tdengine-mapper-go/scan.go

package tdmap

import (
	"fmt"
	"reflect"
)

func scan(data interface{}) (*StructMate, error) {
	// 获取结构体的类型
	t, v := getReflectTypeAndValue(data)

	// 确保是结构体类型
	if t.Kind() != reflect.Struct {
		return nil, fmt.Errorf("input data is not a struct")
	}

	// 获取包路径和类型名称
	uniqueTypeName := getUniqueTypeName(t)

	// 初始化结果结构体
	sr := StructMate{
		UniqueTypeName:    uniqueTypeName,
		DBName2IndexCache: make(map[string][]int, t.NumField()),
		Field2IndexCache:  make(map[string][]int, t.NumField()),
		Filed2DBNameCache: make(map[string]string, t.NumField()),
		DBAnnotatedNames:  make([]string, 0, t.NumField()),
		TaggedFieldNames:  make([]string, 0, t.NumField()),
		SuperTableName:    "",
	}

	//timeType := reflect.TypeOf(time.Time{})

	// 遍历结构体的字段
	for i := 0; i < t.NumField(); i++ {
		field := t.Field(i)
		fieldValue := v.Field(i)

		if field.Anonymous {

			if field.Type.Kind() == reflect.Ptr {
				if fieldValue.IsNil() {
					// 如果指针是 nil，创建一个该类型的零值实例
					zeroValue := reflect.Zero(field.Type.Elem())
					fieldValue = zeroValue
				} else {
					fieldValue = fieldValue.Elem()
				}
			}

			if !fieldValue.CanInterface() {
				continue
			}

			subResult, err := scan(fieldValue.Interface())
			if err != nil {
				return nil, err
			}

			for k, v := range subResult.DBName2IndexCache {
				sr.DBName2IndexCache[k] = append(sr.DBName2IndexCache[k], i)
				sr.DBName2IndexCache[k] = append(sr.DBName2IndexCache[k], v...)
			}

			for k, v := range subResult.Field2IndexCache {
				sr.Field2IndexCache[k] = append(sr.Field2IndexCache[k], i)
				sr.Field2IndexCache[k] = append(sr.Field2IndexCache[k], v...)
			}
			for k, v := range subResult.Filed2DBNameCache {
				sr.Filed2DBNameCache[k] = v
			}

			sr.DBAnnotatedNames = append(sr.DBAnnotatedNames, subResult.DBAnnotatedNames...)
			sr.TaggedFieldNames = append(sr.TaggedFieldNames, subResult.TaggedFieldNames...)

			continue
		}

		// 检查字段是否有db注解
		columnName := field.Tag.Get("db")
		if columnName == "-" || columnName == "" {
			continue
		}

		sr.Field2IndexCache[field.Name] = append(sr.Field2IndexCache[field.Name], i)
		sr.DBName2IndexCache[columnName] = append(sr.DBName2IndexCache[columnName], i)
		sr.Filed2DBNameCache[field.Name] = columnName

		// 检查字段是否有taos注解
		if field.Tag.Get("taos") == "tag" {
			sr.TaggedFieldNames = append(sr.TaggedFieldNames, field.Name)
		} else {
			sr.DBAnnotatedNames = append(sr.DBAnnotatedNames, field.Name)
		}
	}

	sr.SuperTableName = callSuperTableName(data)
	return &sr, nil
}

// 获取包路径和类型名称
func getUniqueTypeName(t reflect.Type) string {
	pkgPath := t.PkgPath()
	typeName := t.Name()
	uniqueTypeName := fmt.Sprintf("%s.%s", pkgPath, typeName)
	return uniqueTypeName
}

func getReflectTypeAndValue(data any) (reflect.Type, reflect.Value) {
	t := reflect.TypeOf(data)
	v := reflect.ValueOf(data)

	// 处理结构体和结构体指针
	for t.Kind() == reflect.Ptr {
		t = t.Elem()
		v = v.Elem()
	}
	return t, v
}

func callSuperTableName(obj any) string {
	v := reflect.ValueOf(obj)

	if v.Kind() == reflect.Struct {
		return ""
	}

	// 检查是否可以调用 SuperTableName 方法
	superTableNameMethod := v.MethodByName("SuperTableName")
	if !superTableNameMethod.IsValid() {
		return ""
	}

	// 调用 SuperTableName 方法
	results := superTableNameMethod.Call(nil)
	if len(results) == 1 && results[0].Kind() == reflect.String {
		return results[0].String()
	}
	return ""
}