[LIVY-1083] Coerce batch/session Int fields sent as JSON strings

server/src/main/scala/org/apache/livy/server/batch/CreateBatchRequest.scala

@@ -17,6 +17,8 @@
 
 package org.apache.livy.server.batch
 
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize
+
 class CreateBatchRequest {
 
   var file: String = _
@@ -27,9 +29,13 @@ class CreateBatchRequest {
   var pyFiles: List[String] = List()
   var files: List[String] = List()
   var driverMemory: Option[String] = None
+  // contentAs pins the element type past erasure so Jackson coerces numeric strings (e.g. "4").
+  @JsonDeserialize(contentAs = classOf[java.lang.Integer])
   var driverCores: Option[Int] = None
   var executorMemory: Option[String] = None
+  @JsonDeserialize(contentAs = classOf[java.lang.Integer])
   var executorCores: Option[Int] = None
+  @JsonDeserialize(contentAs = classOf[java.lang.Integer])
   var numExecutors: Option[Int] = None
   var archives: List[String] = List()
   var queue: Option[String] = None

server/src/main/scala/org/apache/livy/server/interactive/CreateInteractiveRequest.scala

@@ -17,6 +17,8 @@
 
 package org.apache.livy.server.interactive
 
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize
+
 import org.apache.livy.sessions.{Kind, Shared}
 
 class CreateInteractiveRequest {
@@ -26,9 +28,13 @@ class CreateInteractiveRequest {
   var pyFiles: List[String] = List()
   var files: List[String] = List()
   var driverMemory: Option[String] = None
+  // contentAs pins the element type past erasure so Jackson coerces numeric strings (e.g. "4").
+  @JsonDeserialize(contentAs = classOf[java.lang.Integer])
   var driverCores: Option[Int] = None
   var executorMemory: Option[String] = None
+  @JsonDeserialize(contentAs = classOf[java.lang.Integer])
   var executorCores: Option[Int] = None
+  @JsonDeserialize(contentAs = classOf[java.lang.Integer])
   var numExecutors: Option[Int] = None
   var archives: List[String] = List()
   var queue: Option[String] = None

server/src/test/scala/org/apache/livy/server/batch/CreateBatchRequestSpec.scala

@@ -50,6 +50,59 @@ class CreateBatchRequestSpec extends AnyFunSpec with LivyBaseUnitTestSuite {
       assert(req.conf === Map())
     }
 
+    it("should deserialize numeric fields sent as JSON numbers") {
+      val json =
+        """{ "file" : "foo", "driverCores" : 4, "executorCores" : 2, "numExecutors" : 20 }"""
+      val req = mapper.readValue(json, classOf[CreateBatchRequest])
+      assert(req.driverCores === Some(4))
+      assert(req.executorCores === Some(2))
+      assert(req.numExecutors === Some(20))
+    }
+
+    it("should coerce numeric fields sent as JSON strings") {
+      // A mistyped client that sends "4" instead of 4 must not blow up with a
+      // ClassCastException in BatchSession.createSparkApp -- Jackson coerces the string.
+      val json =
+        """{ "file" : "foo", "driverCores" : "4", "executorCores" : "2", "numExecutors" : "20" }"""
+      val req = mapper.readValue(json, classOf[CreateBatchRequest])
+      assert(req.driverCores === Some(4))
+      assert(req.executorCores === Some(2))
+      assert(req.numExecutors === Some(20))
+      // The unbox that used to throw at BatchSession.scala:95 now succeeds.
+      assert(req.driverCores.map(_ + 1) === Some(5))
+    }
+
+    it("should reject a non-numeric string for a numeric field with a mapping error") {
+      val json = """{ "file" : "foo", "driverCores" : "notanumber" }"""
+      intercept[JsonMappingException] {
+        mapper.readValue(json, classOf[CreateBatchRequest])
+      }
+    }
+
+    it("should treat an empty string as None") {
+      // Jackson's scalar coercion maps "" → null, which Option deserializes as None.
+      val req = mapper.readValue("""{ "file" : "foo", "driverCores" : "" }""",
+        classOf[CreateBatchRequest])
+      assert(req.driverCores === None)
+    }
+
+    it("should coerce whitespace-padded numeric strings") {
+      val req = mapper.readValue(
+        """{ "file" : "foo", "driverCores" : "4 ", "executorCores" : " 2" }""",
+        classOf[CreateBatchRequest])
+      assert(req.driverCores === Some(4))
+      assert(req.executorCores === Some(2))
+    }
+
+    it("should reject fractional numeric strings with a mapping error") {
+      Seq("""{ "file" : "foo", "driverCores" : "4.5" }""",
+          """{ "file" : "foo", "driverCores" : "4.0" }""").foreach { json =>
+        intercept[JsonMappingException] {
+          mapper.readValue(json, classOf[CreateBatchRequest])
+        }
+      }
+    }
+
   }
 
