json-valid PPL function

core/src/main/java/org/opensearch/sql/expression/DSL.java

@@ -683,6 +683,10 @@ public static FunctionExpression notLike(Expression... expressions) {
     return compile(FunctionProperties.None, BuiltinFunctionName.NOT_LIKE, expressions);
   }
 
+  public static FunctionExpression jsonValid(Expression... expressions) {
+    return compile(FunctionProperties.None, BuiltinFunctionName.JSON_VALID, expressions);
+  }
+
   public static Aggregator avg(Expression... expressions) {
     return aggregate(BuiltinFunctionName.AVG, expressions);
   }

core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionName.java

@@ -204,6 +204,9 @@ public enum BuiltinFunctionName {
   TRIM(FunctionName.of("trim")),
   UPPER(FunctionName.of("upper")),
 
+  /** Json Functions. */
+  JSON_VALID(FunctionName.of("json_valid")),
+
   /** NULL Test. */
   IS_NULL(FunctionName.of("is null")),
   IS_NOT_NULL(FunctionName.of("is not null")),

core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionRepository.java

@@ -28,6 +28,7 @@
 import org.opensearch.sql.expression.datetime.DateTimeFunctions;
 import org.opensearch.sql.expression.datetime.IntervalClause;
 import org.opensearch.sql.expression.ip.IPFunctions;
+import org.opensearch.sql.expression.json.JsonFunctions;
 import org.opensearch.sql.expression.operator.arthmetic.ArithmeticFunctions;
 import org.opensearch.sql.expression.operator.arthmetic.MathematicalFunctions;
 import org.opensearch.sql.expression.operator.convert.TypeCastOperators;
@@ -83,6 +84,7 @@ public static synchronized BuiltinFunctionRepository getInstance() {
       SystemFunctions.register(instance);
       OpenSearchFunctions.register(instance);
       IPFunctions.register(instance);
+      JsonFunctions.register(instance);
     }
     return instance;
   }

core/src/main/java/org/opensearch/sql/expression/json/JsonFunctions.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.expression.json;
+
+import static org.opensearch.sql.data.type.ExprCoreType.BOOLEAN;
+import static org.opensearch.sql.data.type.ExprCoreType.STRING;
+import static org.opensearch.sql.expression.function.FunctionDSL.define;
+import static org.opensearch.sql.expression.function.FunctionDSL.impl;
+
+import lombok.experimental.UtilityClass;
+import org.opensearch.sql.expression.function.BuiltinFunctionName;
+import org.opensearch.sql.expression.function.BuiltinFunctionRepository;
+import org.opensearch.sql.expression.function.DefaultFunctionResolver;
+import org.opensearch.sql.utils.JsonUtils;
+
+@UtilityClass
+public class JsonFunctions {
+  public void register(BuiltinFunctionRepository repository) {
+    repository.register(jsonValid());
+  }
+
+  private DefaultFunctionResolver jsonValid() {
+    return define(
+        BuiltinFunctionName.JSON_VALID.getName(), impl(JsonUtils::isValidJson, BOOLEAN, STRING));
+  }
+}

core/src/main/java/org/opensearch/sql/utils/JsonUtils.java

@@ -0,0 +1,31 @@
+package org.opensearch.sql.utils;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.experimental.UtilityClass;
+import org.opensearch.sql.data.model.ExprValue;
+import org.opensearch.sql.data.model.ExprValueUtils;
+
+@UtilityClass
+public class JsonUtils {
+  /**
+   * Checks if given JSON string can be parsed as valid JSON.
+   *
+   * @param jsonExprValue JSON string (e.g. "{\"hello\": \"world\"}").
+   * @return true if the string can be parsed as valid JSON, else false.
+   */
+  public static ExprValue isValidJson(ExprValue jsonExprValue) {
+    ObjectMapper objectMapper = new ObjectMapper();
+
+    if (jsonExprValue.isNull() || jsonExprValue.isMissing()) {
+      return ExprValueUtils.LITERAL_FALSE;
+    }
+
+    try {
+      objectMapper.readTree(jsonExprValue.stringValue());
+      return ExprValueUtils.LITERAL_TRUE;
+    } catch (JsonProcessingException e) {
+      return ExprValueUtils.LITERAL_FALSE;
+    }
+  }
+}

