feat: implement use the '-' mark to ignore writing values for field

examples/README.md

@@ -19,6 +19,7 @@ docker run --rm -p 4000-4003:4000-4003 \
 - [opentelemetry](opentelemetry/README.md)
 - [hints](hints/README.md)
 - [jsondata](jsondata/README.md)
+- [skipfields](skipfields/README.md)
 
 ## Query
 

examples/skipfields/README.md

@@ -0,0 +1,45 @@
+# Insert data into GreptimeDB
+
+When fields are marked with `greptime:"-"`, writing to these fields will be skipped.
+
+```go
+type Monitor struct {
+  ID          int64     `greptime:"tag;column:id;type:int64"`
+  Host        string    `greptime:"tag;column:host;type:string"`
+  Memory      uint64    `greptime:"-"`
+  Cpu         float64   `greptime:"field;column:cpu;type:float64"`
+  Temperature int64     `greptime:"-"`
+  Running     bool      `greptime:"field;column:running;type:boolean"`
+  Ts          time.Time `greptime:"timestamp;column:ts;type:timestamp;precision:millisecond"`
+}
+```
+
+## Insert
+
+```go
+go run main.go
+```
+
+Output:
+
+```log
+2024/12/10 09:30:40 affected rows: 1
+2024/12/10 09:30:40 affected rows: 1
+```
+
+## Query
+
+Your can using [MySQL Client](https://docs.greptime.com/user-guide/protocols/mysql) to query the data from GreptimeDB.
+
+```shell
+$ mysql -h 127.0.0.1 -P 4002
+
+mysql> select *from monitors_with_skip_fields;
++------+-----------+------+---------+----------------------------+
+| id   | host      | cpu  | running | ts                         |
++------+-----------+------+---------+----------------------------+
+|    0 | 127.0.0.1 |  1.3 |       0 | 2024-12-10 09:30:40.709000 |
+|    1 | 127.0.0.2 |  3.2 |       1 | 2024-12-10 09:30:40.709000 |
++------+-----------+------+---------+----------------------------+
+2 rows in set (0.03 sec)
+```

examples/skipfields/main.go

@@ -0,0 +1,131 @@
+// Copyright 2024 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"log"
+	"time"
+
+	greptime "github.com/GreptimeTeam/greptimedb-ingester-go"
+)
+
+const (
+	// The GreptimeDB address.
+	host = "127.0.0.1"
+
+	// The database name.
+	database = "public"
+)
+
+type Monitor struct {
+	ID          int64     `greptime:"tag;column:id;type:int64"`
+	Host        string    `greptime:"tag;column:host;type:string"`
+	Memory      uint64    `greptime:"-"`
+	Cpu         float64   `greptime:"field;column:cpu;type:float64"`
+	Temperature int64     `greptime:"-"`
+	Running     bool      `greptime:"field;column:running;type:boolean"`
+	Ts          time.Time `greptime:"timestamp;column:ts;type:timestamp;precision:millisecond"`
+}
+
+type client struct {
+	client *greptime.Client
+}
+
+func newClient() (*client, error) {
+	cfg := greptime.NewConfig(host).WithDatabase(database)
+	gtClient, err := greptime.NewClient(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &client{
+		client: gtClient,
+	}
+
+	return c, nil
+}
+
+func (Monitor) TableName() string {
+	return "monitors_with_skip_fields"
+}
+
+func initData() []Monitor {
+	return []Monitor{
+		{
+			ID:          0,
+			Host:        "127.0.0.1",
+			Memory:      1,
+			Ts:          time.Now(),
+			Cpu:         1.3,
+			Temperature: -1,
+			Running:     false,
+		},
+		{
+			ID:          1,
+			Host:        "127.0.0.2",
+			Memory:      2,
+			Ts:          time.Now(),
+			Cpu:         3.2,
+			Temperature: 1,
+			Running:     true,
+		},
+	}
+}
+
+func (c *client) writeObject(data []Monitor) error {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
+	defer cancel()
+
+	resp, err := c.client.WriteObject(ctx, data)
+	if err != nil {
+		return err
+	}
+
+	log.Printf("affected rows: %d\n", resp.GetAffectedRows().GetValue())
+	return nil
+}
+
+func (c *client) streamWriteObject(data []Monitor) error {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
+	defer cancel()
+
+	if err := c.client.StreamWriteObject(ctx, data); err != nil {
+		return err
+	}
+	affected, err := c.client.CloseStream(ctx)
+	if err != nil {
+		return err
+	}
+
+	log.Printf("affected rows: %d\n", affected.GetValue())
+	return nil
+}
+
+func main() {
+	c, err := newClient()
+	if err != nil {
+		log.Fatalf("failed to new client: %v:", err)
+	}
+
+	data := initData()
+	if err = c.writeObject(data[:1]); err != nil {
+		log.Fatalf("failed to write data: %v:", err)
+	}
+
+	if err = c.streamWriteObject(data[1:]); err != nil {
+		log.Fatalf("failed to stream write data: %v:", err)
+	}
+}

schema/field.go

@@ -52,6 +52,10 @@ func newColumnSchema(columnName string, semanticType gpb.SemanticType, datatype
 func parseField(structField reflect.StructField) (*Field, error) {
 	tags := parseTag(structField)
 
+	if _, ok := tags["-"]; ok && len(tags) == 1 {
+		return nil, nil
+	}
+
 	columnName, err := util.SanitateName(structField.Name)
 	if err != nil {
 		return nil, err

schema/schema.go

@@ -52,7 +52,7 @@ func getTableName(typ reflect.Type) (string, error) {
 
 func Parse(input any) (*table.Table, error) {
 	if input == nil {
-		return nil, fmt.Errorf("unsupported empty data. %#v", input)
+		return nil, fmt.Errorf("unsupported empty data: %#v", input)
 	}
 
 	schema_, err := parseSchema(input)
@@ -114,7 +114,9 @@ func parseSchema(input any) (*Schema, error) {
 		if err != nil {
 			return nil, err
 		}
-		fields = append(fields, field.ToColumnSchema())
+		if field != nil {
+			fields = append(fields, field.ToColumnSchema())
+		}
 	}
 
 	return &Schema{tableName: tableName, fields: fields}, nil
@@ -142,15 +144,19 @@ func (s *Schema) parseValues(input any) error {
 		return fmt.Errorf("unsupported type %T of %+v", input, input)
 	}
 
-	size := len(reflect.VisibleFields(typ))
-	values := make([]*gpb.Value, 0, size)
-	for i, structField := range reflect.VisibleFields(typ) {
-		if !structField.IsExported() {
+	visibleFields := reflect.VisibleFields(typ)
+	size := make([]reflect.StructField, 0, len(visibleFields))
+	values := make([]*gpb.Value, 0, len(size))
+
+	for _, structField := range visibleFields {
+		if !structField.IsExported() || structField.Tag.Get("greptime") == "-" {
 			continue
 		}
+		size = append(size, structField)
+	}
 
+	for i, structField := range size {
 		field := s.fields[i]
-
 		value, err := parseValue(field.Datatype, val.FieldByName(structField.Name))
 		if err != nil {
 			return err