combine conditions

Author: vincentlauvlwj

ktorm-core/src/main/kotlin/me/liuwj/ktorm/dsl/Query.kt

@@ -3,10 +3,7 @@ package me.liuwj.ktorm.dsl
 import me.liuwj.ktorm.database.Database
 import me.liuwj.ktorm.database.prepareStatement
 import me.liuwj.ktorm.expression.*
-import me.liuwj.ktorm.schema.ColumnDeclaring
-import me.liuwj.ktorm.schema.DoubleSqlType
-import me.liuwj.ktorm.schema.IntSqlType
-import me.liuwj.ktorm.schema.Table
+import me.liuwj.ktorm.schema.*
 import java.sql.ResultSet
 import javax.sql.rowset.RowSetProvider
 
@@ -192,6 +189,14 @@ inline fun Query.whereWithOrConditions(block: (MutableList<ScalarExpression<Bool
     }
 }
 
+fun Iterable<ScalarExpression<Boolean>>.combineConditions(): ScalarExpression<Boolean> {
+    if (this.any()) {
+        return this.reduce { a, b -> a and b }
+    } else {
+        return ArgumentExpression(true, BooleanSqlType)
+    }
+}
+
 fun Query.groupBy(vararg columns: ColumnDeclaring<*>): Query {
     return this.withExpression { expr ->
         when (expr) {

ktorm-core/src/test/kotlin/me/liuwj/ktorm/dsl/QueryTest.kt

@@ -1,6 +1,7 @@
 package me.liuwj.ktorm.dsl
 
 import me.liuwj.ktorm.BaseTest
+import me.liuwj.ktorm.expression.ScalarExpression
 import org.junit.Test
 
 /**
@@ -57,6 +58,21 @@ class QueryTest : BaseTest() {
         assert(name == "vince")
     }
 
+    @Test
+    fun testCombineConditions() {
+        val t = Employees.aliased("t")
+
+        val names = t
+            .select(t.name)
+            .where { emptyList<ScalarExpression<Boolean>>().combineConditions() }
+            .orderBy(t.id.asc())
+            .map { it.getString(1) }
+
+        assert(names.size == 4)
+        assert(names[0] == "vince")
+        assert(names[1] == "marry")
+    }
+
     @Test
     fun testOrderBy() {
         val names = Employees