Merge pull request #81 from mailru/develop

Nullable fields, go 1.12

.travis.yml

@@ -6,6 +6,7 @@ go:
   - '1.9'
   - '1.10'
   - '1.11'
+  - '1.12'
 
 services:
   - docker

README.md

@@ -142,7 +142,7 @@ func main() {
 	}
 
 	rows, err := connect.Query(`
-		SELECT 
+		SELECT
 			country_code,
 			os_id,
 			browser_id,

dataparser.go

@@ -43,6 +43,23 @@ type dateTimeParser struct {
 	location *time.Location
 }
 
+type nullableParser struct {
+	DataParser
+}
+
+func (p *nullableParser) Parse(s io.RuneScanner) (driver.Value, error) {
+	// Clickhouse returns `\N` string for `null` in tsv format.
+	// For checking this value we need to check first two runes in `io.RuneScanner`, but we can't reset `io.RuneScanner` after it.
+	// Copy io.RuneScanner to `bytes.Buffer` and use it twice (1st for casting to string and checking to null, 2nd for passing to original parser)
+	d := readRaw(s)
+
+	if bytes.Equal(d.Bytes(), []byte(`\N`)) {
+		return nil, nil
+	}
+
+	return p.DataParser.Parse(d)
+}
+
 func readNumber(s io.RuneScanner) (string, error) {
 	var builder bytes.Buffer
 
@@ -384,7 +401,14 @@ func newDataParser(t *TypeDesc, unquote bool, opt *DataParserOptions) (DataParse
 	case "Nothing":
 		return &nothingParser{}, nil
 	case "Nullable":
-		return nil, fmt.Errorf("Nullable types are not supported")
+		if len(t.Args) == 0 {
+			return nil, fmt.Errorf("Nullable should pass original type")
+		}
+		p, err := newDataParser(t.Args[0], unquote, opt)
+		if err != nil {
+			return nil, err
+		}
+		return &nullableParser{p}, nil
 	case "Date":
 		loc := time.UTC
 		if opt != nil && opt.Location != nil {

dataparser_test.go

@@ -32,10 +32,16 @@ func TestParseData(t *testing.T) {
 
 	testCases := []*testCase{
 		{
-			name:          "nullable not supported",
-			inputtype:     "Nullable(String)",
-			inputdata:     "NULL",
-			failNewParser: true,
+			name:      "nullable string",
+			inputtype: "Nullable(String)",
+			inputdata: `\N`,
+			output:    nil,
+		},
+		{
+			name:      "nullable int not null",
+			inputtype: "Nullable(UInt64)",
+			inputdata: "655",
+			output:    uint64(655),
 		},
 		{
 			name:      "string",

tokenizer.go

@@ -60,6 +60,22 @@ func readEscaped(s io.RuneScanner) (rune, error) {
 	}
 }
 
+func readRaw(s io.RuneScanner) *bytes.Buffer {
+	var data bytes.Buffer
+
+	for {
+		r := read(s)
+
+		if r == eof {
+			break
+		}
+
+		data.WriteRune(r)
+	}
+
+	return &data
+}
+
 func readQuoted(s io.RuneScanner) (*token, error) {
 	var data bytes.Buffer