SERVER-53146: Specify input to explain command in IDL

10 files changed, 264 insertions, 213 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 1f472114232..9387bcf0fe6 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -578,6 +578,7 @@ env.Library(
         'drop.idl',
         'drop_database.idl',
         'drop_indexes.idl',
+        "explain.idl",
         'list_collections.idl',
         'list_indexes.idl',
     ],
@@ -590,6 +591,7 @@ env.Library(
         '$BUILD_DIR/mongo/bson/mutable/mutable_bson',
         '$BUILD_DIR/mongo/db/catalog/collection_options_idl',
         '$BUILD_DIR/mongo/db/commands/create_command',
+        '$BUILD_DIR/mongo/db/query/explain_options',
         '$BUILD_DIR/mongo/idl/idl_parser',
         '$BUILD_DIR/mongo/rpc/command_status',
         '$BUILD_DIR/mongo/rpc/rpc',
@@ -2277,6 +2279,7 @@ if wiredtiger:
             'dbdirectclient_test.cpp',
             'dbmessage_test.cpp',
             'db_raii_test.cpp',
+            "explain_test.cpp",
             'field_parser_test.cpp',
             'field_ref_set_test.cpp',
             'field_ref_test.cpp',
@@ -2328,6 +2331,7 @@ if wiredtiger:
             '$BUILD_DIR/mongo/db/catalog/index_build_entry_idl',
             '$BUILD_DIR/mongo/db/mongohasher',
             '$BUILD_DIR/mongo/db/op_msg_fuzzer_fixture',
+            '$BUILD_DIR/mongo/db/query/explain_options',
             '$BUILD_DIR/mongo/db/query/query_test_service_context',
             '$BUILD_DIR/mongo/db/storage/wiredtiger/storage_wiredtiger',
             '$BUILD_DIR/mongo/executor/async_timer_mock',
diff --git a/src/mongo/db/commands/explain_cmd.cpp b/src/mongo/db/commands/explain_cmd.cpp
index 665ea42bc4b..8f754f6e1d4 100644
--- a/src/mongo/db/commands/explain_cmd.cpp
+++ b/src/mongo/db/commands/explain_cmd.cpp
@@ -31,6 +31,7 @@
 
 #include "mongo/db/command_can_run_here.h"
 #include "mongo/db/commands.h"
+#include "mongo/db/explain_gen.h"
 #include "mongo/db/query/explain.h"
 #include "mongo/util/str.h"
 
@@ -151,16 +152,15 @@ private:
 std::unique_ptr<CommandInvocation> CmdExplain::parse(OperationContext* opCtx,
                                                      const OpMsgRequest& request) {
     CommandHelpers::uassertNoDocumentSequences(getName(), request);
-    std::string dbname = request.getDatabase().toString();
-    const BSONObj& cmdObj = request.body;
-    uassert(ErrorCodes::FailedToParse,
-            "Unrecognized field 'jsonSchema'. This command may be meant for a mongocryptd process.",
-            !cmdObj.hasField("jsonSchema"_sd));
-    ExplainOptions::Verbosity verbosity = uassertStatusOK(ExplainOptions::parseCmdBSON(cmdObj));
-    uassert(ErrorCodes::BadValue,
-            "explain command requires a nested object",
-            cmdObj.firstElement().type() == Object);
-    auto explainedObj = cmdObj.firstElement().Obj();
+
+    // To enforce API versioning
+    auto cmdObj = ExplainCmd::parse(
+        IDLParserErrorContext(ExplainCmd::kCommandName,
+                              APIParameters::get(opCtx).getAPIStrict().value_or(false)),
+        request.body);
+    std::string dbname = cmdObj.getDbName().toString();
+    ExplainOptions::Verbosity verbosity = cmdObj.getVerbosity();
+    auto explainedObj = cmdObj.getCommandParameter();
 
