Add optional variantRecordLookupFunction to BackendVariantsConfig and validation of same; refactor up some shared backend code into BackendVariantsUtil

qqq-backend-core/src/test/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidatorTest.java

@@ -103,6 +103,7 @@ import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwith
 import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.LoadViaDeleteStep;
 import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.StreamedETLWithFrontendProcess;
 import com.kingsrook.qqq.backend.core.utils.TestUtils;
+import com.kingsrook.qqq.backend.core.utils.lambdas.UnsafeFunction;
 import org.junit.jupiter.api.Test;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
@@ -246,6 +247,79 @@ public class QInstanceValidatorTest extends BaseTest
                .withOptionsTableName(TestUtils.TABLE_NAME_PERSON)
                .withBackendSettingSourceFieldNameMap(Map.of(setting, "noSuchField")))),
          "Unrecognized fieldName [noSuchField] in backendSettingSourceFieldNameMap");
+
+      assertValidationFailureReasons((qInstance) -> qInstance.addBackend(new QBackendMetaData()
+            .withName("variant")
+            .withUsesVariants(true)
+            .withBackendVariantsConfig(new BackendVariantsConfig()
+               .withVariantTypeKey("myVariant")
+               .withOptionsTableName(TestUtils.TABLE_NAME_PERSON)
+               .withVariantRecordLookupFunction(new QCodeReference(CustomizerThatIsNotOfTheRightBaseClass.class))
+               .withBackendSettingSourceFieldNameMap(Map.of(setting, "no-field-but-okay-custom-supplier"))
+            )),
+         "VariantRecordSupplier in backendVariantsConfig in backend [variant]: CodeReference is not any of the expected types: com.kingsrook.qqq.backend.core.utils.lambdas.UnsafeFunction, java.util.function.Function");
+
+      assertValidationSuccess((qInstance) -> qInstance.addBackend(new QBackendMetaData()
+         .withName("variant")
+         .withUsesVariants(true)
+         .withBackendVariantsConfig(new BackendVariantsConfig()
+            .withVariantTypeKey("myVariant")
+            .withOptionsTableName(TestUtils.TABLE_NAME_PERSON)
+            .withBackendSettingSourceFieldNameMap(Map.of(setting, "firstName"))
+         )));
+
+      assertValidationSuccess((qInstance) -> qInstance.addBackend(new QBackendMetaData()
+         .withName("variant")
+         .withUsesVariants(true)
+         .withBackendVariantsConfig(new BackendVariantsConfig()
+            .withVariantTypeKey("myVariant")
+            .withOptionsTableName(TestUtils.TABLE_NAME_PERSON)
+            .withVariantRecordLookupFunction(new QCodeReference(VariantRecordFunction.class))
+            .withBackendSettingSourceFieldNameMap(Map.of(setting, "no-field-but-okay-custom-supplier"))
+         )));
+
+      assertValidationSuccess((qInstance) -> qInstance.addBackend(new QBackendMetaData()
+         .withName("variant")
+         .withUsesVariants(true)
+         .withBackendVariantsConfig(new BackendVariantsConfig()
+            .withVariantTypeKey("myVariant")
+            .withOptionsTableName(TestUtils.TABLE_NAME_PERSON)
+            .withVariantRecordLookupFunction(new QCodeReference(VariantRecordUnsafeFunction.class))
+            .withBackendSettingSourceFieldNameMap(Map.of(setting, "no-field-but-okay-custom-supplier"))
+         )));
+   }
+
+
+
+   /***************************************************************************
+    **
+    ***************************************************************************/
+   public static class VariantRecordFunction implements Function<Serializable, QRecord>
+   {
+      /***************************************************************************
+       **
+       ***************************************************************************/
+      @Override
+      public QRecord apply(Serializable serializable)
+      {
+         return null;
+      }
+   }
+
+
+   /***************************************************************************
+    **
+    ***************************************************************************/
+   public static class VariantRecordUnsafeFunction implements UnsafeFunction<Serializable, QRecord, QException>
+   {
+      /***************************************************************************
+       **
+       ***************************************************************************/
+      @Override
+      public QRecord apply(Serializable serializable) throws QException
+      {
+         return null;
+      }
    }
 
