optional. We can use <code>eqIfPresent()</code> rather than having a separate if block.
+   *
+   * @param value the equal to bind value
+   * @return the root query bean instance
+   */
+  public final R eqIfPresent(@Nullable T value) {
+    expr().eqIfPresent(_name, value);
+    return _root;
+  }
+
   /**
    * Is equal to or Null.
    *
@@ -247,7 +267,7 @@ public abstract class PBaseValueEqual<R, T> extends TQPropertyBase<R> {
   public final R isIn(Query<?> subQuery) {
     return in(subQuery);
   }
-  
+
   /**
    * Is NOT in the result of a subquery.
    *

ebean-querybean/src/test/java/org/querytest/MyInnerTest.java

@@ -1,17 +1,20 @@
 package org.querytest;
 
 import io.ebean.DB;
+import io.ebean.test.LoggedSql;
 import org.example.domain.MyInner;
 import org.example.domain.query.QMyInner;
 import org.junit.jupiter.api.Test;
 
+import java.util.List;
+import java.util.Optional;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 class MyInnerTest {
 
   @Test
   void insert_and_find() {
-
     MyInner myInner = new MyInner()
       .id(42).one("one").description("foo");
 
@@ -26,5 +29,25 @@ class MyInnerTest {
       .findOne();
 
     assertThat(found2).isNotNull();
+
+    LoggedSql.start();
+
+    MyInner found3 = new QMyInner()
+      .one.eqIfPresent("one")
+      .findOne();
+
+    assertThat(found3).isNotNull();
+
+    MyInner found4 = new QMyInner()
+      .one.eqIfPresent(null)
+      .description.eqIfPresent("foo")
+      .findOne();
+
+    assertThat(found4).isNotNull();
+
+    List<String> sql = LoggedSql.stop();
+    assertThat(sql).hasSize(2);
+    assertThat(sql.get(0)).contains("select t0.id, t0.one, t0.id, t0.one, t0.description from my_inner t0 where t0.one = ?;");
+    assertThat(sql.get(1)).contains("select t0.id, t0.one, t0.id, t0.one, t0.description from my_inner t0 where t0.description = ?;");
   }
 }

ebean-test/src/test/java/org/tests/query/TestQueryIsNull.java

@@ -23,6 +23,52 @@ public class TestQueryIsNull extends BaseTestCase {
     assertThat(query.getGeneratedSql()).contains("name is null");
   }
 
+  @Test
+  void query_defaultNullToIsNull() {
+    ResetBasicData.reset();
+
+    Query<Order> query = DB.find(Order.class).select("id, status")
+      .where().eq("status", null).query();
+    query.findList();
+
+    assertThat(query.getGeneratedSql()).isEqualTo("select t0.id, t0.status from o_order t0 where t0.status is null");
+  }
+
+  @Test
+  void query_eqIfPresent() {
+    ResetBasicData.reset();
+
+    Query<Order> query = DB.find(Order.class).select("id, status")
+      .where().eqIfPresent("status", null).query();
+    query.findList();
+
+    assertThat(query.getGeneratedSql()).isEqualTo("select t0.id, t0.status from o_order t0");
+
+    Query<Order> query1 = DB.find(Order.class).select("id, status")
+      .where().eqIfPresent("status", null).isNull("shipDate").query();
+    query1.findList();
+
+    assertThat(query1.getGeneratedSql()).isEqualTo("select t0.id, t0.status from o_order t0 where t0.ship_date is null");
+
+    Query<Order> query2 = DB.find(Order.class).select("id, status")
+      .where().isNotNull("orderDate").eqIfPresent("status", null).query();
+    query2.findList();
+
+    assertThat(query2.getGeneratedSql()).isEqualTo("select t0.id, t0.status from o_order t0 where t0.order_date is not null");
+
+    Query<Order> query3 = DB.find(Order.class).select("id, status")
+      .where().isNotNull("orderDate").eqIfPresent("status", null).isNull("shipDate").query();
+    query3.findList();
+
+    assertThat(query3.getGeneratedSql()).isEqualTo("select t0.id, t0.status from o_order t0 where t0.order_date is not null and t0.ship_date is null");
+
+    Query<Order> query4 = DB.find(Order.class).select("id, status")
+      .where().isNotNull("orderDate").eqIfPresent("status", Order.Status.NEW).isNull("shipDate").query();
+    query4.findList();
+
+    assertThat(query4.getGeneratedSql()).isEqualTo("select t0.id, t0.status from o_order t0 where t0.order_date is not null and t0.status = ? and t0.ship_date is null");
+  }
+
   @Test
   public void isNotNull_when_OneToMany_expect_existsSubquery() {
     ResetBasicData.reset();