core/src/test/java/org/opensearch/sql/expression/json/JsonFunctionsTest.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.expression.json;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.opensearch.sql.data.model.ExprValueUtils.LITERAL_FALSE;
+import static org.opensearch.sql.data.model.ExprValueUtils.LITERAL_MISSING;
+import static org.opensearch.sql.data.model.ExprValueUtils.LITERAL_NULL;
+import static org.opensearch.sql.data.model.ExprValueUtils.LITERAL_TRUE;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.opensearch.sql.data.model.ExprValue;
+import org.opensearch.sql.data.model.ExprValueUtils;
+import org.opensearch.sql.exception.ExpressionEvaluationException;
+import org.opensearch.sql.expression.DSL;
+import org.opensearch.sql.expression.FunctionExpression;
+
+@ExtendWith(MockitoExtension.class)
+public class JsonFunctionsTest {
+  private static final ExprValue JsonNestedObject =
+      ExprValueUtils.stringValue("{\"a\":\"1\",\"b\":{\"c\":\"2\",\"d\":\"3\"}}");
+  private static final ExprValue JsonObject =
+      ExprValueUtils.stringValue("{\"a\":\"1\",\"b\":\"2\"}");
+  private static final ExprValue JsonArray = ExprValueUtils.stringValue("[1, 2, 3, 4]");
+  private static final ExprValue JsonScalarString = ExprValueUtils.stringValue("\"abc\"");
+  private static final ExprValue JsonEmptyString = ExprValueUtils.stringValue("");
+  private static final ExprValue JsonInvalidObject =
+      ExprValueUtils.stringValue("{\"invalid\":\"json\", \"string\"}");
+  private static final ExprValue JsonInvalidScalar = ExprValueUtils.stringValue("abc");
+
+  @Test
+  public void json_valid_returns_false() {
+    assertEquals(LITERAL_FALSE, execute(JsonInvalidObject));
+    assertEquals(LITERAL_FALSE, execute(JsonInvalidScalar));
+    assertEquals(LITERAL_FALSE, execute(LITERAL_NULL));
+    assertEquals(LITERAL_FALSE, execute(LITERAL_MISSING));
+  }
+
+  @Test
+  public void json_valid_throws_ExpressionEvaluationException() {
+    assertThrows(
+        ExpressionEvaluationException.class, () -> execute(ExprValueUtils.booleanValue(true)));
+  }
+
+  @Test
+  public void json_valid_returns_true() {
+    assertEquals(LITERAL_TRUE, execute(JsonNestedObject));
+    assertEquals(LITERAL_TRUE, execute(JsonObject));
+    assertEquals(LITERAL_TRUE, execute(JsonArray));
+    assertEquals(LITERAL_TRUE, execute(JsonScalarString));
+    assertEquals(LITERAL_TRUE, execute(JsonEmptyString));
+  }
+
+  private ExprValue execute(ExprValue jsonString) {
+    FunctionExpression exp = DSL.jsonValid(DSL.literal(jsonString));
+    return exp.valueOf();
+  }
+}

docs/category.json

@@ -34,6 +34,7 @@
     "user/ppl/functions/datetime.rst",
     "user/ppl/functions/expressions.rst",
     "user/ppl/functions/ip.rst",
+    "user/ppl/functions/json.rst",
     "user/ppl/functions/math.rst",
     "user/ppl/functions/relevance.rst",
     "user/ppl/functions/string.rst"

docs/user/dql/metadata.rst

@@ -35,7 +35,7 @@ Example 1: Show All Indices Information
 SQL query::
 
     os> SHOW TABLES LIKE '%'
-    fetched rows / total rows = 10/10
+    fetched rows / total rows = 11/11
     +----------------+-------------+-----------------+------------+---------+----------+------------+-----------+---------------------------+----------------+
     | TABLE_CAT      | TABLE_SCHEM | TABLE_NAME      | TABLE_TYPE | REMARKS | TYPE_CAT | TYPE_SCHEM | TYPE_NAME | SELF_REFERENCING_COL_NAME | REF_GENERATION |
     |----------------+-------------+-----------------+------------+---------+----------+------------+-----------+---------------------------+----------------|
@@ -44,6 +44,7 @@ SQL query::
     | docTestCluster | null        | accounts        | BASE TABLE | null    | null     | null       | null      | null                      | null           |
     | docTestCluster | null        | apache          | BASE TABLE | null    | null     | null       | null      | null                      | null           |
     | docTestCluster | null        | books           | BASE TABLE | null    | null     | null       | null      | null                      | null           |
+    | docTestCluster | null        | json_test       | BASE TABLE | null    | null     | null       | null      | null                      | null           |
     | docTestCluster | null        | nested          | BASE TABLE | null    | null     | null       | null      | null                      | null           |
     | docTestCluster | null        | nyc_taxi        | BASE TABLE | null    | null     | null       | null      | null                      | null           |
     | docTestCluster | null        | people          | BASE TABLE | null    | null     | null       | null      | null                      | null           |