     // Extract 'comment' field from the 'explainedObj' only if there is no top-level comment.
     auto commentField = explainedObj["comment"];
diff --git a/src/mongo/db/explain.idl b/src/mongo/db/explain.idl
new file mode 100644
index 00000000000..866fa670608
--- /dev/null
+++ b/src/mongo/db/explain.idl
@@ -0,0 +1,67 @@
+# Copyright (C) 2018-present MongoDB, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the Server Side Public License, version 1,
+# as published by MongoDB, Inc.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# Server Side Public License for more details.
+#
+# You should have received a copy of the Server Side Public License
+# along with this program. If not, see
+# <http:#www.mongodb.com/licensing/server-side-public-license>.
+#
+# As a special exception, the copyright holders give permission to link the
+# code of portions of this program with the OpenSSL library under certain
+# conditions as described in each individual source file and distribute
+# linked combinations including the program with the OpenSSL library. You
+# must comply with the Server Side Public License in all respects for
+# all of the code used other than as permitted herein. If you modify file(s)
+# with this exception, you may extend this exception to your version of the
+# file(s), but you are not obligated to do so. If you do not wish to do so,
+# delete this exception statement from your version. If you delete this
+# exception statement from all source files in the program, then also delete
+# it in the license file.
+#
+
+global:
+    cpp_namespace: "mongo"
+
+imports:
+    - "mongo/idl/basic_types.idl"
+    - "mongo/db/query/explain_verbosity.idl"
+
+commands:
+    explain:
+        description: "Parser for the explain command"
+        command_name: explain
+        namespace: type
+        type: object
+        cpp_name: ExplainCmd
+        strict: true
+        api_version: "1"
+        fields:
+            verbosity:
+                description: "The verbosity for explain command."
+                type: Verbosity
+                default : kExecAllPlans
+            # TODO SERVER-48560: we ingest these fields for compatibility with 4.4,
+            # whose mongoS incorrectly adds them to the explain command for an
+            # aggregation instead of adding them into the wrapped aggregate command
+            # itself. Remove these fields when 5.0 becomes last-lts.
+            collation:
+                type: IDLAnyType
+                ignore: true
+                unstable: true
+            use44SortKeys:
+                type: IDLAnyType
+                ignore: true
+                unstable: true
+            useNewUpsert:
+                type: IDLAnyType
+                ignore: true
+                unstable: true           
+        # Dummy reply type as we won't use it to parse explain reply.
+        reply_type: OkReply
\ No newline at end of file
diff --git a/src/mongo/db/explain_test.cpp b/src/mongo/db/explain_test.cpp
new file mode 100644
index 00000000000..9b7d3df9c06
--- /dev/null
+++ b/src/mongo/db/explain_test.cpp
@@ -0,0 +1,120 @@
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/bson/bsonmisc.h"
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/bson/json.h"
+#include "mongo/db/explain_gen.h"
+#include "mongo/db/query/explain_options.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+
+using Verbosity = explain::VerbosityEnum;
+
+TEST(ExplainTest, VerbosityEnumToStringReturnsCorrectValues) {
+    ASSERT_EQ(explain::Verbosity_serializer(Verbosity::kQueryPlanner), "queryPlanner"_sd);
+    ASSERT_EQ(explain::Verbosity_serializer(Verbosity::kExecStats), "executionStats"_sd);
+    ASSERT_EQ(explain::Verbosity_serializer(Verbosity::kExecAllPlans), "allPlansExecution"_sd);
+}
+
+TEST(ExplainTest, ExplainSerializeToBSONCorrectly) {
+    ASSERT_BSONOBJ_EQ(BSON("verbosity"
+                           << "queryPlanner"),
+                      ExplainOptions::toBSON(Verbosity::kQueryPlanner));
+    ASSERT_BSONOBJ_EQ(BSON("verbosity"
+                           << "executionStats"),
+                      ExplainOptions::toBSON(Verbosity::kExecStats));
+    ASSERT_BSONOBJ_EQ(BSON("verbosity"
+                           << "allPlansExecution"),
+                      ExplainOptions::toBSON(Verbosity::kExecAllPlans));
+}
+
+TEST(ExplainTest, CanParseExplainVerbosity) {
+    auto verbosity =
+        ExplainCmd::parse(IDLParserErrorContext("explain"),
+                          fromjson("{explain: {}, verbosity: 'queryPlanner', $db: 'dummy'}"))
+            .getVerbosity();
+    ASSERT(verbosity == Verbosity::kQueryPlanner);
+    verbosity =
+        ExplainCmd::parse(IDLParserErrorContext("explain"),
+                          fromjson("{explain: {}, verbosity: 'executionStats', $db: 'dummy'}"))
+            .getVerbosity();
+    ASSERT(verbosity == Verbosity::kExecStats);
+    verbosity =
+        ExplainCmd::parse(IDLParserErrorContext("explain"),
+                          fromjson("{explain: {}, verbosity: 'allPlansExecution', $db: 'dummy'}"))
+            .getVerbosity();
+    ASSERT(verbosity == Verbosity::kExecAllPlans);
+}
+
+TEST(ExplainTest, ParsingFailsIfVerbosityIsNotAString) {
+    ASSERT_THROWS_CODE(ExplainCmd::parse(IDLParserErrorContext("explain"),
+                                         fromjson("{explain: {}, verbosity: 1}")),
+                       DBException,
+                       ErrorCodes::TypeMismatch);
+    ASSERT_THROWS_CODE(ExplainCmd::parse(IDLParserErrorContext("explain"),
+                                         fromjson("{explain: {}, verbosity: {foo: 'bar'}}")),
+                       DBException,
+                       ErrorCodes::TypeMismatch);
+}
+
+TEST(ExplainTest, ParsingFailsIfVerbosityStringIsNotRecognized) {
+    ASSERT_THROWS_CODE(ExplainCmd::parse(IDLParserErrorContext("explain"),
+                                         fromjson("{explain: {}, verbosity: 'badVerbosity'}")),
+                       DBException,
+                       ErrorCodes::BadValue);
+}
+
+TEST(ExplainTest, ParsingFailsIfFirstElementIsNotAnObject) {
+    ASSERT_THROWS_CODE(ExplainCmd::parse(IDLParserErrorContext("explain"),
+                                         fromjson("{explain: 1, verbosity: 'queryPlanner'}")),
+                       DBException,
+                       40414);
+}
+
+TEST(ExplainTest, ParsingFailsIfUnknownFieldInCommandObject) {
+    ASSERT_THROWS_CODE(
+        ExplainCmd::parse(IDLParserErrorContext("explain"),
+                          fromjson("{explain: {}, verbosity: 'queryPlanner', unknownField: true}")),
+        DBException,
+        40415);
+}
+
+TEST(ExplainTest, CanParseGenericCommandArguments) {
+    ExplainCmd::parse(
+        IDLParserErrorContext("explain"),
+        fromjson("{explain: {}, verbosity: 'queryPlanner', comment: true, $db: 'test'}"));
+}
+
+}  // namespace
+}  // namespace mongo
diff --git a/src/mongo/db/query/SConscript b/src/mongo/db/query/SConscript
index 6633ad8c4d4..ed2627eab26 100644
--- a/src/mongo/db/query/SConscript
+++ b/src/mongo/db/query/SConscript
@@ -126,6 +126,7 @@ env.Library(
     target="explain_options",
     source=[
         "explain_options.cpp",
+        "explain_verbosity.idl"
     ],
     LIBDEPS=[
         "$BUILD_DIR/mongo/base",
@@ -289,7 +290,6 @@ env.CppUnitTest(
         "classic_stage_builder_test.cpp",
         "count_command_test.cpp",
         "cursor_response_test.cpp",
-        "explain_options_test.cpp",
         "get_executor_test.cpp",
         "getmore_request_test.cpp",
         "hint_parser_test.cpp",
diff --git a/src/mongo/db/query/explain_options.cpp b/src/mongo/db/query/explain_options.cpp
index 772681434fc..dc8a8c15257 100644
--- a/src/mongo/db/query/explain_options.cpp
+++ b/src/mongo/db/query/explain_options.cpp
@@ -37,66 +37,10 @@
 
