[Backport 2.x] support rangeQuery and regexpQuery in constant_keyword field type

CHANGELOG.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add basic aggregation support for derived fields ([#14618](https://github.com/opensearch-project/OpenSearch/pull/14618))
 - Add ThreadContextPermission for markAsSystemContext and allow core to perform the method ([#15016](https://github.com/opensearch-project/OpenSearch/pull/15016))
 - Add ThreadContextPermission for stashAndMergeHeaders and stashWithOrigin ([#15039](https://github.com/opensearch-project/OpenSearch/pull/15039))
+- Add `rangeQuery` and `regexpQuery` for `constant_keyword` field type ([#14711](https://github.com/opensearch-project/OpenSearch/pull/14711))
 
 ### Dependencies
 - Bump `org.apache.commons:commons-lang3` from 3.14.0 to 3.15.0 ([#14861](https://github.com/opensearch-project/OpenSearch/pull/14861))

rest-api-spec/src/main/resources/rest-api-spec/test/index/110_constant_keyword.yml

@@ -1,17 +1,13 @@
+# The test setup includes two parts:
+# part1: test mapping and indexing
+# part2: test query
 ---
-# The test setup includes:
-# - Create index with constant_keyword field type
-# - Check mapping
-# - Index two example documents
-# - Search
-# - Delete Index when connection is teardown
-
-"Mappings and Supported queries":
+"Mappings and Indexing":
   - skip:
       version: " - 2.15.99"
       reason: "fixed in 2.16.0"
 
-  # Create index with constant_keyword field type
+  # Create indices with constant_keyword field type
   - do:
       indices.create:
         index: test
@@ -22,7 +18,7 @@
                 type: "constant_keyword"
                 value: "1"
 
-  # Index document
+  # Index documents to test integer and string are both ok.
   - do:
       index:
         index: test
@@ -39,6 +35,7 @@
           "genre": 1
         }
 
+  # Refresh
   - do:
       indices.refresh:
         index: test
@@ -54,6 +51,7 @@
   # Verify Document Count
   - do:
       search:
+        index: test
         body: {
           query: {
             match_all: {}
@@ -68,3 +66,267 @@
   - do:
       indices.delete:
         index: test
+
+---
+"Queries":
+  - skip:
+      version: " - 2.99.99"
+      reason: "rangeQuery and regexpQuery are supported in 3.0.0 in main branch"
+
+  - do:
+      indices.create:
+        index: test1
+        body:
+          mappings:
+            properties:
+              genre:
+                type: "constant_keyword"
+                value: "d3efault"
+
+  # Index documents to test query.
+  - do:
+      index:
+        index: test1
+        id: 1
+        body: {
+          "genre": "d3efault"
+        }
+
+  # Refresh
+  - do:
+      indices.refresh:
+        index: test1
+
+  # Test rangeQuery
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                gte: "d3efault"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                from: "d3efault",
+                "include_lower": "false"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 0 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                lte: "d3efault"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                to: "d3efault",
+                include_upper: "false"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 0 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                from: "d3efault",
+                to: "d3efault",
+                include_lower: "false",
+                include_upper: "true"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 0 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                from: "d3efault",
+                to: "d3efault",
+                include_lower: "true",
+                include_upper: "false"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 0 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                from: null,
+                to: null
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                from: "d3efault",
+                to: "d3efault",
+                include_lower: "true",
+                include_upper: "true"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            range: {
+              genre: {
+                from: "d3efaul",
+                to: "d3efault1",
+                include_lower: "true",
+                include_upper: "true"
+              }
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  # Test regexpQuery
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            regexp: {
+              "genre":"d.*"
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            regexp: {
+              "genre":"d\\defau[a-z]?t"
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            regexp: {
+              "genre":"d\\defa[a-z]?t"
+            }
+          }
+        }
+
+  - length: { hits.hits: 0 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            regexp: {
+              "genre":"d3efa[a-z]{3,3}"
+            }
+          }
+        }
+
+  - length: { hits.hits: 1 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            regexp: {
+              "genre":"d3efa[a-z]{4,4}"
+            }
+          }
+        }
+
+  - length: { hits.hits: 0 }
+
+  - do:
+      search:
+        index: test1
+        body: {
+          query: {
+            match_all: {}
+          }
+        }
+
+  - length: { hits.hits: 1 }
+  - match: { hits.hits.0._source.genre: "d3efault" }
+
+  # Delete Index when connection is teardown
+  - do:
+      indices.delete:
+        index: test1

server/src/main/java/org/opensearch/index/mapper/ConstantFieldType.java

@@ -76,7 +76,7 @@ public final boolean isAggregatable() {
      */
     protected abstract boolean matches(String pattern, boolean caseInsensitive, QueryShardContext context);
 
-    private static String valueToString(Object value) {
+    static String valueToString(Object value) {
         return value instanceof BytesRef ? ((BytesRef) value).utf8ToString() : value.toString();
     }