docs/user/ppl/functions/json.rst

@@ -0,0 +1,36 @@
+====================
+JSON Functions
+====================
+
+.. rubric:: Table of contents
+
+.. contents::
+   :local:
+   :depth: 1
+
+JSON_VALID
+----------
+
+Description
+>>>>>>>>>>>
+
+Usage: `json_valid(json_string)` checks if `json_string` is a valid JSON-encoded string.
+
+Argument type: STRING
+
+Return type: BOOLEAN
+
+Example::
+
+    > source=json_test | eval is_valid = json_valid(json_string) | fields test_name, json_string, is_valid
+    fetched rows / total rows = 6/6
+    +---------------------+---------------------------------+----------+
+    | test_name           | json_string                     | is_valid |
+    |---------------------|---------------------------------|----------|
+    | json nested object  | {"a":"1","b":{"c":"2","d":"3"}} | True     |
+    | json object         | {"a":"1","b":"2"}               | True     |
+    | json array          | [1, 2, 3, 4]                    | True     |
+    | json scalar string  | "abc"                           | True     |
+    | json empty string   |                                 | True     |
+    | json invalid object | {"invalid":"json", "string"}    | False    |
+    +---------------------+---------------------------------+----------+

doctest/test_data/json_test.json

@@ -0,0 +1,6 @@
+{"test_name":"json nested object", "json_string":"{\"a\":\"1\",\"b\":{\"c\":\"2\",\"d\":\"3\"}}"}
+{"test_name":"json object", "json_string":"{\"a\":\"1\",\"b\":\"2\"}"}
+{"test_name":"json array", "json_string":"[1, 2, 3, 4]"}
+{"test_name":"json scalar string", "json_string":"\"abc\""}
+{"test_name":"json empty string","json_string":""}
+{"test_name":"json invalid object", "json_string":"{\"invalid\":\"json\", \"string\"}"}

doctest/test_docs.py

@@ -30,6 +30,7 @@
 NESTED = "nested"
 DATASOURCES = ".ql-datasources"
 WEBLOGS = "weblogs"
+JSON_TEST = "json_test"
 
 class DocTestConnection(OpenSearchConnection):
 
@@ -123,6 +124,7 @@ def set_up_test_indices(test):
     load_file("nested_objects.json", index_name=NESTED)
     load_file("datasources.json", index_name=DATASOURCES)
     load_file("weblogs.json", index_name=WEBLOGS)
+    load_file("json_test.json", index_name=JSON_TEST)
 
 
 def load_file(filename, index_name):
@@ -151,7 +153,7 @@ def set_up(test):
 
 def tear_down(test):
     # drop leftover tables after each test
-    test_data_client.indices.delete(index=[ACCOUNTS, EMPLOYEES, PEOPLE, ACCOUNT2, NYC_TAXI, BOOKS, APACHE, WILDCARD, NESTED, WEBLOGS], ignore_unavailable=True)
+    test_data_client.indices.delete(index=[ACCOUNTS, EMPLOYEES, PEOPLE, ACCOUNT2, NYC_TAXI, BOOKS, APACHE, WILDCARD, NESTED, WEBLOGS, JSON_TEST], ignore_unavailable=True)
 
 
 docsuite = partial(doctest.DocFileSuite,

integ-test/src/test/java/org/opensearch/sql/legacy/SQLIntegTestCase.java

@@ -22,6 +22,7 @@
 import static org.opensearch.sql.legacy.TestUtils.getGameOfThronesIndexMapping;
 import static org.opensearch.sql.legacy.TestUtils.getGeopointIndexMapping;
 import static org.opensearch.sql.legacy.TestUtils.getJoinTypeIndexMapping;
+import static org.opensearch.sql.legacy.TestUtils.getJsonTestIndexMapping;
 import static org.opensearch.sql.legacy.TestUtils.getLocationIndexMapping;
 import static org.opensearch.sql.legacy.TestUtils.getMappingFile;
 import static org.opensearch.sql.legacy.TestUtils.getNestedSimpleIndexMapping;
@@ -745,7 +746,12 @@ public enum Index {
         TestsConstants.TEST_INDEX_GEOPOINT,
         "dates",
         getGeopointIndexMapping(),
-        "src/test/resources/geopoints.json");
+        "src/test/resources/geopoints.json"),
+    JSON_TEST(
+        TestsConstants.TEST_INDEX_JSON_TEST,
+        "json",
+        getJsonTestIndexMapping(),
+        "src/test/resources/json_test.json");
 
     private final String name;
     private final String type;

integ-test/src/test/java/org/opensearch/sql/legacy/TestUtils.java

@@ -250,6 +250,11 @@ public static String getGeopointIndexMapping() {
     return getMappingFile(mappingFile);
   }
 