 namespace mongo {
 
-constexpr StringData ExplainOptions::kCommandName;
 constexpr StringData ExplainOptions::kVerbosityName;
-constexpr StringData ExplainOptions::kQueryPlannerVerbosityStr;
-constexpr StringData ExplainOptions::kExecStatsVerbosityStr;
-constexpr StringData ExplainOptions::kAllPlansExecutionVerbosityStr;
 
 StringData ExplainOptions::verbosityString(ExplainOptions::Verbosity verbosity) {
-    switch (verbosity) {
-        case Verbosity::kQueryPlanner:
-            return kQueryPlannerVerbosityStr;
-        case Verbosity::kExecStats:
-            return kExecStatsVerbosityStr;
-        case Verbosity::kExecAllPlans:
-            return kAllPlansExecutionVerbosityStr;
-        default:
-            MONGO_UNREACHABLE;
-    }
-}
-
-StatusWith<ExplainOptions::Verbosity> ExplainOptions::parseCmdBSON(const BSONObj& cmdObj) {
-    auto verbosity = Verbosity::kExecAllPlans;
-    for (auto&& field : cmdObj) {
-        auto fieldName = field.fieldNameStringData();
-
-        if (fieldName == kCommandName) {
-            if (BSONType::Object != field.type()) {
-                return Status(ErrorCodes::FailedToParse,
-                              "explain command requires a nested object");
-            }
-        } else if (fieldName == kVerbosityName) {
-            if (field.type() != BSONType::String) {
-                return Status(ErrorCodes::FailedToParse, "explain verbosity must be a string");
-            }
-
-            auto verbStr = field.valueStringData();
-            if (verbStr == kQueryPlannerVerbosityStr) {
-                verbosity = Verbosity::kQueryPlanner;
-            } else if (verbStr == kExecStatsVerbosityStr) {
-                verbosity = Verbosity::kExecStats;
-            } else if (verbStr != kAllPlansExecutionVerbosityStr) {
-                return Status(ErrorCodes::FailedToParse,
-                              str::stream()
-                                  << "verbosity string must be one of {'"
-                                  << kQueryPlannerVerbosityStr << "', '" << kExecStatsVerbosityStr
-                                  << "', '" << kAllPlansExecutionVerbosityStr << "'}");
-            }
-        } else if (fieldName == "collation" || fieldName == "use44SortKeys" ||
-                   fieldName == "useNewUpsert") {
-            // TODO SERVER-48560: we ingest these fields for compatibility with 4.4,
-            // whose mongoS incorrectly adds them to the explain command for an
-            // aggregation instead of adding them into the wrapped aggregate command
-            // itself. Remove this block when 5.0 becomes last-lts.
-            continue;
-        } else if (!isGenericArgument(fieldName)) {
-            return Status(ErrorCodes::InvalidOptions,
-                          str::stream() << "unexpected field '" << fieldName
-                                        << "' in explain command object");
-        }
-    }
-    return verbosity;
+    return Verbosity_serializer(verbosity);
 }
 
 BSONObj ExplainOptions::toBSON(ExplainOptions::Verbosity verbosity) {
diff --git a/src/mongo/db/query/explain_options.h b/src/mongo/db/query/explain_options.h
index d58a22677e5..a2a46ca355e 100644
--- a/src/mongo/db/query/explain_options.h
+++ b/src/mongo/db/query/explain_options.h
@@ -31,6 +31,7 @@
 
