SecondaryIndex

Filter the results of scan or query within DynamoDB

Note that rows filtered out still count towards your consumed capacity

>>> case class Transport(mode: String, line: String, colour: String)
>>> val transport = Table[Transport]("transport")

>>> val client = LocalDynamoDB.client()
>>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
>>> import com.gu.scanamo.syntax._

>>> LocalDynamoDB.withTableWithSecondaryIndex(client)("transport", "colour-index")(
...   'mode -> S, 'line -> S)('mode -> S, 'colour -> S
... ) {
...   val operations = for {
...     _ <- transport.putAll(Set(
...       Transport("Underground", "Circle", "Yellow"),
...       Transport("Underground", "Metropolitan", "Magenta"),
...       Transport("Underground", "Central", "Red"),
...       Transport("Underground", "Picadilly", "Blue"),
...       Transport("Underground", "Northern", "Black")))
...     somethingBeginningWithC <- transport.index("colour-index")
...                                   .filter('line beginsWith ("C"))
...                                   .query('mode -> "Underground")
...   } yield somethingBeginningWithC.toList
...   Scanamo.exec(client)(operations)
... }
List(Right(Transport(Underground,Central,Red)), Right(Transport(Underground,Circle,Yellow)))

Query or scan an index, limiting the number of items evaluated by Dynamo

>>> case class Transport(mode: String, line: String, colour: String)
>>> val transport = Table[Transport]("transport")

>>> val client = LocalDynamoDB.client()
>>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
>>> import com.gu.scanamo.syntax._

>>> LocalDynamoDB.withTableWithSecondaryIndex(client)("transport", "colour-index")(
...   'mode -> S, 'line -> S)('mode -> S, 'colour -> S
... ) {
...   val operations = for {
...     _ <- transport.putAll(Set(
...       Transport("Underground", "Circle", "Yellow"),
...       Transport("Underground", "Metropolitan", "Magenta"),
...       Transport("Underground", "Central", "Red"),
...       Transport("Underground", "Picadilly", "Blue"),
...       Transport("Underground", "Northern", "Black")))
...     somethingBeginningWithBl <- transport.index("colour-index").limit(1).query(
...       ('mode -> "Underground" and ('colour beginsWith "Bl")).descending
...     )
...   } yield somethingBeginningWithBl.toList
...   Scanamo.exec(client)(operations)
... }
List(Right(Transport(Underground,Picadilly,Blue)))

Run a query against keys in a secondary index

>>> case class GithubProject(organisation: String, repository: String, language: String, license: String)
>>> val githubProjects = Table[GithubProject]("github-projects")

>>> val client = LocalDynamoDB.client()
>>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._

>>> import com.gu.scanamo.syntax._

>>> LocalDynamoDB.withTableWithSecondaryIndex(client)("github-projects", "language-license")('organisation -> S, 'repository -> S)('language -> S, 'license -> S) {
...   val operations = for {
...     _ <- githubProjects.putAll(Set(
...       GithubProject("typelevel", "cats", "Scala", "MIT"),
...       GithubProject("localytics", "sbt-dynamodb", "Scala", "MIT"),
...       GithubProject("tpolecat", "tut", "Scala", "MIT"),
...       GithubProject("guardian", "scanamo", "Scala", "Apache 2")
...     ))
...     scalaMIT <- githubProjects.index("language-license").query('language -> "Scala" and ('license -> "MIT"))
...   } yield scalaMIT.toList
...   Scanamo.exec(client)(operations)
... }
List(Right(GithubProject(typelevel,cats,Scala,MIT)), Right(GithubProject(tpolecat,tut,Scala,MIT)), Right(GithubProject(localytics,sbt-dynamodb,Scala,MIT)))

Scan a secondary index

This will only return items with a value present in the secondary index

>>> case class Bear(name: String, favouriteFood: String, antagonist: Option[String])

>>> val client = LocalDynamoDB.client()
>>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
>>> val table = Table[Bear]("bears")

>>> import com.gu.scanamo.syntax._

>>> LocalDynamoDB.withTableWithSecondaryIndex(client)("bears", "antagonist")('name -> S)('antagonist -> S) {
...   val ops = for {
...     _ <- table.put(Bear("Pooh", "honey", None))
...     _ <- table.put(Bear("Yogi", "picnic baskets", Some("Ranger Smith")))
...     _ <- table.put(Bear("Paddington", "marmalade sandwiches", Some("Mr Curry")))
...     antagonisticBears <- table.index("antagonist").scan()
...   } yield antagonisticBears
...   Scanamo.exec(client)(ops)
... }
List(Right(Bear(Paddington,marmalade sandwiches,Some(Mr Curry))), Right(Bear(Yogi,picnic baskets,Some(Ranger Smith))))