Add a cast for doubles

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/SqlBuilder.java

@@ -535,6 +535,10 @@ static CastFinisher cast(String value) {
         return cast(stringConstant(value));
     }
 
+    static CastFinisher cast(Double value) {
+        return cast(constant(value.toString()));
+    }
+
     static CastFinisher cast(BasicColumn column) {
         return new CastFinisher(column);
     }

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/elements/CastDSL.kt

@@ -31,6 +31,10 @@ class CastDSL {
         cast = SqlBuilder.cast(this).`as`(targetType)
     }
 
+    infix fun Double.`as`(targetType: String) {
+        cast = SqlBuilder.cast(this).`as`(targetType)
+    }
+
     infix fun BasicColumn.`as`(targetType: String) {
         cast = SqlBuilder.cast(this).`as`(targetType)
     }

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

@@ -59,5 +59,5 @@ ERROR.39=When clauses in case expressions must render (optional conditions are n
 ERROR.40=Case expressions must have at least one "when" clause
 ERROR.41=You cannot call "then" in a Kotlin case expression more than once
 ERROR.42=You cannot call `else` in a Kotlin case expression more than once
-ERROR.43=A Kotlin cast expression must have one, and only one, cast 
+ERROR.43=A Kotlin cast expression must have one, and only one, `as` element
 INTERNAL.ERROR=Internal Error {0}

src/test/kotlin/examples/kotlin/animal/data/KCaseExpressionTest.kt

@@ -840,6 +840,49 @@ class KCaseExpressionTest {
         }
     }
 
+    @Test
+    fun testCaseCastDoubles() {
+        newSession().use { session ->
+            val mapper = session.getMapper(CommonSelectMapper::class.java)
+
+            val selectStatement = select(
+                animalName,
+                case(animalName) {
+                    `when`(isEqualTo("Artic fox"), isEqualTo("Red fox")) { then( 1.1) }
+                    `else`(cast { 2.2 `as` "DOUBLE" })
+                }.`as`("IsAFox")
+            ) {
+                from(animalData)
+                where { id.isIn(31, 32, 38, 39) }
+                orderBy(id)
+            }
+
+            val expected = "select animal_name, " +
+                    "case animal_name when = #{parameters.p1,jdbcType=VARCHAR}, = #{parameters.p2,jdbcType=VARCHAR} then 1.1 " +
+                    "else cast(2.2 as DOUBLE) end " +
+                    "as IsAFox from AnimalData where id in " +
+                    "(#{parameters.p3,jdbcType=INTEGER},#{parameters.p4,jdbcType=INTEGER},#{parameters.p5,jdbcType=INTEGER},#{parameters.p6,jdbcType=INTEGER}) " +
+                    "order by id"
+            assertThat(selectStatement.selectStatement).isEqualTo(expected)
+            assertThat(selectStatement.parameters)
+                .containsOnly(
+                    entry("p1", "Artic fox"),
+                    entry("p2", "Red fox"),
+                    entry("p3", 31),
+                    entry("p4", 32),
+                    entry("p5", 38),
+                    entry("p6", 39)
+                )
+
+            val records = mapper.selectManyMappedRows(selectStatement)
+            assertThat(records).hasSize(4)
+            assertThat(records[0]).containsOnly(entry("ANIMAL_NAME", "Cat"), entry("ISAFOX", 2.2))
+            assertThat(records[1]).containsOnly(entry("ANIMAL_NAME", "Artic fox"), entry("ISAFOX", 1.1))
+            assertThat(records[2]).containsOnly(entry("ANIMAL_NAME", "Red fox"), entry("ISAFOX", 1.1))
+            assertThat(records[3]).containsOnly(entry("ANIMAL_NAME", "Raccoon"), entry("ISAFOX", 2.2))
+        }
+    }
+
     @Test
     fun testInvalidDoubleElseSimple() {
         assertThatExceptionOfType(KInvalidSQLException::class.java).isThrownBy {