 #include "mongo/base/status.h"
 #include "mongo/bson/bsonobj.h"
+#include "mongo/db/query/explain_verbosity_gen.h"
 
 namespace mongo {
 
@@ -44,44 +45,16 @@ public:
      * The various supported verbosity levels for explain. The order is significant: the enum values
      * are assigned in order of increasing verbosity.
      */
-    enum class Verbosity {
-        // At all verbosities greater than or equal to QUERY_PLANNER, we display information about
-        // the plan selected and alternate rejected plans. Does not include any execution- related
-        // info. String alias is "queryPlanner".
-        kQueryPlanner = 0,
+    using Verbosity = explain::VerbosityEnum;
 
-        // At all verbosities greater than or equal to EXEC_STATS, we display a section of output
-        // containing both overall execution stats, and stats per stage in the execution tree.
-        // String alias is "execStats".
-        kExecStats = 1,
-
-        // At this verbosity level, we generate the execution stats for each rejected plan as well
-        // as the winning plan. String alias is "allPlansExecution".
-        kExecAllPlans = 2,
-    };
-
-    static constexpr StringData kCommandName = "explain"_sd;
     static constexpr StringData kVerbosityName = "verbosity"_sd;
 
-    // String representations for verbosity levels.
-    static constexpr StringData kQueryPlannerVerbosityStr = "queryPlanner"_sd;
-    static constexpr StringData kExecStatsVerbosityStr = "executionStats"_sd;
-    static constexpr StringData kAllPlansExecutionVerbosityStr = "allPlansExecution"_sd;
-
     /**
      * Converts an explain verbosity to its string representation.
      */
     static StringData verbosityString(ExplainOptions::Verbosity verbosity);
 
