fix for byte array as decimal with negative value

xitongsys · Dec 13, 2021 · b091a22 · b091a22
1 parent 444d000
commit b091a22
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Showing 3 changed files with 16 additions and 1 deletion.
diff --git a/example/type.go b/example/type.go
@@ -129,6 +129,8 @@ func main() {
 		if err = pr.Read(&tps); err != nil {
 			log.Println("Read error", err)
 		}
+		tps[0].Decimal3 = types.DECIMAL_BYTE_ARRAY_ToString([]byte(tps[0].Decimal3), 10, 2)
+		tps[0].Decimal4 = types.DECIMAL_BYTE_ARRAY_ToString([]byte(tps[0].Decimal4), 20, 2)
 		log.Println(tps)
 	}
 	pr.ReadStop()

diff --git a/types/converter.go b/types/converter.go
@@ -122,6 +122,14 @@ func DECIMAL_INT_ToString(dec int64, precision int, scale int) string {
 }
 
 func DECIMAL_BYTE_ARRAY_ToString(dec []byte, precision int, scale int) string {
+	sign := ""
+	if dec[0] > 0x7f {
+		sign = "-"
+		for i := range dec {
+			dec[i] = dec[i] ^ 0xff
+		}
+		dec[len(dec)-1] += 1
+	}
 	a := new(big.Int)
 	a.SetBytes(dec)
 	sa := a.Text(10)
@@ -130,5 +138,5 @@ func DECIMAL_BYTE_ARRAY_ToString(dec []byte, precision int, scale int) string {
 		ln := len(sa)
 		sa = sa[:ln-scale] + "." + sa[ln-scale:]
 	}
-	return sa
+	return sign + sa
 }
diff --git a/types/converter_test.go b/types/converter_test.go
@@ -37,4 +37,9 @@ func TestDECIMAL(t *testing.T) {
 		t.Error("DECIMAL_BYTE_ARRAY_ToString error: ", a3, sa3)
 	}
 
+	a4, _ := StrToParquetType("-123.456", parquet.TypePtr(parquet.Type_BYTE_ARRAY), parquet.ConvertedTypePtr(parquet.ConvertedType_DECIMAL), 9, 3)
+	sa4 := DECIMAL_BYTE_ARRAY_ToString([]byte(a4.(string)), 9, 3)
+	if sa4 != "-123.456" {
+		t.Error("DECIMAL_BYTE_ARRAY_ToString error: ", a4, sa4)
+	}
 }