 }

server/src/test/scala/org/apache/livy/server/interactive/CreateInteractiveRequestSpec.scala

@@ -17,7 +17,7 @@
 
 package org.apache.livy.server.interactive
 
-import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.databind.{JsonMappingException, ObjectMapper}
 import org.scalatest.funspec.AnyFunSpec
 
 import org.apache.livy.LivyBaseUnitTestSuite
@@ -50,6 +50,58 @@ class CreateInteractiveRequestSpec extends AnyFunSpec with LivyBaseUnitTestSuite
       assert(req.conf === Map())
     }
 
+    it("should deserialize numeric fields sent as JSON numbers") {
+      val json =
+        """{ "kind" : "pyspark", "driverCores" : 4, "executorCores" : 2, "numExecutors" : 20 }"""
+      val req = mapper.readValue(json, classOf[CreateInteractiveRequest])
+      assert(req.driverCores === Some(4))
+      assert(req.executorCores === Some(2))
+      assert(req.numExecutors === Some(20))
+    }
+
+    it("should coerce numeric fields sent as JSON strings") {
+      // Same Option[Int] erasure fix as CreateBatchRequest — string "4" must coerce to 4.
+      val json =
+        """{ "kind" : "pyspark", "driverCores" : "4", "executorCores" : "2", """ +
+          """"numExecutors" : "20" }"""
+      val req = mapper.readValue(json, classOf[CreateInteractiveRequest])
+      assert(req.driverCores === Some(4))
+      assert(req.executorCores === Some(2))
+      assert(req.numExecutors === Some(20))
+      assert(req.driverCores.map(_ + 1) === Some(5))
+    }
+
+    it("should reject a non-numeric string for a numeric field with a mapping error") {
+      val json = """{ "kind" : "pyspark", "driverCores" : "notanumber" }"""
+      intercept[JsonMappingException] {
+        mapper.readValue(json, classOf[CreateInteractiveRequest])
+      }
+    }
+
+    it("should treat an empty string as None") {
+      // Jackson's scalar coercion maps "" → null, which Option deserializes as None.
+      val req = mapper.readValue("""{ "kind" : "pyspark", "driverCores" : "" }""",
+        classOf[CreateInteractiveRequest])
+      assert(req.driverCores === None)
+    }
+
+    it("should coerce whitespace-padded numeric strings") {
+      val req = mapper.readValue(
+        """{ "kind" : "pyspark", "driverCores" : "4 ", "executorCores" : " 2" }""",
+        classOf[CreateInteractiveRequest])
+      assert(req.driverCores === Some(4))
+      assert(req.executorCores === Some(2))
+    }
+
+    it("should reject fractional numeric strings with a mapping error") {
+      Seq("""{ "kind" : "pyspark", "driverCores" : "4.5" }""",
+          """{ "kind" : "pyspark", "driverCores" : "4.0" }""").foreach { json =>
+        intercept[JsonMappingException] {
+          mapper.readValue(json, classOf[CreateInteractiveRequest])
+        }
+      }
+    }
+
   }
 
 }