[Backport 2.x] add queryFieldNames field in Doc Level Queries

src/main/kotlin/org/opensearch/commons/alerting/model/DocLevelQuery.kt

@@ -16,7 +16,8 @@
     val name: String,
     val fields: List<String>,
     val query: String,
-    val tags: List<String> = mutableListOf()
+    val tags: List<String> = mutableListOf(),
+    val queryFieldNames: List<String> = mutableListOf()
 ) : BaseModel {
 
     init {
@@ -33,7 +34,8 @@
         sin.readString(), // name
         sin.readStringList(), // fields
         sin.readString(), // query
-        sin.readStringList() // tags
+        sin.readStringList(), // tags,
+        sin.readStringList() // fieldsBeingQueried
     )
 
     fun asTemplateArg(): Map<String, Any> {
@@ -42,7 +44,8 @@
             NAME_FIELD to name,
             FIELDS_FIELD to fields,
             QUERY_FIELD to query,
-            TAGS_FIELD to tags
+            TAGS_FIELD to tags,
+            QUERY_FIELD_NAMES_FIELD to queryFieldNames
         )
     }
 
@@ -53,6 +56,7 @@
         out.writeStringCollection(fields)
         out.writeString(query)
         out.writeStringCollection(tags)
+        out.writeStringCollection(queryFieldNames)
     }
 
     override fun toXContent(builder: XContentBuilder, params: ToXContent.Params): XContentBuilder {
@@ -62,6 +66,7 @@
             .field(FIELDS_FIELD, fields.toTypedArray())
             .field(QUERY_FIELD, query)
             .field(TAGS_FIELD, tags.toTypedArray())
+            .field(QUERY_FIELD_NAMES_FIELD, queryFieldNames.toTypedArray())
             .endObject()
         return builder
     }
@@ -72,6 +77,7 @@
         const val FIELDS_FIELD = "fields"
         const val QUERY_FIELD = "query"
         const val TAGS_FIELD = "tags"
+        const val QUERY_FIELD_NAMES_FIELD = "query_field_names"
         const val NO_ID = ""
         val INVALID_CHARACTERS: List<String> = listOf(" ", "[", "]", "{", "}", "(", ")")
 
@@ -83,6 +89,7 @@
             lateinit var name: String
             val tags: MutableList<String> = mutableListOf()
             val fields: MutableList<String> = mutableListOf()
+            val queryFieldNames: MutableList<String> = mutableListOf()
 
             XContentParserUtils.ensureExpectedToken(XContentParser.Token.START_OBJECT, xcp.currentToken(), xcp)
             while (xcp.nextToken() != XContentParser.Token.END_OBJECT) {
@@ -95,6 +102,7 @@
                         name = xcp.text()
                         validateQuery(name)
                     }
+
                     QUERY_FIELD -> query = xcp.text()
                     TAGS_FIELD -> {
                         XContentParserUtils.ensureExpectedToken(
@@ -108,6 +116,7 @@
                             tags.add(tag)
                         }
                     }
+
                     FIELDS_FIELD -> {
                         XContentParserUtils.ensureExpectedToken(
                             XContentParser.Token.START_ARRAY,
@@ -119,6 +128,18 @@
                             fields.add(field)
                         }
                     }
+
+                    QUERY_FIELD_NAMES_FIELD -> {
+                        XContentParserUtils.ensureExpectedToken(
+                            XContentParser.Token.START_ARRAY,
+                            xcp.currentToken(),
+                            xcp
+                        )
+                        while (xcp.nextToken() != XContentParser.Token.END_ARRAY) {
+                            val field = xcp.text()
+                            queryFieldNames.add(field)
+                        }
+                    }
                 }
             }
 
@@ -127,7 +148,8 @@
                 name = name,
                 fields = fields,
                 query = query,
-                tags = tags
+                tags = tags,
+                queryFieldNames = queryFieldNames
             )
         }
 
@@ -148,4 +170,20 @@
             }
         }
     }
+
+    // constructor for java plugins' convenience to optionally avoid passing empty list for 'fieldsBeingQueried' field
+    constructor(
+        id: String,
+        name: String,
+        fields: MutableList<String>,
+        query: String,
+        tags: MutableList<String>
+    ) : this(
+        id = id,
+        name = name,
+        fields = fields,
+        query = query,
+        tags = tags,
+        queryFieldNames = emptyList()
+    )
 }

src/test/kotlin/org/opensearch/commons/alerting/model/WriteableTests.kt

@@ -20,6 +20,7 @@ import org.opensearch.commons.alerting.randomUserEmpty
 import org.opensearch.commons.authuser.User
 import org.opensearch.core.common.io.stream.StreamInput
 import org.opensearch.search.builder.SearchSourceBuilder
+import kotlin.test.assertTrue
 
 class WriteableTests {
 
@@ -121,6 +122,19 @@ class WriteableTests {
         val sin = StreamInput.wrap(out.bytes().toBytesRef().bytes)
         val newDlq = DocLevelQuery.readFrom(sin)
         Assertions.assertEquals(dlq, newDlq, "Round tripping DocLevelQuery doesn't work")
+        assertTrue(newDlq.queryFieldNames.isEmpty())
+    }
+
+    @Test
+    fun `test doc-level query with query Field Names as stream`() {
+        val dlq = randomDocLevelQuery().copy(queryFieldNames = listOf("f1", "f2"))
+        val out = BytesStreamOutput()
+        dlq.writeTo(out)
+        val sin = StreamInput.wrap(out.bytes().toBytesRef().bytes)
+        val newDlq = DocLevelQuery.readFrom(sin)
+        assertTrue(newDlq.queryFieldNames.contains(dlq.queryFieldNames[0]))
+        assertTrue(newDlq.queryFieldNames.contains(dlq.queryFieldNames[1]))
+        Assertions.assertEquals(dlq, newDlq, "Round tripping DocLevelQuery doesn't work")
     }
 
     @Test

src/test/kotlin/org/opensearch/commons/alerting/model/XContentTests.kt

@@ -431,6 +431,18 @@ class XContentTests {
         )
     }
 
+    @Test
+    fun `test doc level query toXcontent with query field names`() {
+        val dlq = DocLevelQuery("id", "name", listOf("f1", "f2"), "query", listOf("t1", "t2"), listOf("f1", "f2"))
+        val dlqString = dlq.toXContent(builder(), ToXContent.EMPTY_PARAMS).string()
+        val parsedDlq = DocLevelQuery.parse(parser(dlqString))
+        Assertions.assertEquals(
+            dlq,
+            parsedDlq,
+            "Round tripping Doc level query doesn't work"
+        )
+    }
+
     @Test
     fun `test alert parsing`() {
         val alert = randomAlert()