     /**
-     * Does some basic validation of the command BSON, then extracts and returns the explain
-     * verbosity.
-     *
-     * Returns a non-OK status if parsing fails.
-     */
-    static StatusWith<ExplainOptions::Verbosity> parseCmdBSON(const BSONObj& cmdObj);
-
-    /**
      * Converts 'verbosity' to its corresponding representation as a BSONObj containing explain
      * command parameters.
      */
diff --git a/src/mongo/db/query/explain_options_test.cpp b/src/mongo/db/query/explain_options_test.cpp
deleted file mode 100644
index 7a4a0e11260..00000000000
--- a/src/mongo/db/query/explain_options_test.cpp
+++ /dev/null
@@ -1,109 +0,0 @@
-/**
- *    Copyright (C) 2018-present MongoDB, Inc.
- *
- *    This program is free software: you can redistribute it and/or modify
- *    it under the terms of the Server Side Public License, version 1,
- *    as published by MongoDB, Inc.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    Server Side Public License for more details.
- *
- *    You should have received a copy of the Server Side Public License
- *    along with this program. If not, see
- *    <http://www.mongodb.com/licensing/server-side-public-license>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the Server Side Public License in all respects for
- *    all of the code used other than as permitted herein. If you modify file(s)
- *    with this exception, you may extend this exception to your version of the
- *    file(s), but you are not obligated to do so. If you do not wish to do so,
- *    delete this exception statement from your version. If you delete this
- *    exception statement from all source files in the program, then also delete
- *    it in the license file.
- */
-
-#include "mongo/platform/basic.h"
-
-#include "mongo/db/query/explain_options.h"
-
-#include "mongo/bson/bsonmisc.h"
-#include "mongo/bson/bsonobjbuilder.h"
-#include "mongo/bson/json.h"
-#include "mongo/unittest/unittest.h"
-
-namespace mongo {
-namespace {
-
-TEST(ExplainOptionsTest, VerbosityEnumToStringReturnsCorrectValues) {
-    ASSERT_EQ(ExplainOptions::verbosityString(ExplainOptions::Verbosity::kQueryPlanner),
-              "queryPlanner"_sd);
-    ASSERT_EQ(ExplainOptions::verbosityString(ExplainOptions::Verbosity::kExecStats),
-              "executionStats"_sd);
-    ASSERT_EQ(ExplainOptions::verbosityString(ExplainOptions::Verbosity::kExecAllPlans),
-              "allPlansExecution"_sd);
-}
-
-TEST(ExplainOptionsTest, ExplainOptionsSerializeToBSONCorrectly) {
-    ASSERT_BSONOBJ_EQ(BSON("verbosity"
-                           << "queryPlanner"),
-                      ExplainOptions::toBSON(ExplainOptions::Verbosity::kQueryPlanner));
-    ASSERT_BSONOBJ_EQ(BSON("verbosity"
-                           << "executionStats"),
-                      ExplainOptions::toBSON(ExplainOptions::Verbosity::kExecStats));
-    ASSERT_BSONOBJ_EQ(BSON("verbosity"
-                           << "allPlansExecution"),
-                      ExplainOptions::toBSON(ExplainOptions::Verbosity::kExecAllPlans));
-}
-
-TEST(ExplainOptionsTest, CanParseExplainVerbosity) {
-    auto verbosity = unittest::assertGet(
-        ExplainOptions::parseCmdBSON(fromjson("{explain: {}, verbosity: 'queryPlanner'}")));
-    ASSERT(verbosity == ExplainOptions::Verbosity::kQueryPlanner);
-    verbosity = unittest::assertGet(
-        ExplainOptions::parseCmdBSON(fromjson("{explain: {}, verbosity: 'executionStats'}")));
-    ASSERT(verbosity == ExplainOptions::Verbosity::kExecStats);
-    verbosity = unittest::assertGet(
-        ExplainOptions::parseCmdBSON(fromjson("{explain: {}, verbosity: 'allPlansExecution'}")));
-    ASSERT(verbosity == ExplainOptions::Verbosity::kExecAllPlans);
-}
-
-TEST(ExplainOptionsTest, ParsingFailsIfVerbosityIsNotAString) {
-    ASSERT_EQ(ExplainOptions::parseCmdBSON(fromjson("{explain: {}, verbosity: 1}")).getStatus(),
-              ErrorCodes::FailedToParse);
-    ASSERT_EQ(ExplainOptions::parseCmdBSON(fromjson("{explain: {}, verbosity: {foo: 'bar'}}"))
