Support for basic union queries in Kotlin

Author: jeffgbutler

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinBaseBuilders.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 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.

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinCountBuilder.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 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.

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinDeleteBuilder.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 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.

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinQueryBuilder.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 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.
@@ -50,6 +50,11 @@ class KotlinQueryBuilder(private val dsl: QueryExpressionDSL<SelectModel>) :
 
     fun allRows() = this
 
+    fun union(union: KotlinUnionBuilder.() -> QueryExpressionDSL<SelectModel>) =
+        apply {
+            union(KotlinUnionBuilder(dsl))
+        }
+
     override fun build(): SelectModel = dsl.build()
 
     override fun getWhere(): QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder = dsl.where()

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinUnionBuilders.kt

@@ -0,0 +1,51 @@
+/**
+ *    Copyright 2016-2020 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
+ *
+ *       http://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 org.mybatis.dynamic.sql.util.kotlin
+
+import org.mybatis.dynamic.sql.BasicColumn
+import org.mybatis.dynamic.sql.SqlTable
+import org.mybatis.dynamic.sql.select.QueryExpressionDSL
+import org.mybatis.dynamic.sql.select.SelectModel
+
+class KotlinUnionBuilder(private val dsl: QueryExpressionDSL<SelectModel>) {
+    fun select(vararg selectList: BasicColumn) =
+        select(listOf(*selectList))
+
+    fun select(selectList: List<BasicColumn>) =
+        KotlinUnionFromGatherer(dsl, selectList)
+}
+
+class KotlinUnionFromGatherer(
+    private val dsl: QueryExpressionDSL<SelectModel>,
+    private val selectList: List<BasicColumn>
+) {
+    fun from(
+        table: SqlTable,
+        enhance: KotlinUnionQueryBuilder.() -> KotlinUnionQueryBuilder
+    ): QueryExpressionDSL<SelectModel> {
+        val unionBuilder = KotlinUnionQueryBuilder(dsl.union().select(selectList).from(table))
+        enhance(unionBuilder)
+        return dsl
+    }
+}
+
+class KotlinUnionQueryBuilder(private val dsl: QueryExpressionDSL<SelectModel>) :
+    KotlinBaseJoiningBuilder<QueryExpressionDSL<SelectModel>, QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder,
+            KotlinUnionQueryBuilder>(dsl) {
+    override fun self() = this
+
+    override fun getWhere(): QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder = dsl.where()
+}

src/test/kotlin/examples/kotlin/spring/canonical/CanonicalSpringKotlinTest.kt

@@ -360,6 +360,69 @@ class CanonicalSpringKotlinTest {
         }
     }
 
+    @Test
+    fun testRawSelectWithUnion() {
+        val selectStatement = select(
+            id.`as`("A_ID"), firstName, lastName, birthDate, employed, occupation,
+            addressId
+        ).from(Person) {
+            where(id, isEqualTo(1))
+            union {
+                select(
+                    id.`as`("A_ID"), firstName, lastName, birthDate, employed, occupation,
+                    addressId
+                ).from(Person) {
+                    where(id, isEqualTo(2))
+                }
+            }
+            union {
+                select(
+                    id.`as`("A_ID"), firstName, lastName, birthDate, employed, occupation,
+                    addressId
+                ).from(Person) {
+                    where(id, isEqualTo(3))
+                }
+            }
+        }
+
+        val expected = "select id as A_ID, first_name, last_name, birth_date, employed, occupation, address_id " +
+            "from Person " +
+            "where id = :p1 " +
+            "union " +
+            "select id as A_ID, first_name, last_name, birth_date, employed, occupation, address_id " +
+            "from Person " +
+            "where id = :p2 " +
+            "union " +
+            "select id as A_ID, first_name, last_name, birth_date, employed, occupation, address_id " +
+            "from Person " +
+            "where id = :p3"
+
+        assertThat(selectStatement.selectStatement).isEqualTo(expected)
+
+        val records = template.selectList(selectStatement) { rs, _ ->
+            val record = PersonRecord()
+            record.id = rs.getInt(1)
+            record.firstName = rs.getString(2)
+            record.lastName = rs.getString(3)
+            record.birthDate = rs.getTimestamp(4)
+            record.employed = rs.getString(5)
+            record.occupation = rs.getString(6)
+            record.addressId = rs.getInt(7)
+            record
+        }
+
+        assertThat(records).hasSize(3)
+        with(records[0]!!) {
+            assertThat(id).isEqualTo(1)
+            assertThat(firstName).isEqualTo("Fred")
+            assertThat(lastName).isEqualTo("Flintstone")
+            assertThat(birthDate).isNotNull()
+            assertThat(employed).isEqualTo("Yes")
+            assertThat(occupation).isEqualTo("Brontosaurus Operator")
+            assertThat(addressId).isEqualTo(1)
+        }
+    }
+
     @Test
     fun testRawSelectWithJoin() {
         val selectStatement = select(