[NSE-583] impl get_json_object in wscg (#619)

* impl get_json_object in wscg Signed-off-by: Yuan Zhou <[email protected]> * fix header Signed-off-by: Yuan Zhou <[email protected]> * fix Signed-off-by: Yuan Zhou <[email protected]> * fix Signed-off-by: Yuan Zhou <[email protected]>
oap-project · Dec 13, 2021 · 7ad8194 · 7ad8194
1 parent 604d17b
commit 7ad8194
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diff --git a/native-sql-engine/cpp/src/codegen/arrow_compute/ext/expression_codegen_visitor.cc b/native-sql-engine/cpp/src/codegen/arrow_compute/ext/expression_codegen_visitor.cc
@@ -246,6 +246,21 @@ arrow::Status ExpressionCodegenVisitor::Visit(const gandiva::FunctionNode& node)
                << ".rfind(" << child_visitor_list[1]->GetResult()
                << ") != std::string::npos;";
     prepare_str_ += prepare_ss.str();
+  } else if (func_name.compare("get_json_object") == 0) {
+    for (int i = 0; i < 2; i++) {
+      prepare_str_ += child_visitor_list[i]->GetPrepare();
+    }
+    codes_str_ = "get_json_object_" + std::to_string(cur_func_id);
+    check_str_ = GetValidityName(codes_str_);
+    real_codes_str_ = codes_str_;
+    real_validity_str_ = check_str_;
+    std::stringstream prepare_ss;
+    prepare_ss << "bool " << check_str_ << " = true;" << std::endl;
+    prepare_ss << "std::string " << codes_str_ << " = get_json_object("
+               << child_visitor_list[0]->GetResult() << ", "
+               << child_visitor_list[1]->GetResult() << ");\n";
+    prepare_str_ += prepare_ss.str();
+    header_list_.push_back(R"(#include "precompile/gandiva.h")");
   } else if (func_name.compare("substr") == 0) {
     ss << child_visitor_list[0]->GetResult() << ".substr("
        << "((" << child_visitor_list[1]->GetResult() << " - 1) < 0 ? 0 : ("

diff --git a/native-sql-engine/cpp/src/precompile/gandiva.h b/native-sql-engine/cpp/src/precompile/gandiva.h
@@ -16,6 +16,9 @@
  */
 #pragma once
 
+#include <arrow/array.h>
+#include <arrow/json/api.h>
+#include <arrow/json/parser.h>
 #include <arrow/util/decimal.h>
 #include <math.h>
 
@@ -226,3 +229,37 @@ arrow::Decimal128 round(arrow::Decimal128 in, int32_t original_precision,
   }
   return arrow::Decimal128(out);
 }
+
+std::string get_json_object(const std::string& json_str, const std::string& json_path) {
+  std::unique_ptr<arrow::json::BlockParser> parser;
+  (arrow::json::BlockParser::Make(arrow::json::ParseOptions::Defaults(), &parser));
+  (parser->Parse(std::make_shared<arrow::Buffer>(json_str)));
+  std::shared_ptr<arrow::Array> parsed;
+  (parser->Finish(&parsed));
+  auto struct_parsed = std::dynamic_pointer_cast<arrow::StructArray>(parsed);
+  // json_path example: $.col_14, will extract col_14 here
+  if (json_path.length() < 3) {
+    return nullptr;
+  }
+  auto col_name = json_path.substr(2);
+  // illegal json string.
+  if (struct_parsed == nullptr) {
+    return nullptr;
+  }
+  auto dict_parsed = std::dynamic_pointer_cast<arrow::DictionaryArray>(
+      struct_parsed->GetFieldByName(col_name));
+  // no data contained for given field.
+  if (dict_parsed == nullptr) {
+    return nullptr;
+  }
+
+  auto dict_array = dict_parsed->dictionary();
+  // needs to see whether there is a case that has more than one indices.
+  auto res_index = dict_parsed->GetValueIndex(0);
+  // TODO(): check null results
+  auto utf8_array = std::dynamic_pointer_cast<arrow::BinaryArray>(dict_array);
+
+  auto res = utf8_array->GetString(res_index);
+
+  return res;
+}
diff --git a/native-sql-engine/cpp/src/tests/arrow_compute_test_precompile.cc b/native-sql-engine/cpp/src/tests/arrow_compute_test_precompile.cc
@@ -111,5 +111,10 @@ TEST(TestArrowCompute, ArithmeticComparisonTest) {
   ASSERT_EQ(res, true);
 }
 
+TEST(TestArrowCompute, JsonTest) {
+  std::string data = get_json_object(R"({"hello": "3.5"})", "$.hello");
+  EXPECT_EQ(data, "3.5");
+}
+
 }  // namespace codegen
 }  // namespace sparkcolumnarplugin