-                  .getStatus(),
-              ErrorCodes::FailedToParse);
-}
-
-TEST(ExplainOptionsTest, ParsingFailsIfVerbosityStringIsNotRecognized) {
-    ASSERT_EQ(ExplainOptions::parseCmdBSON(fromjson("{explain: {}, verbosity: 'badVerbosity'}"))
-                  .getStatus(),
-              ErrorCodes::FailedToParse);
-}
-
-TEST(ExplainOptionsTest, ParsingFailsIfFirstElementIsNotAnObject) {
-    ASSERT_EQ(ExplainOptions::parseCmdBSON(fromjson("{explain: 1, verbosity: 'queryPlanner'}"))
-                  .getStatus(),
-              ErrorCodes::FailedToParse);
-}
-
-TEST(ExplainOptionsTest, ParsingFailsIfUnknownFieldInCommandObject) {
-    ASSERT_EQ(ExplainOptions::parseCmdBSON(
-                  fromjson("{explain: {}, verbosity: 'queryPlanner', unknownField: true}"))
-                  .getStatus(),
-              ErrorCodes::InvalidOptions);
-}
-
-TEST(ExplainOptionsTest, CanParseGenericCommandArguments) {
-    ASSERT_OK(ExplainOptions::parseCmdBSON(
-                  fromjson("{explain: {}, verbosity: 'queryPlanner', comment: true, $db: 'test'}"))
-                  .getStatus());
-}
-
-}  // namespace
-}  // namespace mongo
diff --git a/src/mongo/db/query/explain_verbosity.idl b/src/mongo/db/query/explain_verbosity.idl
new file mode 100644
index 00000000000..5b6114e1e3c
--- /dev/null
+++ b/src/mongo/db/query/explain_verbosity.idl
@@ -0,0 +1,50 @@
+# Copyright (C) 2018-present MongoDB, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the Server Side Public License, version 1,
+# as published by MongoDB, Inc.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# Server Side Public License for more details.
+#
+# You should have received a copy of the Server Side Public License
+# along with this program. If not, see
+# <http:#www.mongodb.com/licensing/server-side-public-license>.
+#
+# As a special exception, the copyright holders give permission to link the
+# code of portions of this program with the OpenSSL library under certain
+# conditions as described in each individual source file and distribute
+# linked combinations including the program with the OpenSSL library. You
+# must comply with the Server Side Public License in all respects for
+# all of the code used other than as permitted herein. If you modify file(s)
+# with this exception, you may extend this exception to your version of the
+# file(s), but you are not obligated to do so. If you do not wish to do so,
+# delete this exception statement from your version. If you delete this
+# exception statement from all source files in the program, then also delete
+# it in the license file.
+#
+
+global:
+    cpp_namespace: "mongo::explain"
+  
+enums:
+    Verbosity:
+        description: "The various supported verbosity levels for explain. The order is significant: 
+                      the enum values are assigned in order of increasing verbosity"
+        type: string
+        values:
+            # At all verbosities greater than or equal to kQueryPlanner, we display information
+            # about the plan selected and alternate rejected plans. Does not include any
+            # execution-related info. String alias is "queryPlanner".
+            kQueryPlanner: "queryPlanner"
+
+            # At all verbosities greater than or equal to kExecStats, we display a section of output
+            # containing both overall execution stats, and stats per stage in the execution tree.
+            # String alias is "executionStats".
+            kExecStats: "executionStats"
+
+            # At this verbosity level, we generate the execution stats for each rejected plan as
+            # well as the winning plan. String alias is "allPlansExecution".
+            kExecAllPlans: "allPlansExecution"
\ No newline at end of file
diff --git a/src/mongo/s/commands/cluster_explain_cmd.cpp b/src/mongo/s/commands/cluster_explain_cmd.cpp
index ce2fb30491c..4a69c0360fa 100644
--- a/src/mongo/s/commands/cluster_explain_cmd.cpp
+++ b/src/mongo/s/commands/cluster_explain_cmd.cpp
@@ -30,6 +30,7 @@
 #include "mongo/platform/basic.h"
 