+  public static String getJsonTestIndexMapping() {
+    String mappingFile = "json_test_index_mapping.json";
+    return getMappingFile(mappingFile);
+  }
+
   public static void loadBulk(Client client, String jsonPath, String defaultIndex)
       throws Exception {
     System.out.println(String.format("Loading file %s into opensearch cluster", jsonPath));

integ-test/src/test/java/org/opensearch/sql/legacy/TestsConstants.java

@@ -58,6 +58,7 @@ public class TestsConstants {
   public static final String TEST_INDEX_MULTI_NESTED_TYPE = TEST_INDEX + "_multi_nested";
   public static final String TEST_INDEX_NESTED_WITH_NULLS = TEST_INDEX + "_nested_with_nulls";
   public static final String TEST_INDEX_GEOPOINT = TEST_INDEX + "_geopoint";
+  public static final String TEST_INDEX_JSON_TEST = TEST_INDEX + "_json_test";
   public static final String DATASOURCES = ".ql-datasources";
 
   public static final String DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";

integ-test/src/test/java/org/opensearch/sql/ppl/JsonFunctionsIT.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.ppl;
+
+import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_JSON_TEST;
+import static org.opensearch.sql.util.MatcherUtils.rows;
+import static org.opensearch.sql.util.MatcherUtils.schema;
+import static org.opensearch.sql.util.MatcherUtils.verifyDataRows;
+import static org.opensearch.sql.util.MatcherUtils.verifySchema;
+
+import java.io.IOException;
+import org.json.JSONObject;
+import org.junit.jupiter.api.Test;
+
+public class JsonFunctionsIT extends PPLIntegTestCase {
+  @Override
+  public void init() throws IOException {
+    loadIndex(Index.JSON_TEST);
+  }
+
+  @Test
+  public void test_json_valid() throws IOException {
+    JSONObject result;
+
+    result =
+        executeQuery(
+            String.format(
+                "source=%s | where json_valid(json_string) | fields test_name",
+                TEST_INDEX_JSON_TEST));
+    verifySchema(result, schema("test_name", null, "string"));
+    verifyDataRows(
+        result,
+        rows("json nested object"),
+        rows("json object"),
+        rows("json array"),
+        rows("json scalar string"),
+        rows("json empty string"));
+  }
+
+  @Test
+  public void test_not_json_valid() throws IOException {
+    JSONObject result;
+
+    result =
+        executeQuery(
+            String.format(
+                "source=%s | where not json_valid(json_string) | fields test_name",
+                TEST_INDEX_JSON_TEST));
+    verifySchema(result, schema("test_name", null, "string"));
+    verifyDataRows(result, rows("json invalid object"), rows("json null"));
+  }
+}

integ-test/src/test/resources/indexDefinitions/json_test_index_mapping.json

@@ -0,0 +1,12 @@
+{
+  "mappings": {
+    "properties": {
+      "test_name": {
+        "type": "keyword"
+      },
+      "json_string": {
+        "type": "keyword"
+      }
+    }
+  }
+}

integ-test/src/test/resources/json_test.json

@@ -0,0 +1,14 @@
+{"index":{"_id":"0"}}
+{"test_name":"json nested object", "json_string":"{\"a\":\"1\",\"b\":{\"c\":\"2\",\"d\":\"3\"}}"}
+{"index":{"_id":"1"}}
+{"test_name":"json object", "json_string":"{\"a\":\"1\",\"b\":\"2\"}"}
+{"index":{"_id":"2"}}
+{"test_name":"json array", "json_string":"[1, 2, 3, 4]"}
+{"index":{"_id":"3"}}
+{"test_name":"json scalar string", "json_string":"\"abc\""}
+{"index":{"_id":"4"}}
+{"test_name":"json empty string","json_string":""}
+{"index":{"_id":"5"}}
+{"test_name":"json invalid object", "json_string":"{\"invalid\":\"json\", \"string\"}"}
+{"index":{"_id":"6"}}
+{"test_name":"json null", "json_string":null}

ppl/src/main/antlr/OpenSearchPPLLexer.g4

@@ -332,6 +332,9 @@ ISNULL:                             'ISNULL';
 ISNOTNULL:                          'ISNOTNULL';
 CIDRMATCH:                          'CIDRMATCH';
 
+// JSON FUNCTIONS
+JSON_VALID:                         'JSON_VALID';
+
 // FLOWCONTROL FUNCTIONS
 IFNULL:                             'IFNULL';
 NULLIF:                             'NULLIF';