feat: add value_as_string to min/max aggregations

min/max aggregations return also value_as_string, which can be useful when
running over date fields:

{
  "aggregations": {
    "max-example": {
      "value": 1770336000000,
      "value_as_string": "2026-02-06"
    },
    "min-example": {
      "value": 1716422400000,
      "value_as_string": "2024-05-23"
    }
  }
}

It is possible to access them now.

elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/searches/aggs/responses/aggresponses.scala

@@ -78,14 +78,14 @@ object SignificantTermsAggResult {
   )
 }
 
-case class AvgAggResult(name: String, valueOpt: Option[Double]) extends MetricAggregation {
+case class AvgAggResult(name: String, valueOpt: Option[Double], valueAsString: Option[String]) extends MetricAggregation {
   def value: Double = valueOpt.get
 }
-case class SumAggResult(name: String, valueOpt: Option[Double]) extends MetricAggregation {
+case class SumAggResult(name: String, valueOpt: Option[Double], valueAsString: Option[String]) extends MetricAggregation {
   def value: Double = valueOpt.get
 }
-case class MinAggResult(name: String, value: Option[Double]) extends MetricAggregation
-case class MaxAggResult(name: String, value: Option[Double]) extends MetricAggregation
+case class MinAggResult(name: String, value: Option[Double], valueAsString: Option[String]) extends MetricAggregation
+case class MaxAggResult(name: String, value: Option[Double], valueAsString: Option[String]) extends MetricAggregation
 case class ValueCountResult(name: String, valueOpt: Option[Double]) extends MetricAggregation {
   def value: Double = valueOpt.get
 }
@@ -241,7 +241,7 @@ trait HasAggregations extends AggResult with Transformable {
   def significantTerms(name: String): SignificantTermsAggResult = SignificantTermsAggResult(name, agg(name))
 
   // metric aggs
-  def avg(name: String): AvgAggResult = AvgAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble))
+  def avg(name: String): AvgAggResult = AvgAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble), agg(name).get("value_as_string").map(_.toString))
 
   def extendedStats(name: String): ExtendedStatsAggResult =
     ExtendedStatsAggResult(
@@ -257,9 +257,9 @@ trait HasAggregations extends AggResult with Transformable {
     )
 
   def cardinality(name: String): CardinalityAggResult = CardinalityAggResult(name, agg(name)("value").toString.toDouble)
-  def sum(name: String): SumAggResult = SumAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble))
-  def min(name: String): MinAggResult = MinAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble))
-  def max(name: String): MaxAggResult = MaxAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble))
+  def sum(name: String): SumAggResult = SumAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble), agg(name).get("value_as_string").map(_.toString))
+  def min(name: String): MinAggResult = MinAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble), agg(name).get("value_as_string").map(_.toString))
+  def max(name: String): MaxAggResult = MaxAggResult(name, Option(agg(name)("value")).map(_.toString.toDouble), agg(name).get("value_as_string").map(_.toString))
 
   def percentiles(name: String): PercentilesAggResult = {
     // can be keyed, so values can be either map or list

elastic4s-tests/src/test/scala/com/sksamuel/elastic4s/requests/searches/aggs/MinMaxAggregationHttpTest.scala

@@ -25,7 +25,8 @@ class MinMaxAggregationHttpTest extends AnyFreeSpec with DockerTests with Matche
     createIndex("minmaxagg") mapping {
       properties(
         textField("name").fielddata(true),
-        intField("height").stored(true)
+        intField("height").stored(true),
+        dateField("opened").format("strict_date")
       )
     }
   }.await
@@ -50,23 +51,25 @@ class MinMaxAggregationHttpTest extends AnyFreeSpec with DockerTests with Matche
 
   client.execute(
     bulk(
-      indexInto("minmaxagg") fields("name" -> "Willis Tower", "height" -> 1244),
-      indexInto("minmaxagg") fields("name" -> "Burj Kalifa", "height" -> 2456),
-      indexInto("minmaxagg") fields("name" -> "Tower of London", "height" -> 169),
+      indexInto("minmaxagg") fields("name" -> "Willis Tower", "height" -> 1244, "opened" -> "1973-09-01"),
+      indexInto("minmaxagg") fields("name" -> "Burj Kalifa", "height" -> 2456, "opened" -> "2010-01-04"),
+      indexInto("minmaxagg") fields("name" -> "Tower of London", "height" -> 169, "opened" -> "1285-01-01"),
       indexInto("minmaxagg2") fields ("name" -> "building of unknown height")
     ).refresh(RefreshPolicy.Immediate)
   ).await
 
   "max agg" - {
     "should return the max for the context" in {
       val resp = client.execute {
-        search("minmaxagg").matchAllQuery().aggs {
-          maxAgg("agg1", "height")
-        }
+        search("minmaxagg").matchAllQuery().aggs(
+          maxAgg("agg1", "height"),
+          maxAgg("opened", "opened"),
+        )
       }.await.result
       resp.totalHits shouldBe 3
       val agg = resp.aggs.max("agg1")
       agg.value shouldBe Some(2456)
+      resp.aggs.max("opened").valueAsString shouldBe Some("2010-01-04")
     }
     "should support results when matching docs do not define the field" in {
       val resp = client.execute {
@@ -93,13 +96,15 @@ class MinMaxAggregationHttpTest extends AnyFreeSpec with DockerTests with Matche
   "min agg" - {
     "should return the max for the context" in {
       val resp = client.execute {
-        search("minmaxagg").matchAllQuery().aggs {
-          minAgg("agg1", "height")
-        }
+        search("minmaxagg").matchAllQuery().aggs(
+          minAgg("agg1", "height"),
+          minAgg("opened", "opened")
+        )
       }.await.result
       resp.totalHits shouldBe 3
       val agg = resp.aggs.min("agg1")
       agg.value shouldBe Some(169)
+      resp.aggs.min("opened").valueAsString shouldBe Some("1285-01-01")
     }
     "should support results matching docs do not define the field" in {
       val resp = client.execute {