iceberg: introduce json utils

src/v/iceberg/CMakeLists.txt

@@ -29,6 +29,7 @@ v_cc_library(
   SRCS
     ${avro_hdrs}
     datatypes.cc
+    json_utils.cc
   DEPS
     v::container
 )

src/v/iceberg/json_utils.cc

@@ -0,0 +1,72 @@
+// Copyright 2024 Redpanda Data, Inc.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.md
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0
+
+#include "json/document.h"
+
+#include <fmt/format.h>
+
+#include <stdexcept>
+
+namespace iceberg {
+
+std::optional<std::reference_wrapper<const json::Value>>
+parse_optional(const json::Value& v, const char* member_name) {
+    if (!v.IsObject()) {
+        throw std::invalid_argument(
+          fmt::format("Expected JSON object to parse field '{}'", member_name));
+    }
+    auto iter = v.FindMember(member_name);
+    if (iter == v.MemberEnd()) {
+        return std::nullopt;
+    }
+    return iter->value;
+}
+
+const json::Value&
+parse_required(const json::Value& v, const char* member_name) {
+    if (!v.IsObject()) {
+        throw std::invalid_argument(
+          fmt::format("Expected JSON object to parse field '{}'", member_name));
+    }
+    auto iter = v.FindMember(member_name);
+    if (iter == v.MemberEnd()) {
+        throw std::invalid_argument(
+          fmt::format("No member named '{}'", member_name));
+    }
+    return iter->value;
+}
+
+ss::sstring parse_required_str(const json::Value& v, const char* member_name) {
+    const auto& str_json = parse_required(v, member_name);
+    if (!str_json.IsString()) {
+        throw std::invalid_argument(
+          fmt::format("Expected string for field '{}'", member_name));
+    }
+    return str_json.GetString();
+}
+
+int32_t parse_required_i32(const json::Value& v, const char* member_name) {
+    const auto& int_json = parse_required(v, member_name);
+    if (!int_json.IsInt()) {
+        throw std::invalid_argument(
+          fmt::format("Expected integer for field '{}'", member_name));
+    }
+    return int_json.GetInt();
+}
+
+bool parse_required_bool(const json::Value& v, const char* member_name) {
+    const auto& bool_json = parse_required(v, member_name);
+    if (!bool_json.IsBool()) {
+        throw std::invalid_argument(
+          fmt::format("Expected bool for field '{}'", member_name));
+    }
+    return bool_json.GetBool();
+}
+
+} // namespace iceberg

src/v/iceberg/json_utils.h

@@ -0,0 +1,27 @@
+// Copyright 2024 Redpanda Data, Inc.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.md
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0
+#pragma once
+
+#include "json/document.h"
+
+namespace iceberg {
+
+std::optional<std::reference_wrapper<const json::Value>>
+parse_optional(const json::Value& v, const char* member_name);
+
+const json::Value&
+parse_required(const json::Value& v, const char* member_name);
+
+ss::sstring parse_required_str(const json::Value& v, const char* member_name);
+
+int32_t parse_required_i32(const json::Value& v, const char* member_name);
+
+bool parse_required_bool(const json::Value& v, const char* member_name);
+
+} // namespace iceberg