Additional methods to extract data from ResultSet and to create new connection with no DataSource

libraries/kotlin-jdbc/src/main/kotlin/kotlin/jdbc/Connections.kt

@@ -3,9 +3,47 @@ package kotlin.jdbc
 import java.sql.*
 import kotlin.template.StringTemplate
 import java.math.BigDecimal
+import java.util.Map
+import java.util.Properties
+
+private fun Map<String, String>.toProperties() : Properties {
+    val p = Properties()
+
+    this.keySet().forEach {
+        p.put(it, this[it])
+    }
+
+    return p
+}
 
 /**
- * Helper method to process a statement on this collection
+ * create connection for the specified jdbc url with no credentials
+ */
+fun getConnection(url : String) : Connection = DriverManager.getConnection(url).sure()
+
+/**
+ * create connection for the specified jdbc url and properties
+ */
+fun getConnection(url : String, info : Map<String, String>) : Connection = DriverManager.getConnection(url, info.toProperties())!!
+
+/**
+ * create connection for the specified jdbc url and credentials
+ */
+fun getConnection(url : String, user : String, password : String) : Connection = DriverManager.getConnection(url, user, password)!!
+
+/**
+ * Executes specified block with connection and close connection after this
+ */
+fun Connection.use(block : (Connection) -> Any?) : Unit {
+    try {
+        block(this)
+    } finally {
+        this.close()
+    }
+}
+
+/**
+ * Helper method to process a statement on this connection
  */
 fun <T> Connection.statement(block: (Statement) -> T): T {
     val statement = createStatement()

libraries/kotlin-jdbc/src/main/kotlin/kotlin/jdbc/ResultSets.kt

@@ -4,6 +4,18 @@ import java.sql.*
 import java.util.ArrayList
 import java.util.Collection
 import java.util.List
+import java.util.Map
+
+/**
+ * Executes the specfied block with result set and then closes it
+ */
+public fun <R> ResultSet.use(block : (ResultSet) -> R) : R {
+    try {
+        return block(this)
+    } finally {
+        this.close()
+    }
+}
 
 /**
 * Creates an iterator through a [[ResultSet]]
@@ -18,6 +30,56 @@ fun ResultSet.iterator() : Iterator<ResultSet> {
     }
 }
 
+/**
+ * Returns iterable that calls to the specified mapper function for each row
+ */
+fun <T> ResultSet.getMapped(fn : (ResultSet) -> T) : jet.Iterable<T> {
+    val rs = this
+
+    val iterator = object : Iterator<T>{
+        public override val hasNext : Boolean
+            get() = rs.next()
+
+        public override fun next() : T = fn(rs)
+    }
+
+    return object : jet.Iterable<T> {
+        public override fun iterator(): Iterator<T> = iterator
+    }
+}
+
+/**
+ * Returns array with column names
+ */
+fun ResultSet.getColumnNames() : jet.Array<String> {
+    val meta = getMetaData().sure()
+    return jet.Array<String>(meta.getColumnCount(), {meta.getColumnName(it + 1) ?: it.toString()})
+}
+
+/**
+ * Return array filled with values from current row in the cursor. Values will have the same order as column's order
+ * @columnNames you can specify column names to extract otherwise all columns will be extracted
+ */
+fun ResultSet.getValues(columnNames : jet.Array<String> = getColumnNames()) : jet.Array<Any?> {
+    return jet.Array<Any?>(columnNames.size, {
+        this[columnNames[it]]
+    })
+}
+
+/**
+ * Return map filled with values from current row in the cursor. Uses column names as keys for result map.
+ * @param columnNames you can specify column names to extract otherwise all columns will be extracted
+ */
+fun ResultSet.getValuesAsMap(columnNames : jet.Array<String> = getColumnNames()) : java.util.Map<String, Any?> {
+    val result = java.util.HashMap<String, Any?>(columnNames.size)
+
+    columnNames.forEach {
+        result[it] = this[it]
+    }
+
+    return result
+}
+
 /**
  * Returns the value at the given column index (starting at 1)
  */
@@ -47,3 +109,26 @@ fun <T> ResultSet.mapTo(result: Collection<T>, fn: (ResultSet) -> T) : Collectio
     }
     return result
 }
+
+private fun ResultSet.ensureHasRow() : ResultSet {
+    if (!next()) {
+        throw IllegalStateException("There are no rows left in cursor")
+    }
+    return this
+}
+
+/**
+ * Returns int value from the cursor at first column. May be useful to get result of count(*)
+ */
+fun ResultSet.singleInt() : Int = ensureHasRow().getInt(1)
+
+/**
+ * Returns long value from the cursor at first column.
+ */
+fun ResultSet.singleLong() : Long = ensureHasRow().getLong(1)
+
+/**
+ * Returns double value from the cursor at first column.
+ */
+fun ResultSet.singleDouble() : Double = ensureHasRow().getDouble(1)
+

libraries/kotlin-jdbc/src/test/kotlin/test/kotlin/jdbc/JdbcTest.kt

@@ -7,6 +7,8 @@ import junit.framework.TestCase
 import org.h2.jdbcx.JdbcDataSource
 import javax.sql.DataSource
 import org.h2.jdbcx.JdbcConnectionPool
+import kotlin.nullable.forEach
+import java.sql.ResultSet
 
 public val dataSource : DataSource = createDataSource()
 
@@ -40,4 +42,48 @@ class JdbcTest : TestCase() {
             }
         }
     }
+
+    fun testGetValuesAsMap() {
+        dataSource.query("select * from foo") {
+            for (row in it) {
+                println(row.getValuesAsMap())
+            }
+        }
+    }
+
+    fun testStringFormat() {
+        dataSource.query(kotlin.template.StringTemplate(array("select * from foo where id = ", 1))) {
+            for (row in it) {
+                println(row.getValuesAsMap())
+            }
+        }
+    }
+
+    fun testMapIterator() {
+        val mapper = { (rs : ResultSet) ->
+            "id: ${rs["id"]}"
+        }
+
+        dataSource.query("select * from foo") {
+            for (row in it.getMapped(mapper)) {
+                println(row)
+            }
+        }
+    }
+
+    fun testCount() {
+        dataSource.query("select count(*) from foo") {
+            println("count: ${it.singleInt()}")
+        }
+    }
+
+    fun testFormatCursor() {
+        dataSource.query("select * from foo") {
+            println(it.getColumnNames().toList().makeString("\t"))
+
+            for (row in it) {
+                println(it.getValues().makeString("\t"))
+            }
+        }
+    }
 }