 
@@ -2437,7 +2511,7 @@ public class QInstanceValidatorTest extends BaseTest
       {
          int noOfReasons = actualReasons == null ? 0 : actualReasons.size();
          assertEquals(expectedReasons.length, noOfReasons, "Expected number of validation failure reasons.\nExpected reasons: " + String.join(",", expectedReasons)
-                                                           + "\nActual reasons: " + (noOfReasons > 0 ? String.join("\n", actualReasons) : "--"));
+            + "\nActual reasons: " + (noOfReasons > 0 ? String.join("\n", actualReasons) : "--"));
       }
 
       for(String reason : expectedReasons)

qqq-backend-core/src/test/java/com/kingsrook/qqq/backend/core/model/metadata/variants/BackendVariantsUtilTest.java

@@ -0,0 +1,100 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2025.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.model.metadata.variants;
+
+
+import java.util.Map;
+import com.kingsrook.qqq.backend.core.BaseTest;
+import com.kingsrook.qqq.backend.core.context.QContext;
+import com.kingsrook.qqq.backend.core.exceptions.QException;
+import com.kingsrook.qqq.backend.core.model.data.QRecord;
+import com.kingsrook.qqq.backend.core.model.metadata.QBackendMetaData;
+import com.kingsrook.qqq.backend.core.utils.TestUtils;
+import org.junit.jupiter.api.Test;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+
+/*******************************************************************************
+ ** Unit test for BackendVariantsUtil 
+ *******************************************************************************/
+class BackendVariantsUtilTest extends BaseTest
+{
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void testGetVariantId() throws QException
+   {
+      QBackendMetaData myBackend = getBackendMetaData();
+
+      assertThatThrownBy(() -> BackendVariantsUtil.getVariantId(myBackend))
+         .hasMessageContaining("Could not find Backend Variant information in session under key 'yourSelectedShape' for Backend 'TestBackend'");
+
+      QContext.getQSession().setBackendVariants(Map.of("yourSelectedShape", 1701));
+      assertEquals(1701, BackendVariantsUtil.getVariantId(myBackend));
+   }
+
+
+
+   /***************************************************************************
+    **
+    ***************************************************************************/
+   private static QBackendMetaData getBackendMetaData()
+   {
+      QBackendMetaData myBackend = new QBackendMetaData()
+         .withName("TestBackend")
+         .withUsesVariants(true)
+         .withBackendVariantsConfig(new BackendVariantsConfig()
+            .withOptionsTableName(TestUtils.TABLE_NAME_SHAPE)
+            .withVariantTypeKey("yourSelectedShape"));
+      return myBackend;
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void testGetVariantRecord() throws QException
+   {
+      QBackendMetaData myBackend = getBackendMetaData();
+
+      TestUtils.insertDefaultShapes(QContext.getQInstance());
+
+      assertThatThrownBy(() -> BackendVariantsUtil.getVariantRecord(myBackend))
+         .hasMessageContaining("Could not find Backend Variant information in session under key 'yourSelectedShape' for Backend 'TestBackend'");
+
+      QContext.getQSession().setBackendVariants(Map.of("yourSelectedShape", 1701));
+      assertThatThrownBy(() -> BackendVariantsUtil.getVariantRecord(myBackend))
+         .hasMessageContaining("Could not find Backend Variant in table shape with id '1701'");
+
+      QContext.getQSession().setBackendVariants(Map.of("yourSelectedShape", 1));
+      QRecord variantRecord = BackendVariantsUtil.getVariantRecord(myBackend);
+      assertEquals(1, variantRecord.getValueInteger("id"));
+      assertNotNull(variantRecord.getValue("name"));
+   }
+
+}