kotlin.jdbc.ResultSets.kt Maven / Gradle / Ivy

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package kotlin.jdbc

import java.sql.*

// Workaround for an import clash
import kotlin.Array

/**
 * Executes the specfied block with result set and then closes it
 */
public fun  ResultSet.use(block : (ResultSet) -> R) : R {
    try {
        return block(this)
    } finally {
        this.close()
    }
}

/**
* Creates an iterator through a [[ResultSet]]
*/
fun ResultSet.iterator() : Iterator {
    val rs = this
    return object : Iterator{
        public override fun hasNext() : Boolean = rs.next()

        public override fun next() : ResultSet = rs
    }
}

/**
 * Returns iterable that calls to the specified mapper function for each row
 */
fun  ResultSet.map(fn : (ResultSet) -> T) : Iterable {
    val rs = this

    val iterator = object : Iterator{
        public override fun hasNext() : Boolean = rs.next()

        public override fun next() : T = fn(rs)
    }

    return object : Iterable {
        public override fun iterator(): Iterator = iterator
    }
}

/**
 * Returns array with column names
 */
fun ResultSet.getColumnNames() : Array {
    val meta = getMetaData()
    return Array(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 : Array = getColumnNames()) : Array {
    return Array(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 : Array = getColumnNames()) : Map {
    val result = java.util.HashMap(columnNames.size())

    columnNames.forEach {
        result[it] = this[it]
    }

    return result
}

/**
 * Returns the value at the given column index (starting at 1)
 */
fun ResultSet.get(columnId: Int): Any? = this.getObject(columnId)

/**
 * Returns the value at the given column name
 */
fun ResultSet.get(columnName: String): Any? = this.getObject(columnName)

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)