Checks and tests for invalid case expressions

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/select/SearchedCaseDSL.java

@@ -20,6 +20,7 @@
 import java.util.List;
 
 import org.mybatis.dynamic.sql.AndOrCriteriaGroup;
+import org.mybatis.dynamic.sql.BasicColumn;
 import org.mybatis.dynamic.sql.BindableColumn;
 import org.mybatis.dynamic.sql.ColumnAndConditionCriterion;
 import org.mybatis.dynamic.sql.CriteriaGroup;
@@ -63,12 +64,12 @@ private WhenDSL initialize(SqlCriterion sqlCriterion) {
         return new WhenDSL(sqlCriterion);
     }
 
-    public SearchedCaseDSL elseConstant(String elseValue) {
+    public SearchedCaseEnder elseConstant(String elseValue) {
         this.elseValue = elseValue;
-        return this;
+        return new SearchedCaseEnder();
     }
 
-    public SearchedCaseModel end() {
+    public BasicColumn end() {
         return new SearchedCaseModel.Builder()
                 .withElseValue(elseValue)
                 .withWhenConditions(whenConditions)
@@ -91,6 +92,12 @@ protected WhenDSL getThis() {
         }
     }
 
+    public class SearchedCaseEnder {
+        public BasicColumn end() {
+            return SearchedCaseDSL.this.end();
+        }
+    }
+
     public static SearchedCaseDSL searchedCase() {
         return new SearchedCaseDSL();
     }

src/main/java/org/mybatis/dynamic/sql/select/SearchedCaseModel.java

@@ -28,6 +28,7 @@
 import org.mybatis.dynamic.sql.render.RenderingContext;
 import org.mybatis.dynamic.sql.select.render.SearchedCaseRenderer;
 import org.mybatis.dynamic.sql.util.FragmentAndParameters;
+import org.mybatis.dynamic.sql.util.Validator;
 
 public class SearchedCaseModel implements BasicColumn {
     private final List<SearchedWhenCondition> whenConditions;
@@ -38,6 +39,7 @@ private SearchedCaseModel(Builder builder) {
         whenConditions = builder.whenConditions;
         alias = builder.alias;
         elseValue = builder.elseValue;
+        Validator.assertNotEmpty(whenConditions, "ERROR.40"); //$NON-NLS-1$
     }
 
     public Stream<SearchedWhenCondition> whenConditions() {
@@ -74,8 +76,8 @@ public String thenValue() {
             return thenValue;
         }
 
-        protected SearchedWhenCondition(SqlCriterion initialCriterion, List<AndOrCriteriaGroup> subCriteria,
-                                        String thenValue) {
+        public SearchedWhenCondition(SqlCriterion initialCriterion, List<AndOrCriteriaGroup> subCriteria,
+                                     String thenValue) {
             super(initialCriterion, subCriteria);
             this.thenValue = Objects.requireNonNull(thenValue);
         }

src/main/java/org/mybatis/dynamic/sql/select/SimpleCaseDSL.java

@@ -20,6 +20,7 @@
 import java.util.List;
 import java.util.Objects;
 
+import org.mybatis.dynamic.sql.BasicColumn;
 import org.mybatis.dynamic.sql.BindableColumn;
 import org.mybatis.dynamic.sql.VisitableCondition;
 
@@ -43,12 +44,12 @@ public WhenFinisher when(VisitableCondition<T> condition,
         return new WhenFinisher(condition, subsequentConditions);
     }
 
-    public SimpleCaseDSL<T> elseConstant(String value) {
+    public SimpleCaseEnder elseConstant(String value) {
         elseValue = value;
-        return this;
+        return new SimpleCaseEnder();
     }
 
-    public SimpleCaseModel<T> end() {
+    public BasicColumn end() {
         return new SimpleCaseModel.Builder<T>()
                 .withColumn(column)
                 .withWhenConditions(whenConditions)
@@ -70,6 +71,12 @@ public SimpleCaseDSL<T> thenConstant(String value) {
         }
     }
 
