From b2de82670df455b8c2d14993b6631054772cced6 Mon Sep 17 00:00:00 2001
From: Cheng Xuntao <7731943+xtcyclist@users.noreply.github.com>
Date: Thu, 29 Dec 2022 16:34:43 +0800
Subject: [PATCH] Revert "Remove all UNKNOWN_PROP as a type of null. (#4907)"
 (#5149)

This reverts commit aa624162abaf92eeb6c2e5a8c35d31acc9366846.

Co-authored-by: Sophie <84560950+Sophie-Xie@users.noreply.github.com>
---
 src/common/expression/AttributeExpression.cpp          | 2 +-
 src/common/expression/test/AttributeExpressionTest.cpp | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/common/expression/AttributeExpression.cpp b/src/common/expression/AttributeExpression.cpp
index 20438134d57..7ddac8585b3 100644
--- a/src/common/expression/AttributeExpression.cpp
+++ b/src/common/expression/AttributeExpression.cpp
@@ -33,7 +33,7 @@ const Value &AttributeExpression::eval(ExpressionContext &ctx) {
           return iter->second;
         }
       }
-      return Value::kNullValue;
+      return Value::kNullUnknownProp;
     }
     case Value::Type::EDGE: {
       DCHECK(!rvalue.getStr().empty());
diff --git a/src/common/expression/test/AttributeExpressionTest.cpp b/src/common/expression/test/AttributeExpressionTest.cpp
index 1258e953bfa..5b3dbbe5870 100644
--- a/src/common/expression/test/AttributeExpressionTest.cpp
+++ b/src/common/expression/test/AttributeExpressionTest.cpp
@@ -134,7 +134,7 @@ TEST_F(AttributeExpressionTest, DateTimeAttribute) {
     auto *right = LabelExpression::make(&pool, "not exist attribute");
     auto expr = AttributeExpression::make(&pool, left, right);
     auto value = Expression::eval(expr, gExpCtxt);
-    ASSERT_EQ(Value::kNullValue, value);
+    ASSERT_EQ(Value::kNullUnknownProp, value);
   }
   {
     auto *left = ConstantExpression::make(&pool, Value(dt));
@@ -148,7 +148,7 @@ TEST_F(AttributeExpressionTest, DateTimeAttribute) {
     auto *right = LabelExpression::make(&pool, "not exist attribute");
     auto expr = AttributeExpression::make(&pool, left, right);
     auto value = Expression::eval(expr, gExpCtxt);
-    ASSERT_EQ(Value::kNullValue, value);
+    ASSERT_EQ(Value::kNullUnknownProp, value);
   }
   {
     auto *left = ConstantExpression::make(&pool, Value(d));
@@ -162,7 +162,7 @@ TEST_F(AttributeExpressionTest, DateTimeAttribute) {
     auto *right = LabelExpression::make(&pool, "not exist attribute");
     auto expr = AttributeExpression::make(&pool, left, right);
     auto value = Expression::eval(expr, gExpCtxt);
-    ASSERT_EQ(Value::kNullValue, value);
+    ASSERT_EQ(Value::kNullUnknownProp, value);
   }
   {
     auto *left = ConstantExpression::make(&pool, Value(t));