Merge pull request #6 from guardian/put-all

Add support for putting multiple items at at time

src/main/scala/com/gu/scanamo/Scanamo.scala

@@ -33,6 +33,23 @@ object Scanamo {
   def put[T](client: AmazonDynamoDB)(tableName: String)(item: T)(implicit f: DynamoFormat[T]): PutItemResult =
     client.putItem(putRequest(tableName)(item))
 
+  /**
+    * {{{
+    * >>> val client = LocalDynamoDB.client()
+    * >>> case class Rabbit(name: String)
+    * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
+    * >>> val createTableResult = LocalDynamoDB.createTable(client)("rabbits")('name -> S)
+    * >>> val multiPut = Scanamo.putAll(client)("rabbits")((
+    * ...   for { _ <- 0 until 100 } yield Rabbit(util.Random.nextString(500))).toList).toList
+    * >>> Scanamo.scan[Rabbit](client)("rabbits").toList.size
+    * 100
+    * }}}
+    */
+  def putAll[T](client: AmazonDynamoDB)(tableName: String)(items: List[T])(implicit f: DynamoFormat[T]): Streaming[BatchWriteItemResult] =
+    Streaming.fromIteratorUnsafe(for {
+      batch <- items.grouped(25)
+    } yield client.batchWriteItem(batchPutRequest(tableName)(batch)))
+
   /**
     * {{{
     * >>> val client = LocalDynamoDB.client()

src/main/scala/com/gu/scanamo/ScanamoRequest.scala

@@ -20,6 +20,10 @@ object ScanamoRequest {
   def putRequest[T](tableName: String)(item: T)(implicit f: DynamoFormat[T]): PutItemRequest =
     new PutItemRequest().withTableName(tableName).withItem(f.write(item).getM)
 
+  def batchPutRequest[T](tableName: String)(items: List[T])(implicit f: DynamoFormat[T]): BatchWriteItemRequest =
+    new BatchWriteItemRequest().withRequestItems(Map(tableName -> items.map(i =>
+      new WriteRequest().withPutRequest(new PutRequest().withItem(f.write(i).getM))
+    ).asJava).asJava)
 
   /**
     * {{{