FIX: Cache exist query results

ebean-core/src/main/java/io/ebeaninternal/api/SpiQuery.java

@@ -81,6 +81,11 @@ public interface SpiQuery<T> extends Query<T>, SpiQueryFetch, TxnProfileEventCod
      */
     ID_LIST(FIND_ID_LIST, "findIds"),
 
+    /**
+     * Find exists.
+     */
+    EXISTS(FIND_EXISTS, "exists"),
+
     /**
      * Find single attribute.
      */

ebean-core/src/main/java/io/ebeaninternal/api/TxnProfileEventCodes.java

@@ -26,6 +26,7 @@ public interface TxnProfileEventCodes {
   String FIND_MANY = "fm";
   String FIND_ITERATE = "fe";
   String FIND_ID_LIST = "fi";
+  String FIND_EXISTS = "ex";
   String FIND_ATTRIBUTE = "fa";
   String FIND_COUNT = "fc";
   String FIND_SUBQUERY = "fs";

ebean-core/src/main/java/io/ebeaninternal/server/core/DefaultServer.java

@@ -1291,7 +1291,12 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
   @Override
   public <T> boolean exists(Query<T> ormQuery, Transaction transaction) {
     Query<T> ormQueryCopy = ormQuery.copy().setMaxRows(1);
-    SpiOrmQueryRequest<?> request = createQueryRequest(Type.ID_LIST, ormQueryCopy, transaction);
+    SpiOrmQueryRequest<?> request = createQueryRequest(Type.EXISTS, ormQueryCopy, transaction);
+    List<Object> ids = request.getFromQueryCache();
+    if (ids != null) {
+      return !ids.isEmpty();
+    }
+
     try {
       request.initTransIfRequired();
       return !request.findIds().isEmpty();

ebean-core/src/test/java/org/tests/cache/TestQueryCache.java

@@ -3,6 +3,7 @@ package org.tests.cache;
 import io.ebean.BaseTestCase;
 import io.ebean.CacheMode;
 import io.ebean.DB;
+import io.ebean.Ebean;
 import io.ebean.ExpressionList;
 import io.ebean.bean.BeanCollection;
 import io.ebean.cache.ServerCache;
@@ -135,6 +136,43 @@ public class TestQueryCache extends BaseTestCase {
     assertThat(sql).hasSize(1);
   }
 
+  @Test
+  public void exists() {
+
+    new EColAB("06", "exists").save();
+    new EColAB("07", "exists").save();
+
+    LoggedSqlCollector.start();
+
+    boolean exists0 = Ebean.find(EColAB.class)
+      .setUseQueryCache(CacheMode.ON)
+      .where()
+      .eq("columnB", "exists")
+      .exists();
+
+    boolean exists1 = Ebean.find(EColAB.class)
+      .setUseQueryCache(CacheMode.ON)
+      .where()
+      .eq("columnB", "exists")
+      .exists();
+
+    List<String> sql = LoggedSqlCollector.stop();
+
+    assertThat(exists0).isEqualTo(exists1);
+    assertThat(sql).hasSize(1);
+
+    // and now, ensure that we hit the database
+    LoggedSqlCollector.start();
+    boolean exists2 = Ebean.find(EColAB.class)
+      .setUseQueryCache(CacheMode.OFF)
+      .where()
+      .eq("columnB", "exists")
+      .exists();
+    assertThat(exists2).isEqualTo(exists1);
+    sql = LoggedSqlCollector.stop();
+    assertThat(sql).hasSize(1);
+  }
+
   @Test
   public void findCountDifferentQueries() {