Allow case statements in order by phrases

Author: jeffgbutler

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

@@ -71,7 +71,7 @@ public SearchedCaseEnder else_(BasicColumn column) {
         return new SearchedCaseEnder();
     }
 
-    public BasicColumn end() {
+    public SearchedCaseModel end() {
         return new SearchedCaseModel.Builder()
                 .withElseValue(elseValue)
                 .withWhenConditions(whenConditions)
@@ -100,7 +100,7 @@ protected WhenDSL getThis() {
     }
 
     public class SearchedCaseEnder {
-        public BasicColumn end() {
+        public SearchedCaseModel end() {
             return SearchedCaseDSL.this.end();
         }
     }

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

@@ -21,20 +21,23 @@
 import java.util.stream.Stream;
 
 import org.mybatis.dynamic.sql.BasicColumn;
+import org.mybatis.dynamic.sql.SortSpecification;
 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 {
+public class SearchedCaseModel implements BasicColumn, SortSpecification {
     private final List<SearchedCaseWhenCondition> whenConditions;
     private final BasicColumn elseValue;
     private final String alias;
+    private final String descendingPhrase;
 
     private SearchedCaseModel(Builder builder) {
         whenConditions = builder.whenConditions;
         alias = builder.alias;
         elseValue = builder.elseValue;
+        descendingPhrase = builder.descendingPhrase;
         Validator.assertNotEmpty(whenConditions, "ERROR.40"); //$NON-NLS-1$
     }
 
@@ -56,9 +59,24 @@ public SearchedCaseModel as(String alias) {
         return new Builder().withWhenConditions(whenConditions)
                 .withElseValue(elseValue)
                 .withAlias(alias)
+                .withDescendingPhrase(descendingPhrase)
                 .build();
     }
 
+    @Override
+    public SearchedCaseModel descending() {
+        return new Builder().withWhenConditions(whenConditions)
+                .withElseValue(elseValue)
+                .withAlias(alias)
+                .withDescendingPhrase(" DESC") //$NON-NLS-1$
+                .build();
+    }
+
+    @Override
+    public FragmentAndParameters renderForOrderBy(RenderingContext renderingContext) {
+        return render(renderingContext).mapFragment(f -> f + descendingPhrase);
+    }
+
     @Override
     public FragmentAndParameters render(RenderingContext renderingContext) {
         return new SearchedCaseRenderer(this, renderingContext).render();
@@ -68,6 +86,7 @@ public static class Builder {
         private final List<SearchedCaseWhenCondition> whenConditions = new ArrayList<>();
         private BasicColumn elseValue;
         private String alias;
+        private String descendingPhrase = ""; //$NON-NLS-1$
 
         public Builder withWhenConditions(List<SearchedCaseWhenCondition> whenConditions) {
             this.whenConditions.addAll(whenConditions);
@@ -84,6 +103,11 @@ public Builder withAlias(String alias) {
             return this;
         }
 
+        public Builder withDescendingPhrase(String descendingPhrase) {
+            this.descendingPhrase = descendingPhrase;
+            return this;
+        }
+
         public SearchedCaseModel build() {
             return new SearchedCaseModel(this);
         }

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

@@ -60,7 +60,7 @@ public SimpleCaseEnder else_(BasicColumn column) {
         return new SimpleCaseEnder();
     }
 
-    public BasicColumn end() {
+    public SimpleCaseModel<T> end() {
         return new SimpleCaseModel.Builder<T>()
                 .withColumn(column)
                 .withWhenConditions(whenConditions)
@@ -100,7 +100,7 @@ public SimpleCaseDSL<T> then(BasicColumn column) {
     }
 
     public class SimpleCaseEnder {
-        public BasicColumn end() {
+        public SimpleCaseModel<T> end() {
             return SimpleCaseDSL.this.end();
         }
     }