+    public class SimpleCaseEnder {
+        public BasicColumn end() {
+            return SimpleCaseDSL.this.end();
+        }
+    }
+
     public static <T> SimpleCaseDSL<T> simpleCase(BindableColumn<T> column) {
         return new SimpleCaseDSL<>(column);
     }

src/main/java/org/mybatis/dynamic/sql/select/SimpleCaseModel.java

@@ -27,6 +27,7 @@
 import org.mybatis.dynamic.sql.render.RenderingContext;
 import org.mybatis.dynamic.sql.select.render.SimpleCaseRenderer;
 import org.mybatis.dynamic.sql.util.FragmentAndParameters;
+import org.mybatis.dynamic.sql.util.Validator;
 
 public class SimpleCaseModel<T> implements BasicColumn {
     private final BindableColumn<T> column;
@@ -39,6 +40,7 @@ private SimpleCaseModel(Builder<T> builder) {
         whenConditions = builder.whenConditions;
         elseValue = builder.elseValue;
         alias = builder.alias;
+        Validator.assertNotEmpty(whenConditions, "ERROR.40"); //$NON-NLS-1$
     }
 
     public BindableColumn<T> column() {
@@ -85,7 +87,7 @@ public Object thenValue() {
             return thenValue;
         }
 
-        protected SimpleWhenCondition(List<VisitableCondition<T>> conditions, String thenValue) {
+        public SimpleWhenCondition(List<VisitableCondition<T>> conditions, String thenValue) {
             this.conditions.addAll(conditions);
             this.thenValue = Objects.requireNonNull(thenValue);
         }

src/main/java/org/mybatis/dynamic/sql/select/render/SimpleCaseRenderer.java

@@ -25,6 +25,7 @@
 import org.mybatis.dynamic.sql.select.SimpleCaseModel;
 import org.mybatis.dynamic.sql.util.FragmentAndParameters;
 import org.mybatis.dynamic.sql.util.FragmentCollector;
+import org.mybatis.dynamic.sql.util.Validator;
 import org.mybatis.dynamic.sql.where.render.DefaultConditionVisitor;
 
 public class SimpleCaseRenderer<T> {
@@ -83,6 +84,7 @@ private FragmentAndParameters renderConditions(SimpleCaseModel.SimpleWhenConditi
     }
 
     private FragmentAndParameters renderCondition(VisitableCondition<T> condition) {
+        Validator.assertTrue(condition.shouldRender(renderingContext), "ERROR.39"); //$NON-NLS-1$
         return condition.accept(conditionVisitor);
     }
 

src/main/resources/org/mybatis/dynamic/sql/util/messages.properties

@@ -55,5 +55,6 @@ ERROR.35=Multi-select statements must have at least one "union" or "union all" e
 ERROR.36=You must either implement the "render" or  "renderWithTableAlias" method in a column or function
 ERROR.37=The "{0}" function does not support conditions that fail to render
 ERROR.38=Bound values cannot be aliased
-ERROR.39=When clauses in searched case expressions must render
+ERROR.39=When clauses in case expressions must render (optional conditions are not supported)
+ERROR.40=Case expressions must have at least one "when" clause
 INTERNAL.ERROR=Internal Error {0}

src/test/java/examples/animal/data/CaseExpressionTest.java

@@ -310,14 +310,40 @@ void testSimpleCaseNoElse() {
     }
 
     @Test
-    void testInvalidCase() {
+    void testInvalidSearchedCaseNoConditionsRender() {
         SelectModel model = select(animalName, searchedCase()
-                .when(animalName,isEqualToWhenPresent((String) null)).thenConstant("Fred").end())
+                .when(animalName, isEqualToWhenPresent((String) null)).thenConstant("Fred").end())
                 .from(animalData)
                 .build();
 
         assertThatExceptionOfType(InvalidSqlException.class)
                 .isThrownBy(() -> model.render(RenderingStrategies.MYBATIS3))
                 .withMessage(Messages.getString("ERROR.39"));
     }
+
+    @Test
+    void testInvalidSimpleCaseNoConditionsRender() {
+        SelectModel model = select(simpleCase(animalName)
+                .when(isEqualToWhenPresent((String) null)).thenConstant("Fred").end())
+                .from(animalData)
+                .build();
+
+        assertThatExceptionOfType(InvalidSqlException.class)
+                .isThrownBy(() -> model.render(RenderingStrategies.MYBATIS3))
+                .withMessage(Messages.getString("ERROR.39"));
+    }
+
+    @Test
+    void testInvalidSearchedCaseNoWhenConditions() {
+        assertThatExceptionOfType(InvalidSqlException.class).isThrownBy(
+                () -> searchedCase().end()
+        ).withMessage(Messages.getString("ERROR.40"));
+    }
+
+    @Test
+    void testInvalidSimpleCaseNoWhenConditions() {
+        assertThatExceptionOfType(InvalidSqlException.class).isThrownBy(
+                () -> simpleCase(id).end()
+        ).withMessage(Messages.getString("ERROR.40"));
+    }
 }