 #include "mongo/db/commands.h"
+#include "mongo/db/explain_gen.h"
 #include "mongo/db/query/explain.h"
 #include "mongo/idl/command_generic_argument.h"
 #include "mongo/s/query/cluster_find.h"
@@ -172,17 +173,18 @@ BSONObj makeExplainedObj(const BSONObj& outerObj, StringData dbName) {
 std::unique_ptr<CommandInvocation> ClusterExplainCmd::parse(OperationContext* opCtx,
                                                             const OpMsgRequest& request) {
     CommandHelpers::uassertNoDocumentSequences(getName(), request);
-    std::string dbName = request.getDatabase().toString();
-    const BSONObj& cmdObj = request.body;
-    uassert(ErrorCodes::FailedToParse,
-            "Unrecognized field 'jsonSchema'. This command may be meant for a mongocryptd process.",
-            !cmdObj.hasField("jsonSchema"_sd));
-    ExplainOptions::Verbosity verbosity = uassertStatusOK(ExplainOptions::parseCmdBSON(cmdObj));
 
+    // To enforce API versioning
+    auto cmdObj = ExplainCmd::parse(
+        IDLParserErrorContext(ExplainCmd::kCommandName,
+                              APIParameters::get(opCtx).getAPIStrict().value_or(false)),
+        request.body);
+    std::string dbName = cmdObj.getDbName().toString();
+    ExplainOptions::Verbosity verbosity = cmdObj.getVerbosity();
     // This is the nested command which we are explaining. We need to propagate generic
     // arguments into the inner command since it is what is passed to the virtual
     // CommandInvocation::explain() method.
-    const BSONObj explainedObj = makeExplainedObj(cmdObj, dbName);
+    const BSONObj explainedObj = makeExplainedObj(request.body, dbName);
 
     // Extract 'comment' field from the 'explainedObj' only if there is no top-level comment.
     auto commentField = explainedObj["comment"];