Introduce JSON_EXTRACT function

close: #3513 Note, we don't support the path argument in this phase
vesoft-inc · Oct 19, 2022 · 3c9b0b2 · 3c9b0b2
1 parent 95e0f43
commit 3c9b0b2
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diff --git a/src/common/datatypes/Map.h b/src/common/datatypes/Map.h
@@ -8,6 +8,8 @@
 
 #include <unordered_map>
 
+#include <folly/json.h>
+
 #include "common/datatypes/Value.h"
 
 namespace nebula {
@@ -22,6 +24,22 @@ struct Map {
     kvs = std::move(values);
   }
 
+  // constructor to convert from json string
+  explicit Map(const std::string& json) {
+    auto obj = folly::parseJson(json);
+    for (auto& kv : obj.items()) {
+      kvs.emplace(kv.first.getString(), Value(kv.second));
+    }
+  }
+
+  // constructor to convert from Value::Type::STRING in JSON format
+  explicit Map(const Value& value) {
+    auto obj = folly::parseJson(value.getStr());
+    for (auto& kv : obj.items()) {
+      kvs.emplace(kv.first.getString(), Value(kv.second));
+    }
+  }
+
   Map& operator=(const Map& rhs) {
     if (this == &rhs) {
       return *this;

diff --git a/src/common/function/FunctionManager.cpp b/src/common/function/FunctionManager.cpp
@@ -421,6 +421,7 @@ std::unordered_map<std::string, std::vector<TypeSignature>> FunctionManager::typ
       TypeSignature({Value::Type::MAP}, Value::Type::DURATION)}},
     {"extract", {TypeSignature({Value::Type::STRING, Value::Type::STRING}, Value::Type::LIST)}},
     {"_nodeid", {TypeSignature({Value::Type::PATH, Value::Type::INT}, Value::Type::INT)}},
+    {"json_extract", {TypeSignature({Value::Type::STRING}, Value::Type::MAP)}},
 };
 
 // static
@@ -2766,6 +2767,20 @@ FunctionManager::FunctionManager() {
       }
     };
   }
+  {
+    auto &attr = functions_["json_extract"];
+    // note, we don't support second argument(path) like MySQL JSON_EXTRACT for now
+    attr.minArity_ = 1;
+    attr.maxArity_ = 1;
+    attr.isAlwaysPure_ = true;
+    attr.body_ = [](const auto &args) -> Value {
+      if (!args[0].get().isStr()) {
+        return Value::kNullBadType;
+      }
+      auto json = args[0].get().getStr();
+      return Map(json);
+    };
+  }
 }  // NOLINT
 
 // static

diff --git a/src/common/function/test/FunctionManagerTest.cpp b/src/common/function/test/FunctionManagerTest.cpp
@@ -1962,6 +1962,22 @@ TEST_F(FunctionManagerTest, PurityTest) {
   ASSERT_TRUE(result.ok() && result.value() == true);
 }
 
+TEST_F(FunctionManagerTest, JsonExtract) {
+  {
+    std::vector<Value> args = {Value(R"({"a": 1, "b": 2})")};
+    TEST_FUNCTION(jsonExtract, args, {Map({{"a", 1}, {"b", 2}})});
+  }
+  // empty string
+  {
+    std::vector<Value> args = {Value("")};
+    TEST_FUNCTION(jsonExtract, args, Value::kNullBadData);
+  }
+  // invalid json string
+  {
+    std::vector<Value> args = {Value(R"({a: 1, "b": 2})")};
+    TEST_FUNCTION(jsonExtract, args, Value::kNullBadData);
+  }
+
 }  // namespace nebula
 
 int main(int argc, char **argv) {