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

@@ -23,22 +23,25 @@
 
 import org.mybatis.dynamic.sql.BasicColumn;
 import org.mybatis.dynamic.sql.BindableColumn;
+import org.mybatis.dynamic.sql.SortSpecification;
 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 {
+public class SimpleCaseModel<T> implements BasicColumn, SortSpecification {
     private final BindableColumn<T> column;
     private final List<SimpleCaseWhenCondition<T>> whenConditions;
     private final BasicColumn elseValue;
     private final String alias;
+    private final String descendingPhrase;
 
     private SimpleCaseModel(Builder<T> builder) {
         column = Objects.requireNonNull(builder.column);
         whenConditions = builder.whenConditions;
         elseValue = builder.elseValue;
         alias = builder.alias;
+        descendingPhrase = builder.descendingPhrase;
         Validator.assertNotEmpty(whenConditions, "ERROR.40"); //$NON-NLS-1$
     }
 
@@ -66,9 +69,26 @@ public SimpleCaseModel<T> as(String alias) {
                 .withWhenConditions(whenConditions)
                 .withElseValue(elseValue)
                 .withAlias(alias)
+                .withDescendingPhrase(descendingPhrase)
                 .build();
     }
 
+    @Override
+    public SimpleCaseModel<T> descending() {
+        return new Builder<T>()
+                .withColumn(column)
+                .withWhenConditions(whenConditions)
+                .withElseValue(elseValue)
+                .withAlias(alias)
+                .withDescendingPhrase(" DESC") //$NON-NLS-1$
+                .build();
+    }
+
+    @Override
+    public FragmentAndParameters renderForOrderBy(RenderingContext renderingContext) {
+        return render(renderingContext).mapFragment(f -> f + descendingPhrase);
+    }
+
     @Override
     public FragmentAndParameters render(RenderingContext renderingContext) {
         return new SimpleCaseRenderer<>(this, renderingContext).render();
@@ -79,6 +99,7 @@ public static class Builder<T> {
         private final List<SimpleCaseWhenCondition<T>> whenConditions = new ArrayList<>();
         private BasicColumn elseValue;
         private String alias;
+        private String descendingPhrase = ""; //$NON-NLS-1$
 
         public Builder<T> withColumn(BindableColumn<T> column) {
             this.column = column;
@@ -100,6 +121,11 @@ public Builder<T> withAlias(String alias) {
             return this;
         }
 
+        public Builder<T> withDescendingPhrase(String descendingPhrase) {
+            this.descendingPhrase = descendingPhrase;
+            return this;
+        }
+
         public SimpleCaseModel<T> build() {
             return new SimpleCaseModel<>(this);
         }

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

@@ -48,7 +48,9 @@ public FragmentAndParameters render() {
     }
 
     private FragmentAndParameters renderCase() {
-        return simpleCaseModel.column().render(renderingContext)
+        return simpleCaseModel.column().alias()
+                .map(FragmentAndParameters::fromFragment)
+                .orElseGet(() -> simpleCaseModel.column().render(renderingContext))
                 .mapFragment(f -> "case " + f); //$NON-NLS-1$
     }
 

src/main/java/org/mybatis/dynamic/sql/where/render/ColumnAndConditionRenderer.java

@@ -36,7 +36,9 @@ private ColumnAndConditionRenderer(Builder<T> builder) {
     }
 
     public FragmentAndParameters render() {
-        FragmentAndParameters renderedLeftColumn = column.render(renderingContext);
+        FragmentAndParameters renderedLeftColumn = column.alias()
+                .map(FragmentAndParameters::fromFragment)
+                .orElseGet(() -> column.render(renderingContext));
 
         DefaultConditionVisitor<T> visitor = DefaultConditionVisitor.withColumn(column)
                 .withRenderingContext(renderingContext)

src/test/java/examples/mariadb/NumbersDynamicSQLSupport.java

@@ -0,0 +1,36 @@
+/*
+ *    Copyright 2016-2024 the original author or authors.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package examples.mariadb;
+
+import org.mybatis.dynamic.sql.SqlColumn;
+import org.mybatis.dynamic.sql.SqlTable;
+
+import java.sql.JDBCType;
+
+public final class NumbersDynamicSQLSupport {
+    public static final Numbers numbers = new Numbers();
+    public static final SqlColumn<Integer> id = numbers.id;
+    public static final SqlColumn<String> description = numbers.description;
+
+    public static final class Numbers extends SqlTable {
+        public final SqlColumn<Integer> id = column("id", JDBCType.INTEGER);
+        public final SqlColumn<String> description = column("description", JDBCType.VARCHAR);
+
+        public Numbers() {
+            super("numbers");
+        }
+    }
+}